Patent application number | Description | Published |
20140019689 | METHODS OF CACHE PRELOADING ON A PARTITION OR A CONTEXT SWITCH - A scheme referred to as a “Region-based cache restoration prefetcher” (RECAP) is employed for cache preloading on a partition or a context switch. The RECAP exploits spatial locality to provide a bandwidth-efficient prefetcher to reduce the “cold” cache effect caused by multiprogrammed virtualization. The RECAP groups cache blocks into coarse-grain regions of memory, and predicts which regions contain useful blocks that should be prefetched the next time the current virtual machine executes. Based on these predictions, and using a simple compression technique that also exploits spatial locality, the RECAP provides a robust prefetcher that improves performance without excessive bandwidth overhead or slowdown. | 01-16-2014 |
20140075121 | Selective Delaying of Write Requests in Hardware Transactional Memory Systems - Techniques for conflict detection in hardware transactional memory (HTM) are provided. In one aspect, a method for detecting conflicts in HTM includes the following steps. Conflict detection is performed eagerly by setting read and write bits in a cache as transactions having read and write requests are made. A given one of the transactions is stalled when a conflict is detected whereby more than one of the transactions are accessing data in the cache in a conflicting way. An address of the conflicting data is placed in a predictor. The predictor is queried whenever the write requests are made to determine whether they correspond to entries in the predictor. A copy of the data corresponding to entries in the predictor is placed in a store buffer. The write bits in the cache are set and the copy of the data in the store buffer is merged in at transaction commit. | 03-13-2014 |
20140075151 | DETECTION OF CONFLICTS BETWEEN TRANSACTIONS AND PAGE SHOOTDOWNS - There is provided a method for detecting a conflict between a transaction and a TLB (Translation Lookaside Buffer) shootdown in a transactional memory in which a TLB shootdown operation message is received by a processor to invalidate at least one entry in a TLB of the processor corresponding to at least one page. The processor tracks pages touched by the transaction. The processor determines whether the received TLB shootdown operation message is associated with one of the touched pages. The processor aborts the transaction in response to determining that the received TLB shootdown operation message is associated with one of the touched pages. | 03-13-2014 |
20140115297 | DETECTION OF CONFLICTS BETWEEN TRANSACTIONS AND PAGE SHOOTDOWNS - There is provided a system and a computer program product for detecting a conflict between a transaction and a TLB (Translation Lookaside Buffer) shootdown in a transactional memory in which a TLB shootdown operation message is received by a processor to invalidate at least one entry in a TLB of the processor corresponding to at least one page. The processor tracks pages touched by the transaction. The processor determines whether the received TLB shootdown operation message is associated with one of the touched pages. The processor aborts the transaction in response to determining that the received TLB shootdown operation message is associated with one of the touched pages. | 04-24-2014 |
20140115590 | METHOD AND APPARATUS FOR CONDITIONAL TRANSACTION ABORT AND PRECISE ABORT HANDLING - A method for executing a transaction in a data processing system initiates the transaction by a transactional-memory system coupled to that memory component. The method includes initiating the transaction by a transactional-memory system that is part of a memory component of the data processing system. The transaction includes instructions for comparing multiple parameters, and aborting the transaction by the transactional-memory system based upon a comparison of the multiple parameters. | 04-24-2014 |
20140281710 | TRANSACTIONS FOR CHECKPOINTING AND REVERSE EXECUTION - A method of backstepping through a program execution includes dividing the program execution into a plurality of epochs, wherein the program execution is performed by an active core, determining, during a subsequent epoch of the plurality of epochs, that a rollback is to be performed, performing the rollback including re-executing a previous epoch of the plurality of epochs, wherein the previous epoch includes one or more instructions of the program execution stored by a checkpointing core, and adjusting a granularity of the plurality of epochs according to a frequency of the rollback. | 09-18-2014 |
20150046752 | Redundant Transactions for Detection of Timing Sensitive Errors - A method for detecting a software-race condition in a program includes copying a state of a transaction of the program from a first core of a multi-core processor to at least one additional core of the multi-core processor, running the transaction, redundantly, on the first core and the at least one additional core given the state, outputting a result of the first core and the at least one additional core, and detecting a difference in the results between the first core and the at least one additional core, wherein the difference indicates the software-race condition. | 02-12-2015 |
20150046758 | REDUNDANT TRANSACTIONS FOR SYSTEM TEST - A method for detecting errors in hardware including running a transaction on a plurality of cores, wherein each of the cores runs a respective copy of the transaction, synchronizing the transaction on the cores, comparing results of the transaction on the cores, and determining an error in one or more of the cores. | 02-12-2015 |
20150089152 | MANAGING HIGH-CONFLICT CACHE LINES IN TRANSACTIONAL MEMORY COMPUTING ENVIRONMENTS - Cache lines in a computing environment with transactional memory are configurable with a coherency mode. Cache lines in full-line coherency mode are operated or managed with full-line granularity. Cache lines in sub-line coherency mode are operated or managed as sub-cache line portions of a full cache line. When a transaction accessing a cache line in full-line coherency mode results in a transactional abort, the cache line may be placed in sub-line coherency mode if the cache line is a high-conflict cache line. The cache line may be associated with a counter in a conflict address detection table that is incremented whenever a transaction conflict is detected for the cache line. The cache line may be a high-conflict cache line when the counter satisfies a high-conflict criterion, such as reaching a threshold value. The cache line may be returned to full-line coherency mode when a reset criterion is satisfied. | 03-26-2015 |
20150089153 | IDENTIFYING HIGH-CONFLICT CACHE LINES IN TRANSACTIONAL MEMORY COMPUTING ENVIRONMENTS - Cache lines in a computing environment with transactional memory are configurable with a coherency mode and are associated with a high-conflict indicator. Cache lines in full-line coherency mode are operated or managed with full-line granularity. Cache lines in sub-line coherency mode are operated or managed as sub-cache line portions of a full cache line. A cache line is placed in sub-line coherency mode based on examining the high-conflict indicator. A transaction accessing a memory address in a cache line in sub-line coherency mode marks only the sub-cache line portion associated with the memory address as transactionally accessed. The high-conflict indicator may be included in a set of descriptive bits associated with the cache line. A copy of the high-conflict indicator for a cache line in a first cache may be updated with the high-conflict indicator for the cache line in a second cache. | 03-26-2015 |
20150089154 | MANAGING HIGH-COHERENCE-MISS CACHE LINES IN MULTI-PROCESSOR COMPUTING ENVIRONMENTS - Cache lines in a multi-processor computing environment are configurable with a coherency mode. Cache lines in full-line coherency mode are operated or managed with full-line granularity. Cache lines in sub-line coherency mode are operated or managed as sub-cache line portions of a full cache line. A high-coherence-miss cache line may be placed in sub-line coherency mode. A cache line may be associated with a counter in a coherence miss detection table that is incremented whenever an access of the cache line results in a coherence request. The cache line may be a high-coherence-miss cache line when the counter satisfies a high-coherence-miss criterion, such as reaching a threshold value. The cache line may be returned to full-line coherency mode when a reset criterion is satisfied. | 03-26-2015 |
20150089155 | CENTRALIZED MANAGEMENT OF HIGH-CONTENTION CACHE LINES IN MULTI-PROCESSOR COMPUTING ENVIRONMENTS - Cache lines in a multi-processor computing environment are configurable with a coherency mode. Cache lines in full-line coherency mode are operated or managed with full-line granularity. Cache lines in sub-line coherency mode are operated or managed as sub-cache line portions of a full cache line. Communications detected on a coherence interconnect may indicate that a cache line is associated with performance-reducing events. A high-contention cache line may be placed in sub-line coherency mode. Caches accessing the cache line are notified that the cache line is in sub-line coherency mode. The cache line may be associated with a counter in a centralized detection table that is incremented based on detecting the communications. The cache line may be a high-contention cache line when the counter satisfies a high-contention criterion, such as reaching a threshold value. The cache line may be returned to full-line coherency mode when a reset criterion is satisfied. | 03-26-2015 |
20150089159 | MULTI-GRANULAR CACHE MANAGEMENT IN MULTI-PROCESSOR COMPUTING ENVIRONMENTS - Cache lines in a multi-processor computing environment are configurable with a coherency mode. Cache lines in full-line coherency mode are operated or managed with full-line granularity. Cache lines in sub-line coherency mode are operated or managed as sub-cache line portions of a full cache line. Each cache is associated with a directory having a number of directory entries and with a side table having a smaller number of entries. The directory entry for a cache line associates the cache line with a tag and a set of full-line descriptive bits. Creating a side table entry for the cache line places the cache line in sub-line coherency mode. The side table entry associates each of the sub-cache line portions of the cache line with a set of sub-line descriptive bits. Removing the side table entry may return the cache line to full-line coherency mode. | 03-26-2015 |