International Business Machines Corporation

Taylor J Pritchard

Gregory William Alexander

Aaron Tsai

Deanna Postles Dunn Berger

Jonathan T Hsieh

Michael J Cadigan, Jr

Richard Joseph Branciforte

Ashraf ElSharif

Christian Jacobi

Michael F Fee

Markus Kaltenbach

Michael Andrew Blake

Timothy Carl Bronson

Jane Helen Bartik

Yossi Shapira

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

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

Systems and methods of performing processor pipeline management include receiving an instruction for processing, determining that data in a first memory sub-group of a memory group needed to process the instruction is not available in a cache that ensures fixed latency access, and determining that the instruction should be put in a sleep state. The sleep state indicates that the instruction will not be reissued until the instruction is moved to a wakeup state. The methods also include associating the instruction with a ticket identifier (ID) that corresponds with a second memory sub-group of the memory group, and moving the instruction to the wakeup state based on the second memory sub-group of the memory group being moved into the cache.

Processor pipeline management during cache misses using next-best ticket identifier for sleep and wakeup

Embodiments of the inventions are directed towards a computer-implemented methods and systems for determining an oldest logical memory address. The method includes creating an M number of miss request registers and an N number of stations in a load/store unit of the processor. In response to load requests from target instructions, a processor detects each L1 cache miss. The processor stores data related to each L1 cache miss in a respective miss request register. The data includes an age of each L1 cache miss and a portion of a logical memory address of the requested load. The processor stores the entire logical memory addresses of the requested loads in respective stations based on an age of the load requests. The processor transmits the oldest logical memory address that is stored at the stations.

Determining logical address of an oldest memory access request

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Poughkeepsie, NY, United States of America

Taylor J Pritchard