Browse Prior Art Database

Page Reference Monitor for OSF/1 Systems

IP.com Disclosure Number: IPCOM000110688D
Original Publication Date: 1992-Dec-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 1 page(s) / 60K

Publishing Venue

IBM

Related People

Fortin, MR: AUTHOR

Abstract

Disclosed is a monitor that provides a page-reference by page-reference trace for processes running on an OSF/1* system. Every pageable page referenced by processes on the system is observable by the technique employed by the monitor. On machines running the OSF/1 Operating System, the pmap, or physical map, interface comprises a set of services that manage the address translation hardware of the machine. The pmap is not required to maintain address translations for all addresses because all required virtual-physical translations are kept within a separate and machine-independent system. However, an address cannot be accessed if there is no pmap entry for the page containing the address.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 56% of the total text.

Page Reference Monitor for OSF/1 Systems

       Disclosed is a monitor that provides a page-reference by
page-reference trace for processes running on an OSF/1* system.
Every pageable page referenced by processes on the system is
observable by the technique employed by the monitor.  On machines
running the OSF/1 Operating System, the pmap, or physical map,
interface comprises a set of services that manage the address
translation hardware of the machine.  The pmap is not required to
maintain address translations for all addresses because all required
virtual-physical translations are kept within a separate and
machine-independent system.  However, an address cannot be accessed
if there is no pmap entry for the page containing the address.

      When an address is requested and the address is not contained
within the pmap, the system incurs a fault on the page containing the
address.  If the page containing the address is not resident in RAM,
the fault is handled by first retrieving the page from secondary
storage and then by creating a pmap entry for the page.  If the page
is memory resident, then all that is required to resolve the fault is
the construction of a pmap entry for the page.  After the creation of
the pmap entry, the address is accessible by the system.

      The Page Reference Monitor operates by first invalidating all
pmap entries to pageable pages.  (A pageable page is one that can
incur a fault.  Pages which cannot incur a fault are no...