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Swap Faulting and Partial Swap

IP.com Disclosure Number: IPCOM000043236D
Original Publication Date: 1984-Aug-01
Included in the Prior Art Database: 2005-Feb-04

Publishing Venue

IBM

Related People

Authors:
Beretvas, T Buco, WM Greenberg, J Patterson, DR Spivak, GA Tetzlaff, WH [+details]

Abstract

A new concept of "swap-faulting" and "partial swap" is described as part of a virtual machine control program (CP). CP swapping involves a new page-selection mechanism. The new concept results in replacing the large majority of demand paging operations by blocked (swap) paging, i.e., moving multiple pages per start I/O instruction. The new selection relies on the page reference bits being set by a virtual machine in its execution. When the virtual machine finishes its (dispatch) Q-stay, i.e., is Q-dropped, then the working set for this virtual machine is identified. Pages not belonging in the working set are "trimmed"; they are moved onto the flush list, being made available. The working set of the Q-dropped user is broken up into groups of pages, called swapsets.