Intel Corporation

Universiteit Gent

Wim Heirman

Ibrahim Hur

Stijn Eyerman

Kristof Du Bois

Yves Vandriessche

Joshua B Fryman

Ugonna C Echeruo

Ankit More

Jason M Howard

Robert Pawlowski

Erik Hallnor

Shaden Smith

Lieven Eeckhout

Scott Cline

Trevor E Carlson

Scott Hagan Schmittel

Methods and apparatus relating to one or more delayed cache writeback instructions for improved data sharing in manycore processors are described. In an embodiment, a delayed cache writeback instruction causes a cache block in a modified state in a Level 1 (L1) cache of a first core of a plurality of cores of a multi-core processor to a Modified write back (M.wb) state. The M.wb state causes the cache block to be written back to LLC upon eviction of the cache block from the L1 cache. Other embodiments are also disclosed and claimed.

Delayed cache writeback instructions for improved data sharing in manycore processors

Techniques and mechanisms for providing information to determine whether a software prefetch instruction is to be executed. In an embodiment, one or more entries of a translation lookaside buffer (TLB) each include a respective value which indicates whether, according to one or more criteria, corresponding data has been sufficiently utilized. Insufficiently utilized data is indicated in a TLB entry with an identifier of an executed instruction to prefetch the corresponding data. An eviction of the TLB entry results in the creation of an entry in a registry of prefetch instructions. The entry in the registry includes the identifier of the executed prefetch instruction, and a value indicating a number of times that one or more future prefetch instructions are to be dropped. In another embodiment, execution of a subsequent prefetch instruction—which also corresponds to the identifier—is prevented based on the registry entry.

Device, system and method for selectively dropping software prefetch instructions

In an embodiment, a processor includes a fetch circuit to fetch instructions, the instructions including a code prefetch instruction; a decode circuit to decode the code prefetch instruction and provide the decoded code prefetch instruction to a memory circuit, the memory circuit to execute the decoded code prefetch instruction to prefetch a first set of code blocks into a first cache and to prefetch a second set of code blocks into a second cache. Other embodiments are described and claimed.

Instruction and logic for code prefetching

Apparatus, method, and system for enhancing data prefetching based on non-uniform memory access (NUMA) characteristics are described herein. An apparatus embodiment includes a system memory, a cache, and a prefetcher. The system memory includes multiple memory regions, at least some of which are associated with different NUMA characteristic (access latency, bandwidth, etc.) than others. Each region is associated with its own set of prefetch parameters that are set in accordance to their respective NUMA characteristics. The prefetcher monitors data accesses to the cache and generates one or more prefetch requests to fetch data from the system memory to the cache based on the monitored data accesses and the set of prefetch parameters associated with the memory region from which data is to be fetched. The set of prefetcher parameters may include prefetch distance, training-to-stable threshold, and throttle threshold.

Apparatus, method, and system for enhanced data prefetching based on non-uniform memory access (NUMA) characteristics

A method for simulating a set of instructions to be executed on a processor including performing a performance simulation of the processor over a number of simulation cycles. Modeling, in a frontend component, branch prediction and instruction cache is performed providing instructions to the instruction window, and modeling of an instruction window for the cycle is performed. From the simulation, a performance parameter of the processor is obtained without modeling a reorder buffer, issue queue(s), register renaming, load-store queue(s) and other buffers of the processor.

Instruction window centric processor simulation

In one embodiment, an apparatus includes a memory access circuit to receive memory access instructions and provide at least some of the memory access instructions to a memory subsystem for execution. The memory access circuit may have a conversion circuit to convert the first memory access instruction to a first subline memory access instruction, e.g., based at least in part on an access history for a first memory access instruction. Other embodiments are described and claimed.

System, apparatus and method for dynamic automatic sub-cacheline granularity memory access control

Disclosed embodiments relate to systems and methods for performing instructions to access a compressed graphic list. In one example, a processor includes fetch and decode circuitry to fetch and decode the single instruction to access the compressed graphic list, and execution circuitry to execute the decoded single instruction to cause access to the compressed graphic list by: receiving, from a load store queue, at a first op-engine associated with a first data location, an indirection request, computing, via the first op-engine, a second data location associated with a second op-engine, computing, via the second op-engine, a third data location associated with a third op-engine responsive to the indirection request, and providing, via the third op-engine, a data response to the load store queue responsive to receiving data from the third data location.

Systems and methods for ISA support for indirect loads and stores for efficiently accessing compressed lists in graph applications

Embodiment of this disclosure provides a mechanism to store cache lines in dedicated cache of an idle core. In one embodiment, a multi-core processor comprising a first core, a second core, a first cache, a second cache, a third cache, and a cache controller unit is provided. The cache controller is operatively coupled to at least the first cache, the second cache, and the third cache. The cache controller is to evict a first line from the first cache, wherein the first core is in an active state. Responsive to the evicting of the first line, the first line is stored in the third cache. Responsive to storing the first line, a second line is evicted from the third cache. Responsive to evicting the second line, the second line is stored in the second cache when the second core is in an idle state.

Storing cache lines in dedicated cache of an idle core

Disclosed embodiments relate to an indirect memory fetch (IMF) unit. In one example, an apparatus includes circuitry to fetch and decode an instruction specifying a sparse operand array including N operands, and an index array including N contiguously-addressed indices. The apparatus further includes a processing engine associated with an IMF unit to respond to the decoded instruction by initializing the IMF unit to fetch the N operands in order, probing the IMF unit to determine that a fetched operand is ready to retrieve, retrieving the fetched operand from the IMF unit, and repeating the probing and retrieving until all N operands have been retrieved. The IMF unit, independent of the processing engine, is to fetch the N contiguously-addressed indices from the index array, use the N fetched indices to calculate memory addresses for the N operands, and issue a plurality of read requests to fetch the N operands in order.

Indirect memory fetcher

An example processor that includes a register, a cache, a processor core, and a programmable logic circuit. The register may store a first prefetch value indicating a first amount of time to prefetch data from a memory prior to an execution of a subsequent instruction that uses the data. The processor core may be coupled to the cache and the register. The processor core may execute a prefetch instruction to access the data from the memory, store a copy of the data in the cache, and execute the subsequent instruction. The programmable logic circuit may be coupled to the processor core. The programmable logic circuit may determine whether the first amount of time is insufficient to prefetch the data for the execution of the subsequent instruction and change the first prefetch value to a second prefetch value when the first amount of time is insufficient.

Prefetching time allocation

A processor core includes a decode circuit to decode an instruction. The processor core further includes a monitor circuit, where the monitor circuit includes a data structure to store a plurality of entries for addresses that are being monitored by the monitor circuit and a triggered queue to store a plurality of addresses for which a triggering event occurred. The processor core further includes an execution circuit to execute the decoded instruction to dequeue an address from the triggered queue and return the dequeued address in response to a determination that the triggered queue is not empty.

Wait and poll instructions for monitoring a plurality of addresses

Embodiments of apparatuses, methods, and systems for independent tuning of multiple hardware prefetchers are described. In an embodiment, an apparatus includes a processor core, a cache memory, a hardware prefetcher, and a prefetch tuner. The hardware prefetcher is to prefetch data for the processor core from a system memory to the cache memory. The prefetch tuner is to adjust a prefetch rate of the hardware prefetcher based on a fraction of late prefetches. The prefetch tuner includes a late prefetch counter to count a number of late prefetches for the hardware prefetcher, a prefetch counter to count a number of prefetches for the hardware prefetcher, and a late prefetch calculator to calculate the fraction of late prefetches based on the number of late prefetches and the number of prefetches.

Independent tuning of multiple hardware prefetchers

A processor core includes a decode circuit to decode an instruction, where the instruction specifies an address to be monitored. The processor core further includes a monitor circuit, where the monitor circuit includes a data structure to store a plurality of entries for addresses that are being monitored by the monitor circuit and a triggered queue, where the monitor circuit is to enqueue an address being monitored by the monitor circuit into the triggered queue in response to a determination that a triggering event for the address being monitored by the monitor circuit occurred. The processor core further includes an execution circuit to execute the decoded instruction to add an entry for the specified address to be monitored into the data structure and ensure, using a cache coherence protocol, that a coherency status of a cache line corresponding to the specified address to be monitored is in a shared state.

Growing community of inventors

Ghent, Belgium

Wim Heirman