160 results about "Simultaneous multithreading" patented technology

A thread scheduling mechanism is provided that flexibly enforces performance isolation of multiple threads to alleviate the effect of anti-cooperative execution behavior with respect to a shared resource, for example, hoarding a cache or pipeline, using the hardware capabilities of simultaneous multi-threaded (SMT) or multi-core processors. Given a plurality of threads running on at least two processors in at least one functional processor group, the occurrence of a rescheduling condition indicating anti-cooperative execution behavior is sensed, and, if present, at least one of the threads is rescheduled such that the first and second threads no longer execute in the same functional processor group at the same time.

A method and logical apparatus for rename register reallocation in a simultaneous multi-threaded (SMT) processor provides a mechanism for redistributing rename (mapped) resources between one thread during single-threaded (ST) execution and multiple threads during multi-threaded execution. The processor receives an instruction specifying a transition from a single-threaded to a multi-threaded mode or vice-versa and halts execution of all threads executing on the processor. The internal control logic then signals the resources to reallocate the resources. Rename resources are reallocated by directing an action at the rename mapper. Specifically, on a switch from SMT to ST mode, the mapper is directed to drop entries for the dying thread, but on a switch from ST to SMT mode, "dummy" instruction group dispatch indications are sent to the mapper that indicate use of all registers, so that mapper entries are deleted from the pool of entries used by the previously-executing "surviving" thread to make room for rename entries needed by another "reviving" thread that is being started for further execution in SMT mode.

An accounting method and logic for determining per-thread processor resource utilization in a simultaneous multi-threaded (SMT) processor provides a mechanism for accounting for processor resource usage by programs and threads within programs. Relative resource use is determined by detecting instruction dispatches for multiple threads active within the processor, which may include idle threads that are still occupying processor resources. If instructions are dispatched for all threads or no threads, the processor cycle is accounted equally to all threads. Alternatively if no threads are in a dispatch state, the accounting may be made using a prior state, or in conformity with ratios of the threads' priority levels. If only one thread is dispatching, that thread is accounted the entire processor cycle. If multiple threads are dispatching, but less than all threads are dispatching (in processors supporting more than two threads), the processor cycle is billed evenly across the dispatching threads. Multiple dispatches may be detected for the threads and a fractional resource usage determined for each thread and the counters may be updated in accordance with their fractional usage.

A method and apparatus are provided for implementing a variable-partitioned queue for simultaneous multithreaded processors. A value is stored in a partition register. A queue structure is divided between a plurality of threads responsive to the stored value in the partition register. When a changed value is received for storing in the partition register, the queue structure is divided between the plurality of threads responsive to the changed value.

A document management system and method are provided to support simultaneous multi-user editing of a single document. The system and method do not require the use of a new file format or the use of a central document repository to limit user access to the document. When a user attempts to open the document and a determination is made that the document is in use, then an alert is presented to the user that informs the user that the document is locked for editing. The user may select to receive a notification when the original document is no longer in use. If the user selects to make a local copy and subsequently merge the changes, the local copy will be made and the path of the original document will be stored so that the original document location can be determined at the time that the changes are merged. When the original document becomes available, the user's changes can be merged into the original document. The original document is located using the original path that was stored when the local copy was created. Of course, any time that a merge is attempted, and a conflict exists (i.e., the changes in the local document are inconsistent with the changes made to the original document), an alert can be generated to inform the user of the conflict and the user can be prompted to reconcile the conflict to complete the merge.

A method and logical apparatus for managing thread execution within a simultaneous multi-threaded (SMT) processor provides a mechanism for switching between single-threaded and multi-threaded execution. The processor receives an instruction specifying a transition from a single-threaded to a multi-threaded mode or vice-versa and halts execution of all threads executing on the processor. Internal control logic controls a sequence of events that ends instruction prefetching, dispatch of new instructions, interrupt processing and maintenance operations and waits for operation of the processor to complete for instructions that are in process. Then, the logic determines one or more threads to start in conformity with a thread enable state specifying the enable state of multiple threads and reallocates various resources, dividing them between threads if multiple threads are specified for further execution (multi-threaded mode) or allocating substantially all of the resources to a single thread if further execution is specified as single-threaded mode. The processor then starts execution of the remaining enabled threads.

Using resource sets for job-level control of the simultaneous multi-threading capability (SMT) of a processor in a data processing system. A resource set defined with respect to the processor is adapted to control whether the simultaneous multi-threading capability is enabled.

A more efficient method of handling instructions in a computer processor, by associating resource fields with respective program instructions wherein the resource fields indicate which of the processor hardware resources are required to carry out the program instructions, calculating resource requirements for merging two or more program instructions based on their resource fields, and determining resource availability for simultaneously executing the merged program instructions based on the calculated resource requirements. Resource vectors indicative of the required resource may be encoded into the resource fields, and the resource fields decoded at a later stage to derive the resource vectors. The resource fields can be stored in the instruction cache associated with the respective program instructions. The processor may operate in a simultaneous multithreading mode with different program instructions being part of different hardware threads. When the resource availability equals or exceeds the resource requirements for a group of instructions, those instructions can be dispatched simultaneously to the hardware resources. A start bit may be inserted in one of the program instructions to define the instruction group. The hardware resources may in particular be execution units such as a fixed-point unit, a load/store unit, a floating-point unit, or a branch processing unit.

A method for optimizing throughput in a microprocessor that is capable of processing multiple threads of instructions simultaneously. Instruction issue logic is provided between the input buffers and the pipeline of the microprocessor. The instruction issue logic speculatively issues instructions from a given thread based on the probability that the required operands will be available when the instruction reaches the stage in the pipeline where they are required. Issue of an instruction is blocked if the current pipeline conditions indicate that there is a significant probability that the instruction will need to stall in a shared resource to wait for operands. Once the probability that the instruction will stall is below a certain threshold, based on current pipeline conditions, the instruction is allowed to issue.

A method, apparatus, and computer program product are disclosed in a data processing system for sharing data in a cache among multiple threads in a simultaneous multi-threaded (SMT) processor. The SMT processor executes multiple threads concurrently during each clock cycle. The cache is dynamically allocated for use among the multiple threads. Portions of the cache are capable of being designated to store private data that is used exclusively by only a first one of the threads. The portions of the cache are capable of being designated to store shared data that can be used by any one of the multiple threads. The size of the portions can be changed dynamically during execution of the threads.

The invention provides a very long instruction word processor structure supporting simultaneous multithreading, which comprises at least two parallel instruction processing pipeline structures, wherein each instruction processing pipeline structure comprises an instruction obtaining module, an instruction distribution module and an instruction executing module, a general register file, a floating point register file and a control register file, the instruction obtaining module is used for obtaining instruction information, the instruction distribution module is used for receiving and distributing the instruction information obtained by the instruction obtaining module, and the instruction executing module comprises instruction executing units A, D, M and F which are used for executing the instruction information, the general register file is used for storing executing results of the corresponding executing units A, M and D, and the floating point register file is used for storing executing results of the corresponding executing units D and F. Through the structure, the resources of a processor can be more sufficiently utilized, the threading access efficiency is enhanced, and the processing speed of the processor is improved.

The current application is directed to architected hardware support within computer processors for detecting and monitoring various types of potential performance imbalances with respect to simultaneously executing hardware threads in simultaneous multi-threading (“SMT”) processors and SMT-processor cores. The architected hardware support may include various types of performance-imbalance-monitoring registers that accumulate indications of performance imbalances and that can be used, by performance-monitoring software and by human analysts to detect performance-degrading conflicts between simultaneously executing hardware threads. Such conflicts can be ameliorated by changing the scheduling of virtual machines, tasks, and other computational entities, by redesigning and re-implementing all or portions of performance-limited and performance-degrading applications, by altering resource-allocation strategies, and by other means. In addition, performance imbalance detection and monitoring can be used to provide accurate, computational-throughput-based accounting in cloud-computing environments.

A method and multithreaded processor for handling livelocks in a simultaneous multithreaded processor. A number of instructions for a thread in a queue may be counted. A counter in the queue may be incremented if the number of instructions for the thread in the queue in a previous clock cycle is equal to the number of instructions for the thread in the queue in a current clock cycle. If the value of the counter equals a threshold value, then a livelock condition may be detected. Further, if the value of the counter equals a threshold value, a recovery action may be activated to handle the livelock condition detected. The recovery action may include blocking the instructions associated with a thread causing the livelock condition from being executed thereby ensuring that the locked thread makes forward progress.

A system and method for identifying compatible threads in a Simultaneous Multithreading (SMT) processor environment is provided by calculating a performance metric, such as CPI, that occurs when two threads are running on the SMT processor. The CPI that is achieved when both threads were executing on the SMT processor is determined. If the CPI that was achieved is better than the compatibility threshold, then information indicating the compatibility is recorded. When a thread is about to complete, the scheduler looks at the run queue from which the completing thread belongs to dispatch another thread. The scheduler identifies a thread that is (1) compatible with the thread that is still running on the SMT processor (i.e., the thread that is not about to complete), and (2) ready to execute. The CPI data is continually updated so that threads that are compatible with one another are continually identified.

The present invention thus provides for a method, system, and computer-usable medium that afford an equitably charging of a customer for computer usage time. In a preferred embodiment, the method includes the steps of: tracking an amount of computer resources in a Simultaneous Multithreading (SMT) computer that are available to a customer for a specified period of time; determining if the computer resources in the SMT computer are operating at a nominal rate; and in response to determining that the computer resources are operating at a non-nominal rate, adjusting a billing charge to the customer, wherein the billing charge reflects that the customer has available computer resources, in the SMT computer, that are not operating at the nominal rate during the specified period of time.

A method and apparatus for sending thread-execution-state-sensitive supervisory commands to a simultaneous multi-threaded processor provides a mechanism for sending supervisory commands that must be executed for only live threads. The commands may be sent from a service processor or another primary processor in the system or may be supplied by the processor itself through supervisory software control. Since the state of execution of one or more threads may change dynamically within a processor core, an external processor will not know the thread execution state at the time the command operates. The method and apparatus provide a command set and logic that supports selective execution of particular commands directed at "alive" threads (or threads in some other determinable execution state), whereby the command is performed only on resources and/or execution units depending on the actual state of thread execution when the command operates within the processor. The command set and logic further support commands targeting one or all executing threads for commands that are not sensitive to thread execution state.