Apparatus and method to preserve data in a set associative memory device

• US 5,584,014 A
• Filed: 12/20/1994
• Issued: 12/10/1996
• Est. Priority Date: 12/20/1994
• Status: Expired due to Term

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Nayfeh, Basem A., Khalidi, Yousef A.
• Primary Examiner(s): Robertson, David L.
• Application Number:
  US08/359,403
• Time in Patent Office: 721 Days
• Field of Search: 395/460, 395/471, 395/472, 395/486, 395/461
• US Class Current: 711/134
• CPC Class Codes: G06F 12/126 with special data handling, e.g. priority of data or instructions, handling errors or pinning

Abstract

An apparatus and method to dynamically partition a set-associative memory device is described. The apparatus includes a set identification device to specify a group of set-associative data blocks in a cache memory or translation-lookaside buffer. A block replacement logic circuit is used to identify replaceable blocks within the set-associative data blocks that can store new information. The block replacement logic circuit is also used to identify un-replaceable blocks within the set-associative data blocks that cannot store new information. The block replacement logic circuit only writes new information to the replaceable blocks of the set-associative data blocks. The block replacement logic circuit can be implemented using a block replacement mask to identify within the set-associative data blocks the replaceable blocks and the un-replaceable blocks.

Claims

1. A method of storing information in a computer memory, said method comprising the steps of:

specifying a set of k data blocks;

using block replacement logic to identify whether a selected data block of said set of k data blocks is replaceable;

checking a block replacement mask containing k bits corresponding to said k data blocks to identify whether said selected data block is unlocked; and

writing new information to said selected data block only if said block replacement mask indicates that said selected data block is unlocked.

2. The method of claim 1 wherein said specifying step includes the step of specifying a set of data blocks in a cache memory.

3. The method of claim 1 wherein said specifying step includes the step of specifying a set of data blocks in a translation-lookaside buffer.

4. An apparatus to store information in a computer memory, said apparatus comprising:

a set identification device to specify a set of k data blocks;

a block replacement mask containing k bits, each bit specifying whether a selected data block of said set k data blocks is replaceable; and

a block replacement logic circuit to identify from said block replacement mask a replaceable data block of said set of k data blocks, and write new information to said replaceable data block.

5. The apparatus of claim 4 wherein said set identification device specifies a set of data blocks in a cache memory.

6. The apparatus of claim 4 wherein said set identification device specifies a set of data blocks in a translation-lookaside buffer.

7. A method of constructing an apparatus to store information in a computer memory, said method comprising the steps of:

providing a set identification device to specify a set of k data blocks;

providing a block replacement mask containing k bits, each bit specifying whether a selected data block of said set k data blocks is replaceable; and

providing a block replacement logic circuit to identify from said block replacement mask a replaceable data block of said set of k data blocks, and write new information to said replaceable data block.

8. The method of claim 7 further comprising the step of identifying a set of data blocks in a cache memory.

9. The method of claim 7 further comprising the step of identifying a set of data blocks in a translation-lookaside buffer.