Browse Prior Art Database

Method for Quick Recording of Change and Tag Change Bit in Hashed Page Table

IP.com Disclosure Number: IPCOM000104281D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 1 page(s) / 49K

Publishing Venue

IBM

Related People

Brown, JD: AUTHOR [+2]

Abstract

Disclosed is a method that allows setting the Change bit in the system architecture inside a Page Table Entry in one store. The previous method was to fetch each Page Table Entry in the Page Table Group until the correct Page Table Entry (PTE) was found, then set the bit in that proper Page Table Entry.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 60% of the total text.

Method for Quick Recording of Change and Tag Change Bit in Hashed Page Table

      Disclosed is a method that allows setting the Change bit in the
system architecture inside a Page Table Entry in one store.  The
previous method was to fetch each Page Table Entry in the Page Table
Group until the correct Page Table Entry (PTE) was found, then set
the bit in that proper Page Table Entry.

      When the first store has occurred into a virtual page, it is
necessary to update the hashed page table entry for that page in
order to record the fact that the page has been changed.  (The first
time a tag within the page is written to '1' also needs to be
recorded.)  In order to accomplish this, it is necessary to locate
the appropriate entry in the Hash Page Table (HPT) which can be very
large.  The architecture defines a means for searching the HPT for a
particular page.

      This disclosure describes a means to provide this update
capability without requiring the Hashed Page Table be searched to
find the correct entry.  The invention takes advantage of the fact
that, when the first access to a page occurs, the target address will
not be translatable through the Translate Look-aside Buffer (TLB).
This will initiate a search of the HPT and the resulting information
needed to allow immediate translation will be stored into the TLB.

      The essential nature of this disclosure is that, in addition to
the information needed to translate the address, we store inf...