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Browse Prior Art Database

Hardware Frame Reference Counts

IP.com Disclosure Number: IPCOM000116457D
Original Publication Date: 1995-Sep-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Greenstein, PG: AUTHOR [+3]

Abstract

Disclosed is a method for computer processor hardware to count references to frames of storage by a software program executing on the processor, and to report the results to the operating system. The frames of storage may contain pages of computer memory.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 53% of the total text.

Hardware Frame Reference Counts

      Disclosed is a method for computer processor hardware to count
references to frames of storage by a software program executing on
the processor, and to report the results to the operating system.
The frames of storage may contain pages of computer memory.

      Define a hardware frame reference count array, containing one
entry per frame.  For the purposes of this disclosure, assume that
each array entry has 8 bits.  Each array entry is a counter, starting
at 0 and never wrapping or overflowing (i.e., when the counter value
reaches 'FF'X, it stays that way until cleared by the operating
system).  For each frame, the corresponding counter array entry will
be incremented by hardware to reflect the number of references.

Note: Another option is to extend the existing storage key array to
include the counters, and use a modified set of storage key
management commands.

      Operating system can reference and update the counters via a
new instruction -- Update Reference Count (URC).  The instruction
will have two operand fields:
  1.  The frame identifier operand.
        This field identifies the frame for which the counter value
       is to be returned and the counter is to be reset.  If this is
       the first time the instruction is issued for this frame since
       Initial Program Load (IPL), the hardware will allocate the
       array entry counter, set the counter to zero, and retu...