Method and system for coordinating baseline and secondary prefetchers

Patent metadata

Field	Value
Publication number	US-10678692-B2
Application number	US-201715709285-A
Country	US
Kind code	B2
Filing date	Sep 19, 2017
Priority date	Sep 19, 2017
Publication date	Jun 9, 2020
Grant date	Jun 9, 2020

Abstract

In one embodiment, a processor comprises a first prefetcher to generate prefetch requests to prefetch data into a mid-level cache; a second prefetcher to generate prefetch requests to prefetch data into the mid-level cache; and a prefetcher selector to select a prefetcher configuration for the first prefetcher and the second prefetcher based on at least one memory access metric, wherein the prefetcher configuration is to specify whether the first prefetcher is to be enabled to issue, to the mid-level cache, prefetch requests for data of a particular page and whether the second prefetcher is to be enabled to issue, to the mid-level cache, prefetch requests for data of the particular page.

First claim

What is claimed is:

1. A processor comprising:
a first prefetcher comprising circuitry, the first prefetcher configured to generate prefetch requests to prefetch data into a mid-level cache; a second prefetcher comprising circuitry,
the second prefetcher configured to generate prefetch requests to prefetch data into the mid-level cache;
a prefetcher selector to select a prefetcher configuration for the first prefetcher and the second prefetcher based on at least one memory access metric, wherein the prefetcher configuration is to specify whether the first prefetcher is enabled to issue, to the mid-level cache, prefetch requests for data of a particular page and whether the second prefetcher is enabled to issue, to the mid-level cache, prefetch requests for data of the particular page, wherein the selected prefetcher configuration is to specify that the first prefetcher is enabled to issue, to the mid-level cache, prefetch requests for data of the particular page and the second prefetcher is not enabled to issue, to the mid-level cache, prefetch requests for data of the particular page; and

wherein the prefetcher configuration is modifiable by the prefetcher selector to specify that the first prefetcher is not enabled to issue, to the mid-level cache, prefetch requests for data of the particular page and the second prefetcher is not enabled to issue, to the mid-level cache, prefetch requests for data of the particular page.

2. The processor of claim 1 , wherein the prefetcher configuration is selected from a first configuration to specify that the first prefetcher is enabled to issue, to the mid-level cache, prefetch requests for data of the particular page and the second prefetcher is not enabled to issue, to the mid-level cache, prefetch requests for data of the particular page, a second configuration to specify that the first prefetcher is not enabled to issue, to the mid-level cache, prefetch data of the particular page and the second prefetcher is enabled to issue, to the mid-level cache, prefetch requests for data of the particular page, and a third configuration to specify that the first prefetcher is not enabled to issue, to the mid-level cache, prefetch requests for data of the particular page and the second prefetcher is not enabled to issue, to the mid-level cache, prefetch requests for data of the particular page.

3. The processor of claim 1 , wherein the prefetcher configuration is modified by the prefetcher selector to specify that the first prefetcher is not enabled to issue, to the mid-level cache, prefetch requests for data of the particular page and the second prefetcher is enabled to issue, to the mid-level cache, prefetch requests for data of the particular page.

4. The processor of claim 1 , wherein the prefetcher selector is further to select a second prefetcher configuration for the first prefetcher and the second prefetcher, wherein the second prefetcher configuration is to specify whether the first prefetcher is enabled to issue, to the mid-level cache, prefetch requests for data of a second page and whether the second prefetcher is enabled to issue, to the mid-level cache, prefetch requests for data of the second page, and wherein the prefetcher configuration and the second prefetcher configuration are to be concurrently applied to the first prefetcher and the second prefetcher.

5. The processor of claim 1 , wherein the at least one memory access metric comprises a number of times that data of the particular page has been requested.

6. The processor of claim 1 , wherein the at least one memory access metric comprises a number of times that the second prefetcher has generated accurate prefetch requests for data of the particular page.

7. The processor of claim 1 , wherein the at least one memory access metric comprises a metric based upon a number of times that data of a plurality of pages has been requested.

8. The processor of claim 1 , wherein the at least one memory access metric comprises a metric based upon a number of times that the second prefetcher has generated accurate prefetch requests for data of a plurality of pages.

9. The processor of claim 1 , wherein the prefetcher selector is to select the prefetcher configuration as an initial prefetcher configuration for the particular page based on requests made for data of a plurality of other pages and to change the prefetcher configuration based on requests made for data of the particular page.

10. The processor of claim 1 , wherein data identified by the prefetch requests generated by the first prefetcher and the second prefetcher comprises instructions to be executed by a core of the processor.

11. The processor of claim 1 , wherein data identified by the prefetch requests generated by the first prefetcher and the second prefetcher comprises data operands to be used during execution of instructions by a core of the processor.

12. A method comprising:
generating, by a first prefetcher, prefetch requests to prefetch data into a mid-level cache;
generating, by a second prefetcher, prefetch requests to prefetch data into the mid-level cache;
selecting, by a prefetcher selector, a prefetcher configuration for the first prefetcher and the second prefetcher based on at least one memory access metric, wherein the prefetcher configuration is to specify whether the first prefetcher is enabled to issue, to the mid-level cache, prefetch requests for data of a particular page and whether the second prefetcher is to be enabled to issue, to the mid-level cache, prefetch requests for data of the particular page, wherein the selected prefetcher configuration is to specify that the first prefetcher is enabled to issue, to the mid-level cache, prefetch requests for data of the particular page and the second prefetcher is not enabled to issue, to the mid-level cache, prefetch requests for data of the particular page; and
modifying, by the prefetcher selector, the prefetcher configuration to specify that the first prefetcher is not enabled to issue, to the mid-level cache, prefetch requests for data of the particular page and the second prefetcher is not enabled to issue, to the mid-level cache, prefetch requests for data of the particular page.

13. The method of claim 12 , wherein the at least one memory access metric comprises a number of times that data of the particular page has been requested.

14. The method of claim 12 , wherein the at least one memory access metric comprises a number of times that the second prefetcher has generated accurate prefetch requests for data of the particular page.

15. The method of claim 12 , wherein the at least one memory access metric comprises a metric based upon a number of times that data of a plurality of pages has been requested.

16. A system comprising: a system memory; and a processor comprising: a mid-level cache;
a first prefetcher configured to generate prefetch requests to prefetch data from the system memory into the mid-level cache;
a second prefetcher configured to generate prefetch requests to prefetch data from the system memory into the mid-level cache;
a prefetcher selector to select a prefetcher configuration for the first prefetcher and the second prefetcher based on at least one memory access metric, wherein the prefetcher configuration is to specify whether the first prefetcher is enabled to issue, to the mid-level cache, prefetch requests for data of a particular page and whether the second prefetcher is enabled to issue, to the mid-level cache, prefetch requests for data of the particular page, wherein the selected prefetcher configuration k to specify that the first prefetch

Assignees

• Intel Corp

Inventors

• Pugsley Seth H
• Shevgoor Manjunath
• Wilkerson Christopher B

Classifications

• G06F12/0806

  Multiuser, multiprocessor or multiprocessing cache systems · CPC title

• G06F2212/602

  Details relating to cache prefetching · CPC title

• G06F12/0862 Primary

  with prefetch · CPC title

• G06F9/30047

  Prefetch instructions; cache control instructions · CPC title

• G06F12/0897

  with two or more cache hierarchy levels (with multilevel cache hierarchies G06F12/0811) · CPC title