Apple Inc.

Broadcom Corporation

Teranetics, Inc.

Intel Corporation

Plx Technology, Inc.

Sandeep Kumar Gupta

Greg Marriott

Vivek Venkatraman

Krishna C Potnuru

John Wesley Archibald

Tyler J Huberty

Eric Jason Furbish

David Allan Shayer

Max Sprauer

Shannon E Wells

Jose Tellado

Gerard Richard Williams

Stephan G Meier

Brian P Lilly

Venugopal Gopinathan

Srinivasa Rangan Sridharan

Conrado Blasco-Allue

David Heller

Wei-Han Lien

Pradeep Kanapathipillai

Andrew J Beaumont-Smith

Christopher R Wysocki

James Vash

Matthias Knoth

Amandeep S Jawa

Prashant Jain

Chandan Shantharaj

Stephen G Meier

Sahil Kapoor

James B Keller

Dariush Dabiri

John H Mylius

Sergio Kolor

Ilya Granovsky

Mridul Agarwal

Sanjay Kasturia

Richard F Russo

Conrado Blasco

Shih-Chieh Wen

Rohit Kumar

Szu-Wen Huang

Jason M Kassoff

Rajat Goel

Shyam Sundar

Peter G Soderquist

Oleksiy Zabroda

Suresh B Periyacheri

Perumal R Subramoniam

Tom Greenshtein

Yanran Yang

Yamini Modukuru

Jeff Lee

Oleksly Zabroda

Amanvir Singh Sidana

An apparatus includes a plurality of processor circuits, a cache memory circuit, and a trace control circuit. The trace control circuit may be configured, in response to activation of a mode to record information indicative of program execution of at least one processor circuit of the plurality of processor circuits, to monitor memory requests transmitted between ones of the plurality of processor circuits and the cache memory circuit, and then to select a particular memory request of monitored memory requests using an arbitration algorithm. The trace control circuit may be further configured to allocate space in a trace buffer to the particular memory request, and to store, in the trace buffer, information associated with the particular memory request.

Debug trace of cache memory requests

An apparatus includes a plurality of coherent agents, and a coherence directory that includes directory ways for storing coherency information. The coherence directory may be configured to determine that a cache block that is not currently cached among the coherent agents, is stored in a first coherent agent. The coherence directory may be further configured to, in response to this determination, create a particular entry in a selected one of the directory ways. The coherence directory may also be configured to send, to the first coherent agent, an indicator identifying a directory way that includes the entry. In response to a second coherent agent caching the cache block, the coherence directory may update the entry to include the second coherent agent. The first and second coherent agents may be configured to receive copies of the indicator, and to store their copy in locations associated with the cache block.

Coherence directory way tracking in coherent agents

An apparatus includes a cache memory circuit, a prefetcher circuit, and a prefetch deny list circuit, including a plurality of entries, may be included. The cache memory circuit may be configured to store information retrieved from a lower-level memory. The prefetcher circuit may be configured to generate a prefetch request for a particular prefetch address. The prefetch deny list circuit may be configured to allocate, in response to an indication from the cache memory circuit that a previously prefetched address went unused, a given entry, of the plurality of entries, for the previously prefetched address. The prefetch deny list circuit may be further configured to determine whether a particular address for a particular prefetch request corresponds to an active one of the plurality of entries. In response to a determination that a particular active entry corresponds to the particular address, prefetch deny list circuit may deny the particular prefetch request.

Deny list for a memory prefetcher circuit

Techniques are disclosed pertaining to utilizing a communication fabric via multiple ports. An agent circuit includes a plurality of command-and-data ports that couple the agent circuit to a communication fabric coupled to a plurality of hardware components that includes a plurality of memory controller circuits that facilitate access to a memory. The agent circuit can execute an instruction that involves issuing a command for data stored at the memory. The agent circuit may perform a hash operation on a memory address associated with the command to determine which one of the plurality of memory controller circuits to which to issue the command. The agent circuit issues the command to the determined memory controller circuit on a particular one of the plurality of command-and-data ports that is designated to the memory controller circuit. The agent circuit may issue all commands destined to that memory controller circuit on that port.

Mechanisms to utilize communication fabric via multi-port architecture

A cache may store critical cache lines and non-critical cache lines, and may attempt to retain critical cache lines in the cache by, for example, favoring the critical cache lines in replacement data updates. Multiple levels of criticality may be available for a given cache line and cache circuitry may adjust the criticality value of in response to a criticality event. One or more upper criticality levels may be masked when selecting a victim cache line for replacement.

Criticality-informed caching policies with multiple criticality levels

A cache may include multiple request handling pipes, each of which may further include multiple request buffers, for storing device requests from one or more processors to one or more devices. Some of the device requests may require to be sent to the devices according to an order. For a given one of such device requests, the cache may select a request handling pipe, based on an address indicated by the device request, and select a request buffer, based on the available entries of the request buffers of the selected request handling pipe, to store the device request. The cache may further use a first-level and a second-level token stores to track and maintain the device requests in order when transmitting the device requests to the devices.

Request ordering in a cache

A cache may store critical cache lines and non-critical cache lines, and may attempt to retain critical cache lines in the cache by, for example, favoring the critical cache lines in replacement data updates, retaining the critical cache lines with a certain probability when victim cache blocks are being selected, etc. Criticality values may be retained at various levels of the cache hierarchy. Additionally, accelerated eviction may be employed if the threads previously accessing the critical cache blocks are viewed as dead.

Mitigating retention of previously-critical cache lines

A variable latency cache memory is disclosed. A cache subsystem includes a pipeline control circuit configured to initiate cache memory accesses for data. The cache subsystem further includes a cache memory circuit having a data array arranged into a plurality of groups, wherein different ones of the plurality of groups have different minimum access latencies due to different distances from the pipeline control circuit. A plurality of latency control circuits configured to ensure a latency is bounded to a maximum value for a given access to the data array, wherein a given latency control circuit is associated with a corresponding group of the plurality of groups. The latency for a given access may thus vary between a minimum access latency for a group closest to the pipeline control circuit to a maximum latency for an access to the group furthest from the pipeline control circuit.

Variable hit latency cache

Criticality-informed caching policies

A system and method for efficiently handling data selected for eviction in a computing system. In various embodiments, a computing system includes one or more processors, a system memory, and a victim cache. The cache controller of a particular cache in a cache memory subsystem includes an allocator for determining whether to allocate data evicted from the particular cache into the victim cache. The data fetched into the first cache includes data fetched to service miss requests, which includes demand requests and prefetch requests. To determine whether to allocate, the allocator determines whether a usefulness of data fetched into the particular cache exceeds a threshold. If so, the evicted data is stored in the victim cache. If not, the evicted data bypasses the victim cache. Data determined to be accessed by a processor is deemed to be of a higher usefulness.

Victim allocations in shared system cache

A method is provided to operate a computer to interoperate with a portable media player. The method includes processing signals provided from the portable media player to the computer that are indicative of whether an accessory has been connected to the portable media player, to determine whether the accessory has been connected to the portable media player. Based on a determination that the accessory has been connected to the portable media player, physiologic data of a user that was provided to the portable media player from a wireless physiologic data gathering device, is received from the portable media player, into the computer, via the accessory.

Integrated media jukebox and physiologic data handling application

Techniques are disclosed relating to set-associative caches in processors. In one embodiment, an integrated circuit is disclosed that includes a set-associative cache configured to receive a request for a data block stored in one of a plurality of ways within the cache, the request specifying an address, a portion of which is a tag value. In such an embodiment, the integrated circuit includes a way prediction circuit configured to predict, based on the tag value, a way in which the requested data block is stored. The integrated circuit further includes a tag array circuit configured to perform a comparison of a portion of the tag value with a set of previously stored tag portions corresponding to the plurality of ways. The tag array circuit is further configured to determine whether the request hits in the cache based on the predicted way and an output of the comparison.

Cache way prediction

Techniques are disclosed relating to managing data-request dependencies for a cache. In one embodiment, an integrated circuit is disclosed that includes a plurality of requesting agents and a cache. The cache is configured to receive read and write requests from the plurality of requesting agents including a first request and a second request. The cache is configured to detect that the first and second requests specify addresses that correspond to different portions of the same cache line, and to determine whether to delay processing one of the first and second requests based on whether the first and second requests are from the same requesting agent. In some embodiments, the cache is configured to service the first and second requests in parallel in response to determining that the first and second requests are from the same requesting agent.

Cache dependency handling

Growing community of inventors

Aliso Viejo, CA, United States of America

Sandeep Kumar Gupta