ACCESSING REMOTE MEMORY ON A MEMORY BLADE

• US 20140068209A1
• Filed: 08/28/2012
• Published: 03/06/2014
• Est. Priority Date: 08/28/2012
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Inventors: Muralimanohar, Naveen, Jouppi, Norman Paul, Schreiber, Robert, Lim, Kevin T.
• Granted Patent: US 9,164,904 B2
• Time in Patent Office: Days
• US Class Current: 711/162
• CPC Class Codes: G06F 12/08 in hierarchically structured memory systems, e.g. virtual memory systems
• CPC Class Codes: G06F 2212/254 Distributed memory
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A method of accessing remote memory comprising receiving a request for access to a page from a computing device, adding an address of the accessed page to a recent list memory on the remote memory, associating a recent list group identifier to a number of addresses of accessed pages, transferring the requested page to the computing device with the recent list group identifier and temporarily maintaining a copy of the transferred page on the remote memory.

Claims

1. A method of accessing remote memory comprising:

receiving a request for access to a page from a computing device;

adding an address of the accessed page to a recent list memory on the remote memory;

associating a recent list group identifier to a number of addresses of accessed pages;

transferring the requested page to the computing device with the recent list group identifier and temporarily maintaining a copy of the transferred page on the remote memory.

2. The method of claim 1, in which the recent list memory comprises a number of addresses associated with pages that have been requested by the computing device, those addresses being organized into logical groups, and in which the remote memory frees a number of pages associated with a number of addresses on the recent list memory, which comprise a single group.

3. The method of claim 2, in which the pages associated with a number of addresses on the recent list memory are freed after a predetermined amount of time, after a number of addresses have accumulated in the recent list memory, or combinations thereof.

4. The method of claim 1, in which the recent list group identifier of a page evicted from the computing device is compared to a newest freed recent list group identifier associated with a group of pages most recently freed on the remote memory,

in which if the recent list group identifier of the evicted page is newer than the newest freed recent list group identifier, then the computing device:

sends the address of recent list group identifier of the page to be evicted to the remote memory; and

causes the address of the page to be evicted to the remote memory stored on the recent list memory to be freed and the page associated with the address to be made available again.

5. The method of claim 1, in which receiving an evicted page from the local memory further comprises receiving page modification metadata indicating which bits of data within the page being evicted had been changed while the page was on the computing device.

6. The method of claim 5, in which the remote memory uses the page modification metadata to change the indicated portions of the page such that the changes made to the page while the page was on the computing device are reflected in the copy of the transferred page.

7. The method of claim 5, in which the page modification metadata comprises encoded data comprising information regarding the changed blocks of data, concatenated consecutively, together with a bit vector having a length of (page_length)/(line_length) equal to the number of lines per page.

8. The method of claim 1, in which changes to the transferred page while the transferred page is located on the computing device are periodically copied to the maintained copy of the transferred page on the remote memory.

9. A computing device comprising:

a compute blade maintaining local memory;

a memory blade maintaining remote memory and communicatively coupled to the compute blade;

a processor to request, transfer, and evict pages of memory to and from the local and remote memory; and

a recent list memory to store a number of addresses associated with pages of data requested by the compute blade.

10. The computing device of claim 9, further comprising a free pool in which a number of pages of data associated with the number of addresses within the recent list memory are freed after a predetermined amount of time, after a number of addresses have accumulated in the recent list memory, or combinations thereof.

11. The computing device of claim 9, in which changes to any transferred page while the transferred page is located on the compute blade are periodically copied to a temporarily maintained copy of the transferred page on the memory blade.

12. The computing device of claim 9, in which, upon transfer of a remote page to the compute blade, the memory blade further provides the compute blade with an identifier associated with the transferred remote page as well as the address of the remote page.

13. The computing device of claim 12, in which the compute blade provides page modification metadata to the memory blade upon eviction of the remote page from the compute blade and in which the page modification metadata defines which bits of data within the page being evicted had been changed while the page was on the compute blade.

14. The computing device of claim 13, in which the memory blade receives a signal from the compute blade that the page is being evicted and, using the page modification metadata, amends a copy of the evicted page temporarily maintained on the memory blade before releasing that copy.

15. A computer program product comprising:

a computer readable storage medium having computer usable program code embodied therewith, the computer usable program code comprising;

computer usable program code to, when executed by the processor, receive a request for access to a page from a computing device;

computer usable program code to, when executed by the processor, add an address of the accessed page to a recent list memory on remote memory;

computer usable program code to, when executed by the processor, associate a recent list group identifier to a number of addresses of accessed pages;

computer usable program code to, when executed by the processor, receive an evicted page from the local memory on the computing device;

computer usable program code that, when executed by the processor, transfer the requested page to the computing device with the recent list group identifier

computer usable program code to, when executed by the processor, choose a page to evict from local memory;

computer usable program code to, when executed by the processor, determine if the page to be evicted originated from remote memory;

computer usable program code to, when executed by the processor, compare the value of the recent list group identifier to the newest freed recent list group identifier on the remote memory;

computer usable program code to, when executed by the processor, determine if the value of recent list group identifier is newer than the newest freed recent list group identifier;

computer usable program code to, when executed by the processor, send the address and recent list group identifier associated with the page to be evicted to the remote memory; and

computer usable program code to, when executed by the processor, cause a copy of the local page being evicted and which is located on the remote memory to be freed.