Adaptive page placement memory management system

• US 5,394,537 A
• Filed: 10/01/1993
• Issued: 02/28/1995
• Est. Priority Date: 12/13/1989
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Oxley, Donald W., Courts, Howard R.
• Primary Examiner(s): Dixon, Joseph L.
• Assistant Examiner(s): Nguyen, Hiep T.
• Application Number:
  US08/131,107
• Time in Patent Office: 515 Days
• Field of Search: 364/200 MS File, 364/900 MS File, 395/400, 395/425
• US Class Current: 711/202
• CPC Class Codes: G06F 12/08 in hierarchically structured memory systems, e.g. virtual memory systems
• CPC Class Codes: G06F 12/121 using replacement algorithms

Abstract

A virtual memory system groups pages into clusters according to use, determined by first reference and frequency of reference. The virtual memory system comprises a random access memory and an auxiliary memory. A central processing unit the virtual memory system with an address. Whenever that address identifies a memory location not stored in the RAM, the entire cluster of pages in which the address is located is retrieved from the auxiliary memory into the random access memory.

Claims

1. A memory system, comprising:

a central processor;

an address translator coupled to said central processor;

a main memory coupled to said translator;

an auxiliary memory coupled to said translator; and

a memory manager for selecting pages of data on the basis of frequent reference by said processor, independent of page location on a virtual address space, and transferring said selected pages in groups from said main memory to contiguous regions of said auxiliary memory.

2. The memory system of claim 1, wherein said pages are selected for preemption on the basis of their order of first reference and subsequent frequency of reference by said processor.

3. The memory system of claim 1, wherein each group is a cluster comprising at least one page and a cluster header containing the status and location information for each page contained within the cluster.

4. The memory system of claim 3, wherein the data forming one of said clusters which is transferred to said auxiliary memory in a single transfer will be transferred to said main memory in a single transfer.

5. A method of memory management in a memory system, comprising the steps of:

selecting pages in a main memory based upon their order of first reference and subsequent frequency of reference by a processor;

grouping a predetermined number of frequently selected pages into a cluster;

transferring said cluster to a contiguous region of an auxiliary memory; and

transferring said cluster from said contiguous region of said auxiliary memory to said main memory responsive to reference, by said processor, to one of said selected pages in said cluster.

6. The method of claim 5, wherein said first reference refers to the instance when a page is first referenced by the processor, subsequent to its fault into main memory.

7. The method of claim 5, further including time of last reference of said pages as a factor in selecting said pages in said main memory.