International Business Machines Corporation

Aaron Tsai

Christian Jacobi

Chung-Lung K Shum

Martin Recktenwald

Anthony Saporito

Brian David Barrick

Gregory William Alexander

Christian Zoellin

Ulrich Mayer

Brian Robert Prasky

Barry Watson Krumm

Deanna Postles Dunn Berger

Markus Helms

Eyal Naor

Johannes C Reichart

Richard Joseph Branciforte

Timothy John Slegel

James J Bonanno

Timothy Carl Bronson

Michael H Wood

Bradley Nelson

Jennifer A Navarro

James R Mitchell

Yossi Shapira

Eric M Schwarz

Fadi Y Busaba

Charles Franklin Webb

Markus Kaltenbach

Thomas Winters Fox

Mark Anthony Check

Hans-Werner Tast

David S Hutton

John G Rell, Jr

Edward Thomas Malley

Deanna P D Berger

Ashraf ElSharif

Michael T Huffer

Somin Song

Taylor J Pritchard

Dan F Greiner

Michael F Fee

Michael Andrew Blake

Ute Gaertner

Bruce C Giamei

Scott Barnett Swaney

Jonathan T Hsieh

John Robert Ehrman

Thomas G Koehler

Dean G Bair

Rebecca S Wisniewski

Akash V Giri

Richard Esten Bohn

Joshua M Weinberg

Yair Fried

Ching-Farn Eric Wu

Matthias Pflanz

Vimal M Kapadia

Gregory Miaskovsky

Ka-shan Choy

Ka Shan Choy

A lower-level cache managing cross-core invalidation (XI) snapshots in a shared-memory multiprocessing system, wherein the management of XI snapshots reduces an amount of required snapshots while allowing shared lower-level caches, comprising: the lower-level cache maintaining respective response sync state for at least one processor in a plurality of processors signifying that a line may have been changed by another processor since last fetched by a requesting processor.

Cross-core invalidation snapshot management

Disclosed herein is a virtual cache and method in a processor for supporting multiple threads on the same cache line. The processor is configured to support virtual memory and multiple threads. The virtual cache directory includes a plurality of directory entries, each entry is associated with a cache line. Each cache line has a corresponding tag. The tag includes a logical address, an address space identifier, a real address bit indicator, and a per thread validity bit for each thread that accesses the cache line. When a subsequent thread determines that the cache line is valid for that thread the validity bit for that thread is set, while not invalidating any validity bits for other threads.

Translation support for a virtual cache

In an approach, responsibility for reissuing a fetch micro-operation is allocated to a reissue queue subsequent to a cache miss corresponding to a cache and the fetch micro-operation. Responsive to higher level cache returning data to the cache, an issue selection algorithm of the issue queue is overridden to prioritize reissuing the fetch micro-operation.

Load reissuing using an alternate issue queue

A computer system includes a processor core and a memory system in signal communication with the processor core. The memory system includes a first cache and a second cache. The first cache is arranged at a first level of a hierarchy in the memory system and is configured to store a plurality of first-cache entries. The second cache is arranged at a second level of the hierarchy that is lower than the first level, and stores a plurality of second-cache entries. The first cache maintains a directory that contains information for each of the first-cache entries. The second cache maintains a shadow pointer directory (SPD) that includes one or more SPD entries that maps each of the first-cache entries to a corresponding second cache entry at a lower-level cache location.

Shadow pointer directory in an inclusive hierarchical cache

Aspects include using a shadow copy of a level 1 (L1) cache in a cache hierarchy. A method includes maintaining the shadow copy of the L1 cache in the cache hierarchy. The maintaining includes updating the shadow copy of the L1 cache with memory content changes to the L1 cache a number of pipeline cycles after the L1 cache is updated with the memory content changes.

Using a shadow copy of a cache in a cache hierarchy

A method and a system detects a cache line as a potential or confirmed hot cache line based on receiving an intervention of a processor associated with a fetch of the cache line. The method and system include suppressing an action of operations associated with the hot cache line. A related method and system detect an intervention and, in response, communicates an intervention notification to another processor. An alternative method and system detect a hot data object associated with an intervention event of an application. The method and system can suppress actions of operations associated with the hot data object. An alternative method and system can detect and communicate an intervention associated with a data object.

Reducing cache transfer overhead in a system

To facilitate an efficient processing of contended cache lines, a cache controller that is associated with a requestor receives a fetch request for data from the requestor. The fetch request is associated with a cache scope designation. If the data is in a high-level cache (e.g., L1 cache) associated with the requestor, the cache controller returns the requested data to the requestor. If the data is not in the high-level cache or if the data is not within the cache pool identified by the cache scope of search designation, and/or if obtaining the data is contentious, the controller returns a cache miss, undeliverable data, and request done instruction to the requestor. Such scheme allows or permits address contention events when the requestor deems such events are necessary and/or when important. As such, address contention events, performance, latencies, increased executions times, inefficient use of resources, may be diminished.

Cache management using cache scope designation

Embodiments are for special tracking pool enhancement for core L1 address invalidates. An invalidate request is designated to fill an entry in a queue in a local cache of a processor core, the queue including a first allocation associated with processing any type of invalidate request and a second allocation associated with processing an invalidate request not requiring a response in order for a controller to be made available, the entry being in the second allocation. Responsive to designating the invalidate request to fill the entry in the queue in the local cache, a state of the controller that made the invalidate request is changed to available based at least in part on the entry being in the second allocation.

Special tracking pool enhancement for core local cache address invalidates

Disclosed herein is a method for operating access to a cache memory via an effective address comprising a tag field and a cache line index field. The method comprises: splitting the tag field into a first group of bits and a second group of bits. The line index bits and the first group of bits are searched in the set directory. A set identifier is generated indicating the set containing the respective cache line of the effective address. The set identifier, the line index bits and the second group of bits are searched in the validation directory. In response to determining the presence of the cache line in the set based on the second searching, a hit signal is generated.

Cache structure using a logical directory

A method, a computer system, and a computer program product to perform a directory lookup in a first level cache for requested cache line data. A first processor core can detect that the requested cache line data is not found in a plurality of sets of data in the first level cache and detect that existing cache line data stored in a least recently used data set stored in the first level cache is in an exclusive state, wherein the existing cache line data stored in the least recently used data set is to be overwritten by the requested cache line data retrieved from a second level cache. Furthermore, the first processor core can send a request for the requested cache line data and a physical address of the least recently used data set to the second level cache and execute additional instructions based on the first level cache and data retrieved from the second level cache.

Cache management

A simultaneous multithread (SMT) processor having a shared dispatch pipeline includes a first circuit that detects a cache miss thread. A second circuit determines a first cache hierarchy level at which the detected cache miss occurred. A third circuit determines a Next To Complete (NTC) group in the thread and a plurality of additional groups (X) in the thread. The additional groups (X) are dynamically configured based on the detected cache miss. A fourth circuit determines whether any groups in the thread are younger than the determined NTC group and the plurality of additional groups (X), and flushes all the determined younger groups from the cache miss thread.

Cache miss thread balancing

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Poughkeepsie, NY, United States of America

Aaron Tsai