Ali-Reza Adl-Tabatabai

A method and apparatus for optimizing quiescence in a transactional memory system is herein described. Non-ordering transactions, such as read-only transactions, transactions that do not access non-transactional data, and write-buffering hardware transactions, are identified. Quiescence in weak atomicity software transactional memory (STM) systems is optimized through selective application of quiescence. As a result, transactions may be decoupled from dependency on quiescing/waiting on previous… Show more

A method and apparatus for optimizing quiescence in a transactional memory system is herein described. Non-ordering transactions, such as read-only transactions, transactions that do not access non-transactional data, and write-buffering hardware transactions, are identified. Quiescence in weak atomicity software transactional memory (STM) systems is optimized through selective application of quiescence. As a result, transactions may be decoupled from dependency on quiescing/waiting on previous non-ordering transaction to increase parallelization and reduce inefficiency based on serialization of transactions. Show less

A system for optimizing cache coherence message traffic volume is disclosed. The system includes a plurality of caches in a multi-level memory hierarchy and a plurality of agents. Each agent is associated with a cache. The system includes one or more monitoring engines. Each agent in the plurality of agents is associated with a monitoring engine. The agents can execute a processor level software instruction causing a memory region to be private to the agent. Each of the agents is configured to… Show more

A system for optimizing cache coherence message traffic volume is disclosed. The system includes a plurality of caches in a multi-level memory hierarchy and a plurality of agents. Each agent is associated with a cache. The system includes one or more monitoring engines. Each agent in the plurality of agents is associated with a monitoring engine. The agents can execute a processor level software instruction causing a memory region to be private to the agent. Each of the agents is configured to execute a memory access for data on an associated cache and to send a request for data up the hierarchy on a cache miss. The monitoring engine is configured to intercept request for data from an agent and to prevent snooping for the cache line in peer caches when the cache line associated with a memory region represented as private to the agent. Show less

A memory race recorder (MRR) is provided. The MRR includes a multi-core processor having a relaxed memory consistency model, an extension to the multi-core processor, the extension to store chunks, the chunk having a chunk size (CS) and an instruction count (IC), and a plurality of cores to execute instructions. The plurality of cores executes load/store instructions to/from a store buffer (STB) and a simulated memory to store the value when the value is not in the STB. The oldest value in the… Show more

A memory race recorder (MRR) is provided. The MRR includes a multi-core processor having a relaxed memory consistency model, an extension to the multi-core processor, the extension to store chunks, the chunk having a chunk size (CS) and an instruction count (IC), and a plurality of cores to execute instructions. The plurality of cores executes load/store instructions to/from a store buffer (STB) and a simulated memory to store the value when the value is not in the STB. The oldest value in the STB is transferred to the simulated memory when the IC is equal to zero and the CS is greater than zero. The MRR logs a trace entry comprising the CS, the IC, and a global timestamp, the global timestamp proving a total order across all logged chunks.
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Disclosed here are methods, systems, paradigms and structures for incrementally compiling scripts at runtime to generate executable code. The incremental compilation generates executable code corresponding to basic blocks of a script in various phases and at various scopes. In a first phase, an executable code for a basic block of the script is generated for a set of types of variables of the basic block. The generated executable block is stored and executed for subsequent requests. In a second… Show more

Disclosed here are methods, systems, paradigms and structures for incrementally compiling scripts at runtime to generate executable code. The incremental compilation generates executable code corresponding to basic blocks of a script in various phases and at various scopes. In a first phase, an executable code for a basic block of the script is generated for a set of types of variables of the basic block. The generated executable block is stored and executed for subsequent requests. In a second phase, a set of executable blocks whose profiling information, such as frequency of (a) execution, (b) transition between two executable blocks, or (c) execution of a particular path, satisfies an optimization criterion is identified. The identified set of executable blocks are combined to generate an executable control region, which is more optimal than the executable blocks generated in the first phase. The executable control region is executed for subsequent requests. Show less

Disclosed here are methods, systems, paradigms and structures for optimizing generation of intermediate representation (IR) for a script code by eliminating redundant object reference count operations from the IR. An IR of the script includes (a) a set of first code that increments a reference count of an object when a programming construct refers to the object, and (b) an associated set of second code which decrements the reference count of the object when a reference to the object is removed.… Show more

Disclosed here are methods, systems, paradigms and structures for optimizing generation of intermediate representation (IR) for a script code by eliminating redundant object reference count operations from the IR. An IR of the script includes (a) a set of first code that increments a reference count of an object when a programming construct refers to the object, and (b) an associated set of second code which decrements the reference count of the object when a reference to the object is removed. The IR is analyzed to identify a subset of the set of second code which, upon execution, does not decrement the reference count of the object to a zero value. The subset of second code and the first code corresponding to the subset is removed from the IR to generate an optimized IR. The optimized IR is further converted to an executable code. Show less

A method and apparatus for hybrid validation for a Software Transaction Memory (STM) is herein described. During execution of a transaction, when acquiring ownership of meta-data associated with a data element, the meta-data is updated with an ownership reference to a transaction to enable efficient subsequent ownership tests. However, during validation, for some conditions, meta-data is updated from the ownership reference to a write entry reference to enable efficient validation.

Disclosed here are methods, systems, paradigms and structures for optimizing intermediate representation (IR) of a script code for atomic execution. Atomic execution of the script is achieved by generating portions of the IR as an atomic transaction. In an atomic transaction, a series of operations either all execute, or none executes. The IR includes checkpoints that evaluate to one of two possible values. The checkpoint evaluates to a first value when there is no error during execution, and… Show more

Disclosed here are methods, systems, paradigms and structures for optimizing intermediate representation (IR) of a script code for atomic execution. Atomic execution of the script is achieved by generating portions of the IR as an atomic transaction. In an atomic transaction, a series of operations either all execute, or none executes. The IR includes checkpoints that evaluate to one of two possible values. The checkpoint evaluates to a first value when there is no error during execution, and evaluates to a second value when an error occurs. The IR is optimized for atomic execution by regenerating a portion of the IR including the checkpoint and code associated with the checkpoint as a transaction. When an error occurs during the execution of the transaction, the transaction is aborted and a state of execution of the script code is reverted to a state prior to the beginning of the transaction. Show less

Disclosed here are methods, systems, paradigms and structures for optimizing intermediate representation (IR) of a script code for fast path execution. A fast path is typically a path that handles most commonly occurring tasks more efficiently than less commonly occurring ones which are handled by slow paths. The less commonly occurring tasks may include uncommon cases, error handling, and other anomalies. The IR includes checkpoints which evaluate to two possible values resulting in either a… Show more

Disclosed here are methods, systems, paradigms and structures for optimizing intermediate representation (IR) of a script code for fast path execution. A fast path is typically a path that handles most commonly occurring tasks more efficiently than less commonly occurring ones which are handled by slow paths. The less commonly occurring tasks may include uncommon cases, error handling, and other anomalies. The IR includes checkpoints which evaluate to two possible values resulting in either a fast path or slow path execution. The IR is optimized for fast path execution by regenerating a checkpoint as a labeled checkpoint. The code in the portion of the IR following the checkpoint is optimized assuming the checkpoint evaluates to a value resulting in fast path. The code for handling situations where the checkpoint evaluates to a value resulting in slow path is transferred to a portion of the IR identified by the label. Show less

A method and apparatus for accelerating a Software Transactional Memory (STM) system is herein described. A data object and metadata for the data object may each be associated with a filter, such as a hardware monitor or ephemerally held filter information. The filter is in a first, default state when no access, such as a read, from the data object has occurred during a pendancy of a transaction. Upon encountering a first access to the metadata, such as a first read, access barrier operations… Show more

A method and apparatus for accelerating a Software Transactional Memory (STM) system is herein described. A data object and metadata for the data object may each be associated with a filter, such as a hardware monitor or ephemerally held filter information. The filter is in a first, default state when no access, such as a read, from the data object has occurred during a pendancy of a transaction. Upon encountering a first access to the metadata, such as a first read, access barrier operations, such as logging of the metadata; setting a read monitor; or updating ephemeral filter information with an ephemeral/buffered store operation, are performed. Upon a subsequent/redundant access to the metadata, such as a second read, access barrier operations are elided to accelerate the subsequent access based on the filter being set to the second state to indicate a previous access occurred. Additionally, mapping of data objects to ephemeral information may be provided by software, such as through a pointer to the ephemeral information associated with the data object; an offset from a base address of the data object to the ephemeral information included associated with the data object; an index into a segment containing the ephemeral information associated with the data object; mapping the data object to the ephemeral information utilizing address arithmetic; and a hash that maps the data object to ephemeral information.
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A method and apparatus for optimizing weak atomicity overhead is herein described. A state table is maintained either during static or dynamic compilation of code to track data non-transactionally accessed. Within execution of a transaction, such as at transactional memory accesses or within a commit function, it is determined if data associated with memory access within the transaction is to be conflictingly accessed outside the transaction from the state table. If the data is not accessed… Show more

A method and apparatus for optimizing weak atomicity overhead is herein described. A state table is maintained either during static or dynamic compilation of code to track data non-transactionally accessed. Within execution of a transaction, such as at transactional memory accesses or within a commit function, it is determined if data associated with memory access within the transaction is to be conflictingly accessed outside the transaction from the state table. If the data is not accessed outside the transaction, then the transaction potentially commits without weak atomicity safety mechanisms, such as privatization. Furthermore, even if data is accessed outside the transaction, optimized safety mechanisms may be performed to ensure isolation between the potentially conflicting accesses, while eliding the mechanisms for data not accessed outside the transaction.
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Techniques provided herein facilitate just-in-time compilation of source code, such as a script, during execution. According to some embodiments, a tracelet is limited to a single basic block of code. The data types of variable values provided by one or more variables used in the single basic block of code are known by generalized categories, rather than only being known by specific data types. Accordingly, guard code associated with each tracelet, which ensures that variable values received by… Show more

Techniques provided herein facilitate just-in-time compilation of source code, such as a script, during execution. According to some embodiments, a tracelet is limited to a single basic block of code. The data types of variable values provided by one or more variables used in the single basic block of code are known by generalized categories, rather than only being known by specific data types. Accordingly, guard code associated with each tracelet, which ensures that variable values received by the tracelet though the variables are of the data types expected by the tracelet's associated code body, can use generalized data types. The tracelet can contain code body that can handle input values that meet those generalized data types. A generalized data type can be defined according to one or more common characteristics shared by two or more specific data types. Show less

Methods and systems to identify and reproduce concurrency bugs in multi-threaded programs are disclosed. An example method disclosed herein includes defining a data type. The data type includes a first predicate associated with a first thread of a multi-threaded program that is associated with a first condition, a second predicate that is associated with a second thread of the multi-threaded program, the second predicate being associated with a second condition, and an expression that defines a… Show more

Methods and systems to identify and reproduce concurrency bugs in multi-threaded programs are disclosed. An example method disclosed herein includes defining a data type. The data type includes a first predicate associated with a first thread of a multi-threaded program that is associated with a first condition, a second predicate that is associated with a second thread of the multi-threaded program, the second predicate being associated with a second condition, and an expression that defines a relationship between the first predicate and the second predicate. The relationship, when satisfied, causes the concurrency bug to be detected. A concurrency bug detector conforming to the data type is used to detect the concurrency bug in the multi-threaded program. Show less

Monitoring performance of one or more architecturally significant processor caches coupled to a processor. The methods include executing an application on one or more processors coupled to one or more architecturally significant processor caches, where the application utilizes the architecturally significant portions of the architecturally significant processor caches. The methods further include at least one of generating metrics related to performance of the architecturally significant… Show more

Monitoring performance of one or more architecturally significant processor caches coupled to a processor. The methods include executing an application on one or more processors coupled to one or more architecturally significant processor caches, where the application utilizes the architecturally significant portions of the architecturally significant processor caches. The methods further include at least one of generating metrics related to performance of the architecturally significant processor caches; implementing one or more debug exceptions related to performance of the architecturally significant processor caches; or implementing one or more transactional breakpoints related to performance of the architecturally significant processor caches as a result of utilizing the architecturally significant portions of the architecturally significant processor caches.
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Disclosed here are methods, systems, paradigms and structures for incrementally compiling scripts at runtime to generate executable code. In a first phase, an executable block for a basic block of the script is generated for a set of types of variables of the basic block. In a second phase, a set of executable blocks whose profiling information, such as frequency of (a) execution, (b) transition between executable blocks, or (c) execution of a path, satisfies an optimization criterion is… Show more

Disclosed here are methods, systems, paradigms and structures for incrementally compiling scripts at runtime to generate executable code. In a first phase, an executable block for a basic block of the script is generated for a set of types of variables of the basic block. In a second phase, a set of executable blocks whose profiling information, such as frequency of (a) execution, (b) transition between executable blocks, or (c) execution of a path, satisfies an optimization criterion is identified, and an executable control region is generated. In a third phase, profiling information from a number of systems in a distributed environment is aggregated, and an executable control region corresponding to the aggregated profile is generated. The executable code generated in each of the phases is more optimal than the code generated in a previous phase, and is used for execution until replaced by the code of a subsequent phase. Show less

Methods, systems, and mediums are described for scheduling data parallel tasks onto multiple thread execution units of processing system. Embodiments of a lock-free queue structure and methods of operation are described to implement a method for scheduling fine-grained data-parallel tasks for execution in a computing system. The work of one of a plurality of worker threads is wait-free with respect to the other worker threads. Each node of the queue holds a reference to a task that may be… Show more

Methods, systems, and mediums are described for scheduling data parallel tasks onto multiple thread execution units of processing system. Embodiments of a lock-free queue structure and methods of operation are described to implement a method for scheduling fine-grained data-parallel tasks for execution in a computing system. The work of one of a plurality of worker threads is wait-free with respect to the other worker threads. Each node of the queue holds a reference to a task that may be concurrently performed by multiple thread execution units, but each on a different subset of data. Various embodiments relate to software-based scheduling of data-parallel tasks on a multi-threaded computing platform that does not perform such scheduling in hardware. Other embodiments are also described and claimed.
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Methods for mapping a function pointer to the device code are presented. In one embodiment, a method includes identifying a function which is executable by processing devices. The method includes generating codes including a first code corresponds to a first processing device and a second code corresponds to a second processing device. The second processing device is architecturally different from the first processing device. The method further includes storing the second code in a byte string… Show more

Methods for mapping a function pointer to the device code are presented. In one embodiment, a method includes identifying a function which is executable by processing devices. The method includes generating codes including a first code corresponds to a first processing device and a second code corresponds to a second processing device. The second processing device is architecturally different from the first processing device. The method further includes storing the second code in a byte string such that the second code is retrievable if the function will be executed by the second processing device. Show less

Private or shared read-only memory regions. One embodiment may be practiced in a computing environment including a plurality of agents. A method includes acts for declaring one or more memory regions private to a particular agent or shared read only amongst agents by having software utilize processor level instructions to specify to hardware the private or shared read only memory address regions. The method includes an agent executing a processor level instruction to specify one or more memory… Show more

Private or shared read-only memory regions. One embodiment may be practiced in a computing environment including a plurality of agents. A method includes acts for declaring one or more memory regions private to a particular agent or shared read only amongst agents by having software utilize processor level instructions to specify to hardware the private or shared read only memory address regions. The method includes an agent executing a processor level instruction to specify one or more memory regions as private to the agent or shared read-only amongst a plurality of agents. As a result of an agent executing a processor level instruction to specify one or more memory regions as private to the agent or shared read-only amongst a plurality of agents, a hardware component monitoring the one or more memory regions for conflicting accesses or prevents conflicting accesses on the one or more memory regions.
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A method and system to facilitate a user level application executing in a first processing unit to enqueue work or task(s) safely for a second processing unit without performing any ring transition. For example, in one embodiment of the invention, the first processing unit executes one or more user level applications, where each user level application has a task to be offloaded to a second processing unit. The first processing unit signals the second processing unit to handle the task from each… Show more

A method and system to facilitate a user level application executing in a first processing unit to enqueue work or task(s) safely for a second processing unit without performing any ring transition. For example, in one embodiment of the invention, the first processing unit executes one or more user level applications, where each user level application has a task to be offloaded to a second processing unit. The first processing unit signals the second processing unit to handle the task from each user level application without performing any ring transition in one embodiment of the invention. Show less

A method and apparatus for utilizing hardware mechanisms of a transactional memory system is herein described. Various embodiments relate to software-based filtering of operations from read and write barriers and read isolation barriers during transactional execution. Other embodiments relate to software-implemented read barrier processing to accelerate strong atomicity. Other embodiments are also described and claimed.

A method and apparatus for enabling a Software Transactional Memory (STM) with precompiled binaries is herein described. Upon encountering an access operation in a transaction, an annotation field associated with a memory location referenced by the access is checked. In response to the memory location representing a previous similar access within the transaction, the access is performed without access barriers. However, if the annotation field is in a default state representing no previous… Show more

A method and apparatus for enabling a Software Transactional Memory (STM) with precompiled binaries is herein described. Upon encountering an access operation in a transaction, an annotation field associated with a memory location referenced by the access is checked. In response to the memory location representing a previous similar access within the transaction, the access is performed without access barriers. However, if the annotation field is in a default state representing no previous access during a pendancy of the transaction, then a mode of the processor is determined. If the processor mode is in implicit mode, an access handler/barrier is asynchronously executed. Conversely, in an explicit mode, a flag is set instead of asynchronously executing the handler. In addition, during compilation convert explicit and convert implicit instructions are inserted to intelligently convert modes for precompiled and newly compiled binaries. Furthermore, new versions of newly compiled functions may be inserted to provide strong atomicity between previously and newly compiled functions.
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A method and apparatus for providing efficient strong atomicity is herein described. Optimized strong operations may be inserted at non-transactional read accesses to provide efficient strong atomicity. A global transaction value is copied at a beginning of a non-transactional function to a local transaction value; essentially creating a local timestamp of the global transaction value. At a non-transactional memory access within the function, a counter value or version value is compared to the… Show more

A method and apparatus for providing efficient strong atomicity is herein described. Optimized strong operations may be inserted at non-transactional read accesses to provide efficient strong atomicity. A global transaction value is copied at a beginning of a non-transactional function to a local transaction value; essentially creating a local timestamp of the global transaction value. At a non-transactional memory access within the function, a counter value or version value is compared to the LTV to see if a transaction has started updating memory locations, or specifically the memory location accessed. If memory locations have not been updated by a transaction, execution is accelerated by avoiding a full set of slowpath strong atomic operations to ensure validity of data accessed. In contrast, the slowpath operations may be executed to resolve contention between a transactional and non-transaction access contending for the same memory location. Show less

Methods and apparatus to provide unbounded transactional memory systems are described. In one embodiment, an operation corresponding to a software transactional memory (STM) access may be executed if a preceding hardware transactional memory (HTM) access operation fails.

A method and apparatus for accelerating lookups in an address based table is herein described. When an address and value pair is added to an address based table, the value is privately stored in the address to allow for quick and efficient local access to the value. In response to the private store, a cache line holding the value is transitioned to a private state, to ensure the value is not made globally visible. Upon eviction of the privately held cache line, the information is not… Show more

A method and apparatus for accelerating lookups in an address based table is herein described. When an address and value pair is added to an address based table, the value is privately stored in the address to allow for quick and efficient local access to the value. In response to the private store, a cache line holding the value is transitioned to a private state, to ensure the value is not made globally visible. Upon eviction of the privately held cache line, the information is not written-back to ensure locality of the value. In one embodiment, the address based table includes a transactional write buffer to hold addresses, which correspond to tentatively updated values during a transaction. Accesses to the tentative values during the transaction may be accelerated through use of annotation bits and private stores as discussed herein. Upon commit of the transaction, the values are copied to the location to make the updates globally visible. Show less

A method and apparatus for designating and handling irrevocable transactions is herein described. In response to detecting an irrevocable event, such as an I/O operation, a user-defined irrevocable designation, and a dynamic failure profile, a transaction is designated as irrevocable. In response to designating a transaction as irrevocable, Single Owner Read Locks (SORLs) are acquired for previous and subsequent reads in the irrevocably designated transaction to ensure the transaction is able… Show more

A method and apparatus for designating and handling irrevocable transactions is herein described. In response to detecting an irrevocable event, such as an I/O operation, a user-defined irrevocable designation, and a dynamic failure profile, a transaction is designated as irrevocable. In response to designating a transaction as irrevocable, Single Owner Read Locks (SORLs) are acquired for previous and subsequent reads in the irrevocably designated transaction to ensure the transaction is able to complete without modification to locations read from, while permitting remote resources to load from those locations to continue execution. Show less

A method and apparatus for dynamic optimization of strong atomicity barriers is herein described. During runtime compilation, code including non-transactional memory accesses that are to conflict with transactional memory accesses is patched to insert transactional barriers at the conflicting non-transactional memory accesses to ensure isolation and strong atomicity. However, barriers are omitted or removed from non-transactional memory accesses that do not conflict with transactional memory… Show more

A method and apparatus for dynamic optimization of strong atomicity barriers is herein described. During runtime compilation, code including non-transactional memory accesses that are to conflict with transactional memory accesses is patched to insert transactional barriers at the conflicting non-transactional memory accesses to ensure isolation and strong atomicity. However, barriers are omitted or removed from non-transactional memory accesses that do not conflict with transactional memory accesses to reduce barrier execution overhead.
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A method and apparatus to facilitate shared pointers in a heterogeneous platform. In one embodiment of the invention, the heterogeneous or non-homogeneous platform includes, but is not limited to, a central processing core or unit, a graphics processing core or unit, a digital signal processor, an interface module, and any other form of processing cores. The heterogeneous platform has logic to facilitate sharing of pointers to a location of a memory shared by the CPU and the GPU. By sharing… Show more

A method and apparatus to facilitate shared pointers in a heterogeneous platform. In one embodiment of the invention, the heterogeneous or non-homogeneous platform includes, but is not limited to, a central processing core or unit, a graphics processing core or unit, a digital signal processor, an interface module, and any other form of processing cores. The heterogeneous platform has logic to facilitate sharing of pointers to a location of a memory shared by the CPU and the GPU. By sharing pointers in the heterogeneous platform, the data or information sharing between different cores in the heterogeneous platform can be simplified. Show less

A technique for using memory attributes to relay information to a program or other agent. More particularly, embodiments of the invention relate to using memory attribute bits to check various memory properties in an efficient manner.

A method and apparatus for unified concurrency control in a Software Transactional Memory (STM) is herein described. A transaction record associated with a memory address referenced by a transactional memory access operation includes optimistic and pessimistic concurrency control fields. Access barriers and other transactional operations/functions are utilized to maintain both fields of the transaction record, appropriately. Consequently, concurrent execution of optimistic and pessimistic… Show more

A method and apparatus for unified concurrency control in a Software Transactional Memory (STM) is herein described. A transaction record associated with a memory address referenced by a transactional memory access operation includes optimistic and pessimistic concurrency control fields. Access barriers and other transactional operations/functions are utilized to maintain both fields of the transaction record, appropriately. Consequently, concurrent execution of optimistic and pessimistic transactions is enabled.
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Using cache resident transaction hardware to accelerate a software transactional memory system. The method includes identifying a plurality of atomic operations intended to be performed by a software transactional memory system as transactional operations as part of a software transaction. The method further includes selecting at least a portion of the plurality of atomic operations. The method further includes attempting to perform the portion of the plurality of atomic operations as hardware… Show more

Using cache resident transaction hardware to accelerate a software transactional memory system. The method includes identifying a plurality of atomic operations intended to be performed by a software transactional memory system as transactional operations as part of a software transaction. The method further includes selecting at least a portion of the plurality of atomic operations. The method further includes attempting to perform the portion of the plurality of atomic operations as hardware transactions using cache resident transaction hardware.
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A method and apparatus for accelerating transactional execution. Barriers associated with shared memory lines referenced by memory accesses within a transaction are only invoked/executed the first time the shared memory lines are accessed within a transaction. Hardware support, such as a transaction field/transaction bits, are provided to determine if an access is the first access to a shared memory line during a pendancy of a transaction. Additionally, in an aggressive operational mode version… Show more

A method and apparatus for accelerating transactional execution. Barriers associated with shared memory lines referenced by memory accesses within a transaction are only invoked/executed the first time the shared memory lines are accessed within a transaction. Hardware support, such as a transaction field/transaction bits, are provided to determine if an access is the first access to a shared memory line during a pendancy of a transaction. Additionally, in an aggressive operational mode version numbers representing versions of elements stored in shared memory lines are not stored and validated upon commitment to save on validation costs. Moreover, even in a cautious mode, that stores version numbers to enable validation, validation costs may not be incurred, if eviction of accessed shared memory lines do not occur during execution of the transaction.
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A method includes receiving control in a kernel mode via a ring transition from a user thread during execution of an unbounded transactional memory (UTM) transaction, updating a state of a transaction status register (TSR) associated with the user thread and storing the TSR with a context of the user thread, and later restoring the context during a transition from the kernel mode to the user thread. In this way, the UTM transaction may continue on resumption of the user thread.

Performing non-transactional escape actions within a hardware based transactional memory system. A method includes at a hardware thread on a processor beginning a hardware based transaction for the thread. Without committing or aborting the transaction, the method further includes suspending the hardware based transaction and performing one or more operations for the thread, non-transactionally and not affected by: transaction monitoring and buffering for the transaction, an abort for the… Show more

Performing non-transactional escape actions within a hardware based transactional memory system. A method includes at a hardware thread on a processor beginning a hardware based transaction for the thread. Without committing or aborting the transaction, the method further includes suspending the hardware based transaction and performing one or more operations for the thread, non-transactionally and not affected by: transaction monitoring and buffering for the transaction, an abort for the transaction, or a commit for the transaction. After performing one or more operations for the thread, non-transactionally, the method further includes resuming the transaction and performing additional operations transactionally. After performing the additional operations, the method further includes either committing or aborting the transaction. Show less

In a computing environment, a method of debugging a software application, wherein the software application is configured to use one or more processor caches coupled to a processor in an architecturally significant fashion, the method comprising: beginning execution of the software application at a physical processor; running a debugger while executing the software application at the physical processor; detecting that a portion of the software application causes at least one of reads or writes… Show more

In a computing environment, a method of debugging a software application, wherein the software application is configured to use one or more processor caches coupled to a processor in an architecturally significant fashion, the method comprising: beginning execution of the software application at a physical processor; running a debugger while executing the software application at the physical processor; detecting that a portion of the software application causes at least one of reads or writes to be made to a processor cache in an architecturally significant fashion; and based on detecting that the portion of the software application causes at least one of reads or writes to be made to the processor cache in an architecturally significant fashion, preserving any reads or writes made to the cache in an architecturally significant fashion, while performing debugging operations with the debugger that would ordinarily disturb the reads or writes made to the processor cache in an architecturally significant fashion, including: taking a snapshot of physical processor state of the physical processor and pausing execution of the software application at the physical processor; executing the portion of the software application using a software simulator that simulates the physical processor using the snapshot of physical processor state and that simulates the processor cache, while also performing the debugging operations with the debugger; and subsequent to executing the portion of the software application using the software simulator: applying simulated processor state to the physical processor; and resuming execution of the software application at the physical processor. Show less

Debugging software in systems with architecturally significant processor caches. A method may be practiced in a computing environment. The method includes acts for debugging a software application, wherein the software application is configured to use one or more architecturally significant processor caches coupled to a processor. The method includes beginning execution of the software application. A debugger is run while executing the software application. The software application causes at… Show more

Debugging software in systems with architecturally significant processor caches. A method may be practiced in a computing environment. The method includes acts for debugging a software application, wherein the software application is configured to use one or more architecturally significant processor caches coupled to a processor. The method includes beginning execution of the software application. A debugger is run while executing the software application. The software application causes at least one of reads or writes to be made to the cache in an architecturally significant fashion. The reads or writes made to the cache in an architecturally significant fashion are preserved while performing debugging operations that would ordinarily disturb the reads or writes made to the cache in an architecturally significant fashion. Show less

In a computing environment, a method of debugging a software application, wherein the software application is configured to use one or more processor caches coupled to a processor in an architecturally significant fashion, the method comprising: beginning execution of the software application at a physical processor; running a debugger while executing the software application at the physical processor; detecting that a portion of the software application causes at least one of reads or writes… Show more

In a computing environment, a method of debugging a software application, wherein the software application is configured to use one or more processor caches coupled to a processor in an architecturally significant fashion, the method comprising: beginning execution of the software application at a physical processor; running a debugger while executing the software application at the physical processor; detecting that a portion of the software application causes at least one of reads or writes to be made to a processor cache in an architecturally significant fashion; and based on detecting that the portion of the software application causes at least one of reads or writes to be made to the processor cache in an architecturally significant fashion, preserving any reads or writes made to the cache in an architecturally significant fashion, while performing debugging operations with the debugger that would ordinarily disturb the reads or writes made to the processor cache in an architecturally significant fashion, including: taking a snapshot of physical processor state of the physical processor and pausing execution of the software application at the physical processor; executing the portion of the software application using a software simulator that simulates the physical processor using the snapshot of physical processor state and that simulates the processor cache, while also performing the debugging operations with the debugger; and subsequent to executing the portion of the software application using the software simulator: applying simulated processor state to the physical processor; and resuming execution of the software application at the physical processor. Show less

Various usage models are provided to utilize a Monitor and Call (“mcall”) instruction that incorporates user-level asynchronous signaling. The various usage models utilize the mcall instruction in a multithreading system in order to enhance concurrent thread execution. Other embodiments are also described and claimed.

In one embodiment, the present invention includes a method for accessing a shared memory associated with a reader-writer lock according to a first concurrency mode, dynamically changing from the first concurrency mode to a second concurrency mode, and accessing the shared memory according to the second concurrency mode. In this way, concurrency modes can be adaptively changed based on system conditions. Other embodiments are described and claimed.

Handling garbage collection and exceptions in hardware assisted transactions. Embodiments are practiced in a computing environment including a hardware assisted transaction system. Embodiments includes acts for writing to a card table outside of a transaction; handling garbage collection compaction occurring when a hardware transaction is active by using a common global variable and instructing one or more agents to write to the common global variable any time an operation is performed which… Show more

Handling garbage collection and exceptions in hardware assisted transactions. Embodiments are practiced in a computing environment including a hardware assisted transaction system. Embodiments includes acts for writing to a card table outside of a transaction; handling garbage collection compaction occurring when a hardware transaction is active by using a common global variable and instructing one or more agents to write to the common global variable any time an operation is performed which may change an object's virtual address; acts for managing a thread-local allocation context; acts for handling exceptions while in a hardware assisted transaction. A method includes beginning a hardware assisted transaction, raising an exception while in the hardware assisted transaction, including creating an exception object, determining that the transaction should be rolled back, and as a result of determining that the transaction should be rolled back, marshaling the exception object out of the hardware assisted transaction. Show less

Handling garbage collection and exceptions in hardware assisted transactions. Embodiments are practiced in a computing environment including a hardware assisted transaction system. Embodiments includes acts for writing to a card table outside of a transaction; handling garbage collection compaction occurring when a hardware transaction is active by using a common global variable and instructing one or more agents to write to the common global variable any time an operation is performed which… Show more

Handling garbage collection and exceptions in hardware assisted transactions. Embodiments are practiced in a computing environment including a hardware assisted transaction system. Embodiments includes acts for writing to a card table outside of a transaction; handling garbage collection compaction occurring when a hardware transaction is active by using a common global variable and instructing one or more agents to write to the common global variable any time an operation is performed which may change an object's virtual address; acts for managing a thread-local allocation context; acts for handling exceptions while in a hardware assisted transaction. A method includes beginning a hardware assisted transaction, raising an exception while in the hardware assisted transaction, including creating an exception object, determining that the transaction should be rolled back, and as a result of determining that the transaction should be rolled back, marshaling the exception object out of the hardware assisted transaction.
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Storing metadata that is disjoint from corresponding data by storing the metadata to the same address as the corresponding data but in a different address space. A metadata store instruction includes a storage address for the metadata. The storage address is the same address as that for data corresponding to the metadata, but the storage address when used for the metadata is implemented in a metadata address space while the storage address, when used for the corresponding data is implemented in… Show more

Storing metadata that is disjoint from corresponding data by storing the metadata to the same address as the corresponding data but in a different address space. A metadata store instruction includes a storage address for the metadata. The storage address is the same address as that for data corresponding to the metadata, but the storage address when used for the metadata is implemented in a metadata address space while the storage address, when used for the corresponding data is implemented in a different data address space. As a result of executing the metadata store instruction, the metadata is stored at the storage address. A metadata load instruction includes the storage address for the metadata. As a result of executing the metadata load instruction, the metadata stored at the address is received. Some embodiments may further implement a metadata clear instruction which clears any entries in the metadata address space.
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A method and apparatus for providing optimized strong atomicity operations for non-transactional writes is herein described. Locks are acquired upon initial non-transactional writes to memory locations. The locks are maintained until an event is detected resulting in the release of the locks. As a result, in the intermediary period between acquiring and releasing the locks, any subsequent writes to memory locations that are locked are accelerated through non-execution of lock acquire… Show more

A method and apparatus for providing optimized strong atomicity operations for non-transactional writes is herein described. Locks are acquired upon initial non-transactional writes to memory locations. The locks are maintained until an event is detected resulting in the release of the locks. As a result, in the intermediary period between acquiring and releasing the locks, any subsequent writes to memory locations that are locked are accelerated through non-execution of lock acquire operations.
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In one embodiment, the present invention includes a method for selecting a first transaction execution mode to begin a first transaction in a unbounded transactional memory (UTM) system having a plurality of transaction execution modes. These transaction execution modes include hardware modes to execute within a cache memory of a processor, a hardware assisted mode to execute using transactional hardware of the processor and a software buffer, and a software transactional memory (STM) mode to… Show more

In one embodiment, the present invention includes a method for selecting a first transaction execution mode to begin a first transaction in a unbounded transactional memory (UTM) system having a plurality of transaction execution modes. These transaction execution modes include hardware modes to execute within a cache memory of a processor, a hardware assisted mode to execute using transactional hardware of the processor and a software buffer, and a software transactional memory (STM) mode to execute without the transactional hardware. The first transaction execution mode can be selected to be a highest performant of the hardware modes if no pending transaction is executing in the STM mode, otherwise a lower performant mode can be selected. Other embodiments are described and claimed.
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Minimizing code duplication in an unbounded transactional memory system. A computing apparatus including one or more processors in which it is possible to use a set of common mode-agnostic TM barrier sequences that runs on legacy ISA and extended ISA processors, and that employs hardware filter indicators (when available) to filter redundant applications of TM barriers, and that enables a compiled binary representation of the subject code to run correctly in any of the currently implemented set… Show more

Minimizing code duplication in an unbounded transactional memory system. A computing apparatus including one or more processors in which it is possible to use a set of common mode-agnostic TM barrier sequences that runs on legacy ISA and extended ISA processors, and that employs hardware filter indicators (when available) to filter redundant applications of TM barriers, and that enables a compiled binary representation of the subject code to run correctly in any of the currently implemented set of transactional memory execution modes, including running the code outside of a transaction, and that enables the same compiled binary to continue to work with future TM implementations which may introduce as yet unknown future TM execution modes.
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In one embodiment, the invention provides a method comprising determining metadata encoded in instructions of a stored program; and executing the stored program based on the metadata.

In one embodiment, the present invention includes a method for executing a transactional memory (TM) transaction in a first thread, buffering a block of data in a first buffer of a cache memory of a processor, and acquiring a write monitor on the block to obtain ownership of the block at an encounter time in which data at a location of the block in the first buffer is updated. Other embodiments are described and claimed.

A example method disclosed herein comprises initiating a first optimistically balanced synchronization to acquire a lock of an object, the first optimistically balanced synchronization comprising a first optimistically balanced acquisition and a first optimistically balanced release to be performed on the lock by a same thread and at a same nesting level, releasing the lock after execution of program code covered by the lock if a stored state of the first optimistically balanced release… Show more

A example method disclosed herein comprises initiating a first optimistically balanced synchronization to acquire a lock of an object, the first optimistically balanced synchronization comprising a first optimistically balanced acquisition and a first optimistically balanced release to be performed on the lock by a same thread and at a same nesting level, releasing the lock after execution of program code covered by the lock if a stored state of the first optimistically balanced release indicates that the first optimistically balanced release is still valid, the stored state of the first optimistically balanced release being initialized prior to execution of the program code to indicate that the first optimistically balanced release is valid, and throwing an exception after execution of the program code covered by the lock if the stored state of the first optimistically balanced release indicates that the first optimistically balanced release is no longer valid. Show less

Also with Koichi Yamada, Landy Wang, David Callahan, Vadim Bassim.

Device, system, and method of executing a call to a routine within a transaction. In some embodiments an apparatus may include a memory having stored thereon compiled code corresponding to a transaction, wherein the transaction includes at least one call to a first routine of a pair of first and second mutually inverse routines, and wherein the compiled code includes a call to a first wrapped routine replacing the call to the first routine; and a runtime library including wrapper code, wherein… Show more

Device, system, and method of executing a call to a routine within a transaction. In some embodiments an apparatus may include a memory having stored thereon compiled code corresponding to a transaction, wherein the transaction includes at least one call to a first routine of a pair of first and second mutually inverse routines, and wherein the compiled code includes a call to a first wrapped routine replacing the call to the first routine; and a runtime library including wrapper code, wherein the wrapper code, when executed in response to the call to the first wrapped routine, results in executing the call to the first routine within the transaction and undoing the call to the first routine responsive to abort of the transaction. Other embodiments are described and claimed. Show less

Also with Mike Magruder.

Hardware assisted transactional memory system with open nested transactions. Embodiments include a system whereby hardware acceleration of transactions can be accomplished by implementing open nested transaction in hardware which respect software locks such that a top level transaction can be implemented in software, and thus not be limited by hardware constraints typical when using hardware transactional memory systems.

A method and apparatus for accelerating a software transactional memory (STM) system is described herein. Annotation field are associated with lines of a transactional memory. An annotation field associated with a line of the transaction memory is initialized to a first value upon starting a transaction. In response to encountering a read operation in the transaction, then annotation field is checked. If the annotation field includes a first value, the read is serviced from the line of the… Show more

A method and apparatus for accelerating a software transactional memory (STM) system is described herein. Annotation field are associated with lines of a transactional memory. An annotation field associated with a line of the transaction memory is initialized to a first value upon starting a transaction. In response to encountering a read operation in the transaction, then annotation field is checked. If the annotation field includes a first value, the read is serviced from the line of the transaction memory without having to search an additional write space. A second and third value in the annotation field potentially indicates whether a read operation missed the transactional memory or a tentative value is stored in a write space. Additionally, an additional bit in the annotation field, may be utilized to indicate whether previous read operations have been logged, allowing for subsequent redundant read logging to be reduced. Show less

A method and apparatus for a hybrid transactional memory system is herein described. A first transaction is executed utilizing a first style of a transactional memory system and a second transaction is executed in parallel utilizing a second style of a transactional memory system. For example, a main thread is executed utilizing an update-in place Software Transactional Memory (STM) system while a parallel thread, such as a helper thread, is executed utilizing a write buffering STM. As a… Show more

A method and apparatus for a hybrid transactional memory system is herein described. A first transaction is executed utilizing a first style of a transactional memory system and a second transaction is executed in parallel utilizing a second style of a transactional memory system. For example, a main thread is executed utilizing an update-in place Software Transactional Memory (STM) system while a parallel thread, such as a helper thread, is executed utilizing a write buffering STM. As a result, a main thread may directly update memory locations, while a helper thread's transactional writes are buffered to ensure they do not invalidate transactional reads of the main thread. Therefore, parallel execution of threads is achieved, while ensuring at least one thread, such as a main thread, does not degrade below an amount of execution cycles it would take to execute the main thread serially. Show less

Methods and systems are provided for managing memory allocations and deallocations while in transactional code, including nested transactional code. The methods and systems manage transactional memory operations by using identifiers, such as sequence numbers, to handle memory management in transactions. The methods and systems also maintain lists of deferred actions to be performed at transaction abort and commit times. A number of memory management routines associated with one or more… Show more

Methods and systems are provided for managing memory allocations and deallocations while in transactional code, including nested transactional code. The methods and systems manage transactional memory operations by using identifiers, such as sequence numbers, to handle memory management in transactions. The methods and systems also maintain lists of deferred actions to be performed at transaction abort and commit times. A number of memory management routines associated with one or more transactions examine the transaction sequence number of the current transaction, manipulate commit and/or undo logs, and set/use the transaction sequence number of an associated object, but are not so limited. The methods and systems provide for memory allocation and deallocations within transactional code while preserving transactional semantics. Other embodiments are described and claimed. Show less

Synchronizing threads on loss of memory access monitoring. Using a processor level instruction included as part of an instruction set architecture for a processor, a read, or write monitor to detect writes, or reads or writes respectively from other agents on a first set of one or more memory locations and a read, or write monitor on a second set of one or more different memory locations are set. A processor level instruction is executed, which causes the processor to suspend executing… Show more

Synchronizing threads on loss of memory access monitoring. Using a processor level instruction included as part of an instruction set architecture for a processor, a read, or write monitor to detect writes, or reads or writes respectively from other agents on a first set of one or more memory locations and a read, or write monitor on a second set of one or more different memory locations are set. A processor level instruction is executed, which causes the processor to suspend executing instructions and optionally to enter a low power mode pending loss of a read or write monitor for the first or second set of one or more memory locations. A conflicting access is detected on the first or second set of one or more memory locations or a timeout is detected. As a result, the method includes resuming execution of instructions. Show less

A method and apparatus for fine-grained filtering in a hardware accelerated software transactional memory system is herein described. A data object, which may have any arbitrary size, is associated with a filter word. The filter word is in a first default state when no access, such as a read, from the data object has occurred during a pendancy of a transaction. Upon encountering a first access, such as a first read, from the data object, access barrier operations including an ephemeral/private… Show more

A method and apparatus for fine-grained filtering in a hardware accelerated software transactional memory system is herein described. A data object, which may have any arbitrary size, is associated with a filter word. The filter word is in a first default state when no access, such as a read, from the data object has occurred during a pendancy of a transaction. Upon encountering a first access, such as a first read, from the data object, access barrier operations including an ephemeral/private store operation to set the filter word to a second state are performed. Upon a subsequent/redundant access, such as a second read, the access barrier operations are elided to accelerate the subsequent access, based on the filter word being set to the second state to indicate a previous access occurred. Show less

Thread synchronization methods and apparatus for managed run-time environments are disclosed. An example method to maintain state information for optimistically balanced synchronization of a lock of an object in a managed runtime environment disclosed herein comprises storing state information comprising a state of each pending optimistically balanced release operation corresponding to each pending optimistically balanced synchronization to be performed on the lock of the object, each pending… Show more

Thread synchronization methods and apparatus for managed run-time environments are disclosed. An example method to maintain state information for optimistically balanced synchronization of a lock of an object in a managed runtime environment disclosed herein comprises storing state information comprising a state of each pending optimistically balanced release operation corresponding to each pending optimistically balanced synchronization to be performed on the lock of the object, each pending optimistically balanced synchronization comprising respective paired acquisition and release operations between which an unknown number of unpaired locking operations are to occur, and modifying a first stored state of a first pending optimistically balanced release operation when a subsequent unpaired locking operation is performed on the lock, but not modifying any stored state of any pending optimistically balanced release, including the first stored state of a first pending optimistically balanced release operation, when a subsequent optimistically balanced synchronization is performed on the lock.
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A method and apparatus for ensuring integrity of transaction exit functions is herein described. Dead local data in a transaction is prevented from overwriting local variables associated with a transaction exit function. In a write-buffering Software Transactional Memory (STM) system, a commit function is associated with a private stack to store local variables to ensure write-back of local dead data in a write-buffer does not corrupt the commit function. Similarly, in a roll-back STM, an abort… Show more

A method and apparatus for ensuring integrity of transaction exit functions is herein described. Dead local data in a transaction is prevented from overwriting local variables associated with a transaction exit function. In a write-buffering Software Transactional Memory (STM) system, a commit function is associated with a private stack to store local variables to ensure write-back of local dead data in a write-buffer does not corrupt the commit function. Similarly, in a roll-back STM, an abort function is associated with a private stack to store local variables to ensure the roll-back of a program stack with local dead data from a write log does not corrupt the abort function. Alternatively, one stack may be used for the transaction including a first function and an exit function. Here, local dead variables are detected and prevented from overwriting local variables of the exit function.
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A transactional memory system, method and apparatus are disclosed. An embodiment of the method includes attempting to acquire a write lock provided by an implementation of a software transactional memory (STM) system for each of a set of memory locations of the STM; if a write lock is acquired for each of the set of memory locations, comparing the value in each of the set of memory locations to a corresponding expected value; and if the comparing yields the same, predetermined result for each… Show more

A transactional memory system, method and apparatus are disclosed. An embodiment of the method includes attempting to acquire a write lock provided by an implementation of a software transactional memory (STM) system for each of a set of memory locations of the STM; if a write lock is acquired for each of the set of memory locations, comparing the value in each of the set of memory locations to a corresponding expected value; and if the comparing yields the same, predetermined result for each of the set of memory locations, storing in each memory location a corresponding new value. Other embodiments are also described and claimed.
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Also with Mike Magruder, Matt Tolton, Vadim Bassim.

In accordance with some embodiments, software transactional memory may be used for both managed and unmanaged environments. If a cache line is resident in a cache and this is not the first time that the cache line has been read since the last write, then the data may be read directly from the cache line, improving performance. Otherwise, a normal read may be utilized to read the information. Similarly, write performance can be accelerated in some instances to improve performance.

A method and apparatus for efficient and consistent validation/conflict detection in a Software Transactional Memory (STM) system is herein described. A version check barrier is inserted after a load to compare versions of loaded values before and after the load. In addition, a global timestamp (GTS) is utilized to track a latest committed transaction. Each transaction is associated with a local timestamp (LTS) initialized to the GTS value at the start of a transaction. As a transaction commits… Show more

A method and apparatus for efficient and consistent validation/conflict detection in a Software Transactional Memory (STM) system is herein described. A version check barrier is inserted after a load to compare versions of loaded values before and after the load. In addition, a global timestamp (GTS) is utilized to track a latest committed transaction. Each transaction is associated with a local timestamp (LTS) initialized to the GTS value at the start of a transaction. As a transaction commits it updates the GTS to a new value and sets versions of modified locations to the new value. Pending transactions compare versions determined in read barriers to their LTS. If the version is greater than their LTS indicating another transaction has committed after the pending transaction started and initialized the LTS, then the pending transaction validates its read set to maintain efficient and consistent transactional execution. Show less

A method for managing a transaction includes determining that an optimistically immutable field in the transaction is written to. Invaliding a method in response to determining that the method in the transaction reads is the optimistically immutable field.
Other embodiments are disclosed and claimed.

For a variable accessed at least once in a software-based transactional memory system (STM) defined (STM-defined) critical region of a program, modifying an access to the variable that occurs outside any STM-defined critical region system by starting a hardware based transactional memory based transaction, within the hardware based transactional memory based transaction, checking if the variable is currently owned by a STM transaction, checking if the variable is currently owned by a STM… Show more

For a variable accessed at least once in a software-based transactional memory system (STM) defined (STM-defined) critical region of a program, modifying an access to the variable that occurs outside any STM-defined critical region system by starting a hardware based transactional memory based transaction, within the hardware based transactional memory based transaction, checking if the variable is currently owned by a STM transaction, checking if the variable is currently owned by a STM transaction; if the variable is not currently owned by a STM transaction, performing the access and then committing the hardware based transactional memory transaction; and if the variable is currently owned by a STM transaction, performing a responsive action. Show less

Provided is a method, system, and program for coordinating access to memory locations for hardware transactional memory transactions and software transactional memory transactions. A hardware transaction executing in hardware transactional memory initiates a request to access a memory location. A fault is returned to the hardware transaction request in response to an operation by one software transaction executing in a software transactional memory.

Methods and apparatus are disclosed to tune intermediate representations in a managed runtime environment. An example method disclosed herein receives a bytecode at a virtual machine during runtime, determines a method of the received bytecode, identifies an optimized intermediate representation associated with the method, and imports the optimized intermediate representation from the memory into the virtual machine. Other embodiments are described and claimed.

A method and apparatus for efficiently executing nested transactions is herein described. Hardware support for execution of transactions is provided. Additionally, through the use of logging previous values immediately before a current nested transaction in a local memory and storage of a stack of handlers associated with a hierarchy of transactions, nested transactions are potentially efficiently executed. Upon a failure, abort, or invalidating event/access within a nested transaction, the… Show more

A method and apparatus for efficiently executing nested transactions is herein described. Hardware support for execution of transactions is provided. Additionally, through the use of logging previous values immediately before a current nested transaction in a local memory and storage of a stack of handlers associated with a hierarchy of transactions, nested transactions are potentially efficiently executed. Upon a failure, abort, or invalidating event/access within a nested transaction, the state of variables or memory locations written to during execution of the nested transaction are rolled-back to immediately before the nested transaction, instead of all the way back to an original state of the variables or memory locations before an enclosing transaction. As a result, nested transactions may be re-executed within enclosing transactions, without flattening the enclosing and nested transactions to re-execute everything. Show less

A method and apparatus for efficiently executing nested transactions is herein described. Hardware support for execution of transactions is provided. Additionally, through the use of logging previous values immediately before a current nested transaction in a local memory and storage of a stack of handlers associated with a hierarchy of transactions, nested transactions are potentially efficiently executed. Upon a failure, abort, or invalidating event/access within a nested transaction, the… Show more

A method and apparatus for efficiently executing nested transactions is herein described. Hardware support for execution of transactions is provided. Additionally, through the use of logging previous values immediately before a current nested transaction in a local memory and storage of a stack of handlers associated with a hierarchy of transactions, nested transactions are potentially efficiently executed. Upon a failure, abort, or invalidating event/access within a nested transaction, the state of variables or memory locations written to during execution of the nested transaction are rolled-back to immediately before the nested transaction, instead of all the way back to an original state of the variables or memory locations before an enclosing transaction. As a result, nested transactions may be re-executed within enclosing transactions, without flattening the enclosing and nested transactions to re-execute everything.
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Methods and apparatus to dynamically insert prefetch instructions are disclosed. In an example method, one or more samples associated with cache misses are identified from a performance monitoring unit in a processor system. Based on sample information associated with the one or more samples, delinquent information is generated. To dynamically insert one or more prefetch instructions, a prefetch point is identified based on the delinquent information.

Thread synchronization with lock inflation methods and apparatus for managed run-time environments are disclosed. An example method disclosed herein comprises determining a locking operation to perform on a lock corresponding to the object, performing an optimistically balanced synchronization of the lock if the locking operation is not unbalanced, and modifying a lock shape of the lock if the locking operation is unbalanced.

Embodiments of a system and method for transactional memory (TM) with automatic object versioning are described. Embodiments described herein include a TM system and method that facilitates the execution of object-oriented application programs in a transactional environment, including automatically versioning objects to enhance efficiency. Embodiments of the TM automatically designate versions of objects using pointers, accurately identifying usable and unusable versions. Object versioning as… Show more

Embodiments of a system and method for transactional memory (TM) with automatic object versioning are described. Embodiments described herein include a TM system and method that facilitates the execution of object-oriented application programs in a transactional environment, including automatically versioning objects to enhance efficiency. Embodiments of the TM automatically designate versions of objects using pointers, accurately identifying usable and unusable versions. Object versioning as described herein allows the garbage collector to easily and efficiently determine which objects may be moved, freeing memory space and reducing the number of objects traversed by a transaction before finding a useable version of an object. Other embodiments are described and claimed.
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A memory controller is described that comprises a compression map cache. The compression map cache is to store information that identifies a cache line's worth of information that has been compressed with another cache line's worth of information. A processor and a memory controller integrated on a same semiconductor die is also described. The memory controller comprises a compression map cache. The compression map cache is to store information that identifies a cache line's worth of… Show more

A memory controller is described that comprises a compression map cache. The compression map cache is to store information that identifies a cache line's worth of information that has been compressed with another cache line's worth of information. A processor and a memory controller integrated on a same semiconductor die is also described. The memory controller comprises a compression map cache. The compression map cache is to store information that identifies a cache line's worth of information that has been compressed with another cache line's worth of information. Show less

A method and apparatus for a read barrier mechanism are described. According to an embodiment, a method comprises receiving an access request for a program object; performing a combined check for a null reference or for a read barrier for the program object; and if the combined check is affirmative, performing a recovery operation.

Object-based conflict detection is described in the context of software transactional memory. In one example, a block of instructions is received for execution as an object in a software transactional memory transaction. The base of the object is computed, a lock is found for the object using the base of the object.

Techniques are described for optimizing memory management in a processor system. The techniques may be implemented on processors that include on-chip performance monitoring and on systems where an external performance monitor is coupled to a processor. Processors that include a Performance Monitoring Unit (PMU) are examples. The PMU may store data on read and write cache misses, as well as data on translation lookaside buffer (TLB) misses. The data from the PMU is used to determine if any… Show more

Techniques are described for optimizing memory management in a processor system. The techniques may be implemented on processors that include on-chip performance monitoring and on systems where an external performance monitor is coupled to a processor. Processors that include a Performance Monitoring Unit (PMU) are examples. The PMU may store data on read and write cache misses, as well as data on translation lookaside buffer (TLB) misses. The data from the PMU is used to determine if any memory regions within a memory heap are delinquent memory regions, i.e., regions exhibiting high numbers of memory problems or stalls. If delinquent memory regions are found, the memory manager, such as a garbage collection routine, can efficiently optimize memory performance as well as the mutators performance by improving the layout of objects in the heap. In this way, memory management routines may be focused based on dynamic and real-time memory performance data. Show less

The present disclosure relates to the allocation of registers the scheduling of instructions, and, more specifically, to the classifying of operands and allocation of registers to local operands.

Memory reclamation with optimistic concurrency is described. In one example an allocated memory object is tentatively freed in a software transactional memory, the object having pointers into it from at least one transaction. A time when all transactions that are outstanding at the time an object is tentatively freed have ended is detected, and the object is actually freed based on the detection.

Methods and apparatus to insert prefetch instructions based on garbage collector analysis and compiler analysis are disclosed. In an example method, one or more batches of samples associated with cache misses from a performance monitoring unit in a processor system are received. One or more samples from the one or more batches of samples based on delinquent information are selected. A performance impact indicator associated with the one or more samples is generated. Based on the performance… Show more

Methods and apparatus to insert prefetch instructions based on garbage collector analysis and compiler analysis are disclosed. In an example method, one or more batches of samples associated with cache misses from a performance monitoring unit in a processor system are received. One or more samples from the one or more batches of samples based on delinquent information are selected. A performance impact indicator associated with the one or more samples is generated. Based on the performance indicator, at least one of a garbage collector analysis and a compiler analysis is initiated to identify one or more delinquent paths. Based on the at least one of the garbage collector analysis and the compiler analysis, one or more prefetch points to insert prefetch instructions are identified.
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A method, apparatus and system including selecting a phase threshold value, receiving a plurality of sequenced buffers, determining a distance between centers of at least two consecutive histogram bins, comparing the distance with the selected threshold value, and determining major execution phases of an executable process based on the comparison.

Apparatus and methods for optimizing an operating speed and size of a computer program are disclosed. In an example, an apparatus includes an execution module to run a computer program, an exception detector to detect throws to an exception handler and to detect locations from which the throws occur, a memory to store data developed by the exception detector and a code adjuster to at least one of inline and fold the exception handler with respect to at least one of the detected locations.

A system includes a processor and a size bounded first-in first-out (FIFO) memory that is connected to the processor and a display is connected to the processor. A managing process to run on the processor to manage the FIFO memory structure. The FIFO memory includes a counter portion and a value portion for each of a tail portion and a head portion, and the managing process is non-blocking. The counter portion is used as a timestamp to maintain FIFO order.

Cache coherency rules for a multi-processor computing system that is capable of working with compressed cache lines' worth of information are described. A multi-processor computing system that is capable of working with compressed cache lines' worth of information is also described. The multi-processor computing system includes a plurality of hubs for communicating with various computing system components and for compressing/decompressing cache lines' worth of information. A processor that is… Show more

Cache coherency rules for a multi-processor computing system that is capable of working with compressed cache lines' worth of information are described. A multi-processor computing system that is capable of working with compressed cache lines' worth of information is also described. The multi-processor computing system includes a plurality of hubs for communicating with various computing system components and for compressing/decompressing cache lines' worth of information. A processor that is capable of labeling cache lines' worth of information in accordance with the cache coherency rules is described. A processor that includes a hub as described above is also described.
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In one embodiment, the present invention includes a cache memory having a plurality of cache lines to store data, in which at least some of the cache lines are adapted to store data in a compressed state. The cache memory also may include a first tag corresponding to each of the cache lines to indicate whether data in the corresponding cache line is compressible.

According to one embodiment a computer system is disclosed. The computer system includes a central processing unit (CPU), a cache memory coupled to the CPU and a cache controller, coupled to the cache memory. The cache memory includes a plurality of compressible cache lines to store additional data. The cache controller reorders a cache line after each access to the cache line prior to the compression of the cache line into a compressed cache line.

According to one embodiment a computer system is disclosed. The computer system includes a central processing unit (CPU), a cache memory coupled to the CPU and a cache controller coupled to the cache memory. The cache memory includes a plurality of compressible cache lines to store additional data. The cache controller includes compression logic to compress one or more of the plurality of cache lines into compressed cache lines, and hint logic to store hint information in unused space within… Show more

According to one embodiment a computer system is disclosed. The computer system includes a central processing unit (CPU), a cache memory coupled to the CPU and a cache controller coupled to the cache memory. The cache memory includes a plurality of compressible cache lines to store additional data. The cache controller includes compression logic to compress one or more of the plurality of cache lines into compressed cache lines, and hint logic to store hint information in unused space within the compressed cache lines. Show less

A computer system includes a central processing unit (CPU) and a cache memory coupled to the CPU. The cache memory includes a plurality of compressible cache lines to store additional data.

Methods and apparatuses for dynamic type checking are described. For one embodiment runtime code generation is used to effect dynamic type checking by generating code specialized to different object types. For one embodiment a virtual dynamic type check (DTC) function is generated for each object at run time. The virtual DTC function contains a sequence of instructions to type check every element (type) within an object's type hierarchy. The virtual DTC function is tailored for a particular… Show more

Methods and apparatuses for dynamic type checking are described. For one embodiment runtime code generation is used to effect dynamic type checking by generating code specialized to different object types. For one embodiment a virtual dynamic type check (DTC) function is generated for each object at run time. The virtual DTC function contains a sequence of instructions to type check every element (type) within an object's type hierarchy. The virtual DTC function is tailored for a particular type and thus conducts dynamic type checking more efficiently for objects of the particular type. For one embodiment the DTC function can complete type checking of interface type hierarchies. For one embodiment a compiler may determine whether a type is a class type or interface type and may generate a virtual DTC function only for interface types. Show less

A system and method for exception handling includes executing a first instruction. The first instruction then returns an exception. A program counter is used to determine the location of a second instruction. The second instruction includes a pointer to at least one exception handler.

A hierarchical software profiling mechanism that gathers hierarchical path profile information has been described. Software to be profiled is instrumented with instructions that save an outer path sum when an inner region is entered, and restore the outer path sum when the inner region is exited. When the inner region is being executed, an inner path sum is generated and a profile indicator representing the inner path traversed is updated prior to the outer path sum being restored. The software… Show more

A hierarchical software profiling mechanism that gathers hierarchical path profile information has been described. Software to be profiled is instrumented with instructions that save an outer path sum when an inner region is entered, and restore the outer path sum when the inner region is exited. When the inner region is being executed, an inner path sum is generated and a profile indicator representing the inner path traversed is updated prior to the outer path sum being restored. The software to be profiled is instrumented using information from augmented control flow graphs that represent the software. Show less

Many programming languages utilize reference pointers in computer code. Furthermore, some of these programming languages perform memory management in the form of garbage collection. Once such language is Java. During the execution of a garbage collection routine, the computer may need to locate all the variables containing reference values. The present invention introduces a method for run-time tracking of object references in computer code and determining which variables contain references to… Show more

Many programming languages utilize reference pointers in computer code. Furthermore, some of these programming languages perform memory management in the form of garbage collection. Once such language is Java. During the execution of a garbage collection routine, the computer may need to locate all the variables containing reference values. The present invention introduces a method for run-time tracking of object references in computer code and determining which variables contain references to objects at garbage collection sites. The method of the present invention first creates a bit vector in memory. The bit vector is then initialized. Second, each variable declared in the computer program that may be used to store a reference value is assigned a unique bit within this bit vector. Each bit is maintained to indicate whether the variable it is assigned to is currently storing a reference value. Specifically, when a variable is assigned a reference value, the corresponding bit in the bit vector is set. When a variable is assigned a non-reference value, the corresponding bit in the bit vector is cleared. Show less

To efficient generate native processor code from operand stack based code, a mimic stack is introduced. The mimic stack is a compile time data structure that stores the location of operands pushed onto the operand stack. When an operation is detected that operates on operand stack values, the locations from the mimic stack are popped off and used to generate efficient code that directly accesses the operands.

Early Java Virtual Machine implementations executed Java programs very slowly since the Java byte codes were interpreted. Later, Java compilers were introduced to improve performance. To further improve performance, the present invention introduces a method of dynamically optimizing computer code. The method of the present invention first compiles Java byte code into an object code. While compiling, the method introduces instrumentation code into the object code that performs path profiling… Show more

Early Java Virtual Machine implementations executed Java programs very slowly since the Java byte codes were interpreted. Later, Java compilers were introduced to improve performance. To further improve performance, the present invention introduces a method of dynamically optimizing computer code. The method of the present invention first compiles Java byte code into an object code. While compiling, the method introduces instrumentation code into the object code that performs path profiling. Specifically, the path profiling instrumentation code determines which execution paths are executed most often by counting the number of times each possible execution path is executed. When a particular execution path exceeds a threshold value, then that execution path is deemed a “hot” execution path. The hot execution path is then dynamically optimized. The optimized hot path is then executed instead of the original compiled object code for improved performance. Show less

Compilers are tools that generate efficient mappings from programs to machines. A Java "Just-In-Time" runs as part of an application, and as such, it must be fast and efficient in its use of memory. To achieve good performance and further optimize code generation, the present invention introduces a method for eliminating common subexpressions from Java bytecodes. The method of the present invention first loads a code stream containing sequences of computer code into computer memory. The… Show more

Compilers are tools that generate efficient mappings from programs to machines. A Java "Just-In-Time" runs as part of an application, and as such, it must be fast and efficient in its use of memory. To achieve good performance and further optimize code generation, the present invention introduces a method for eliminating common subexpressions from Java bytecodes. The method of the present invention first loads a code stream containing sequences of computer code into computer memory. The expression value for a first expression of a first code sequence is computed and stored in a memory location. A tag is assigned to the memory location holding this expression value for tracking which expression sequences' values are held in memory locations. As code compilation continues, the code selector looks ahead in the code stream to see if any upcoming expression sequences already have expression values stored in a memory location. The code selector compares the expression of a second code sequence with the code sequences annotated by the tags of expression values currently stored in memory. If the second code sequence matches a sequence already associated with a memory location, then the value of the matched sequence is pushed from the memory location onto a stack, and the computations of the expression of the second code sequence is skipped. If the second expression does not match any of the expressions represented by the tags, the expression value of the second expression is calculated and stored in a memory location. This memory location is then annotated with its own expression tag for future comparisons with upcoming expressions in the code stream. Show less

Many programming languages utilize reference pointers in computer code. Furthermore, some of these programming languages perform memory management in the form of garbage collection. Once such language is Java. During the execution of a garbage collection routine, the computer may need to locate all the variables containing reference values. The present invention introduces a method for run-time tracking of object references in computer code and determining which variables contain references to… Show more

Many programming languages utilize reference pointers in computer code. Furthermore, some of these programming languages perform memory management in the form of garbage collection. Once such language is Java. During the execution of a garbage collection routine, the computer may need to locate all the variables containing reference values. The present invention introduces a method for run-time tracking of object references in computer code and determining which variables contain references to objects at garbage collection sites. The method of the present invention first creates a bit vector in memory. The bit vector is then initialized. Second, each variable declared in the computer program that may be used to store a reference value is assigned a unique bit within this bit vector. Each bit is maintained to indicate whether the variable it is assigned to is currently storing a reference value. Specifically, when a variable is assigned a reference value, the corresponding bit in the bit vector is set. When a variable is assigned a non-reference value, the corresponding bit in the bit vector is cleared. Show less