Browse Prior Art Database

One-Stage Swap-Out with Extended Swap

IP.com Disclosure Number: IPCOM000045122D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Beretvas, T: AUTHOR

Abstract

This article describes a single stags swap out improvement in the extended swap control program described in the preceding article. Extended swap writes out an entire swap-in set, i.e., all the referenced pages (changed or unchanged), and LSQA (local system queue area) pages to swap datasets, so that at swap-in time the entire swapin set can be read from the swap datasets on DASD as an entity (or more precisely, several swapset entities) in a single-stage operation.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 82% of the total text.

Page 1 of 1

One-Stage Swap-Out with Extended Swap

This article describes a single stags swap out improvement in the extended swap control program described in the preceding article. Extended swap writes out an entire swap-in set, i.e., all the referenced pages (changed or unchanged), and LSQA (local system queue area) pages to swap datasets, so that at swap-in time the entire swapin set can be read from the swap datasets on DASD as an entity (or more precisely, several swapset entities) in a single-stage operation.

Changed unreferenced pages are trimmed from the working set at swap-out time, and they are written onto the local page datasets. The swap-out process is therefore still a twostage process: the trimmed changed pages are written to local page datasets, and upon completion of these operations the swap-in set is written to swap datasets. The swap-in process is a one-stage process, the swap-in set is retrieved from the swap datasets. The LSQA pages are not used anymore to record the location of the non-LSQA pages written to the swap datasets.

Both extended swap-out and swap-in processes are illustrated in the preceding article.

The one-stage swap-out process can improve system performance in a system with the extended swap routine. This means that the writing of trimmed changed pages to local page datasets should begin con currently with the writing of the swap-in set to swap datasets. In as much as the datasets are distinct, and there is no dependency between the writ...