Method and system for providing an eviction protocol within a non-uniform memory access system

• US 6,266,743 B1
• Filed: 02/26/1999
• Issued: 07/24/2001
• Est. Priority Date: 02/26/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Dean, Mark Edward, Carpenter, Gary Dale, Glasco, David Brian
• Primary Examiner(s): Yoo, Do Hyun
• Assistant Examiner(s): PHAM, VU A
• Application Number:
  US09/259,365
• Time in Patent Office: 879 Days
• Field of Search: 711/143, 711/141, 711/122, 711/145, 711/155, 712/28
• US Class Current: 711/143
• CPC Class Codes: G06F 12/082 Associative directories G06F12/0822 takes precedence
• CPC Class Codes: G06F 12/12 Replacement control

Abstract

A method and system for providing an eviction protocol within a non-uniform memory access (NUMA) computer system are disclosed. A NUMA computer system includes at least two nodes coupled to an interconnect. Each of the two nodes includes a local system memory. In response to a request for evicting an entry from a sparse directory, an non-intervention writeback request is sent to a node having the modified cache line when the entry is associated with a modified cache line. After the data from the modified cache line has been written back to a local system memory of the node, the entry can then be evicted from the sparse directory. If the entry is associated with a shared line, an invalidation request is sent to all nodes that the directory entry indicates may hold a copy of the line. Once all invalidations have been acknowledged, the entry can be evicted from the sparse directory.

Claims

1. A method for providing an eviction protocol for a sparse directory within a non-uniform memory access (NUMA) computer system, wherein said NUMA computer system includes at least two nodes coupled to an interconnect, each of said at least two nodes includes a local system memory, said method comprising the steps of:

in response to a request for evicting an entry from a sparse directory, wherein said entry is associated with a modified cache line, sending an non-intervention writeback request from a home node of said modified cache line to a remote node having said modified cache line;

initiating a second writeback request from said remote node to write back said modified cache line to said home node while retrying said non-intervention writeback request at said remote node; and

evicting said entry from said sparse directory after said non-intervention writeback request at said remote node has been completed.

2. The method according to claim 1, wherein said non-intervention writeback request is an non-intervention writeback with AutoRetry.

3. The method according to claim 1, wherein said non-intervention writeback request is an non-intervention read-with-intent-to-modify transaction.

4. The method according to claim 1, wherein said second writeback request is a write-back-kill request.

5. The method according to claim 1, wherein said non-intervention writeback request is completed with a clean response.

6. The method according to claim 1, wherein said evicting step is initiated by said remote node after said non-intervention writeback request at said remote node has been completed.

7. The method according to claim 1, wherein said entry in said sparse directory indicates said modified cache line is shared by said home node and said remote node.

8. A non-uniform memory access (NUMA) computer system capable of providing an eviction protocol for a sparse directory, wherein said NUMA computer system includes at least two nodes coupled to an interconnect, each of said at least two nodes includes a local system memory, said NUMA computer system comprising:

means for sending an non-intervention writeback request from a home node of a modified cache line to a remote node having said modified cache line, in response to a request for evicting an entry from a sparse directory, wherein said entry is associated with said modified cache line;

means for initiating a second writeback request from said remote node to write back said modified cache line to said home node while retrying said non-intervention writeback request at said remote node; and

means for evicting said entry from said sparse directory after said non-intervention writeback request at said remote node has been completed.

9. The NUMA computer system according to claim 8, wherein said non-intervention writeback request is an non-intervention writeback with AutoRetry.

10. The NUMA computer system according to claim 8, wherein said non-intervention writeback request is an non-intervention read-with-intent-to-modify transaction.

11. The NUMA computer system according to claim 8, wherein said second writeback request is a write-back-kill request.

12. The NUMA computer system according to claim 8, wherein said non-intervention writeback request is completed with a clean response.

13. The NUMA computer system according to claim 8, wherein said evicting means is initiated by said remote node after said non-intervention writeback request at said remote node has been completed.

14. The NUMA computer system according to claim 8, wherein said entry in said sparse directory indicates said modified cache line is shared by said home node and said remote node.