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Browse Prior Art Database

Working Set Determination

IP.com Disclosure Number: IPCOM000041634D
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Beretvas, T: AUTHOR [+6]

Abstract

Disclosed is a technique included in an operating system to determine the working set of interactive users in such fashion that the working set is close to the "theoretical working set", i.e., those pages that are actually referenced in a "very small" interval. More specifically, the interval is to be selected in such a way that if interactive transactions are sorted by length, then 80-90 percent of such transactions actually completes in the interval selected. Further, the working set determined should not be affected by system load or interactions. If the working set is determined in such fashion, then spurious paging (due to a working set identified as too small) is avoided, and interactive user response time improves.

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Working Set Determination

Disclosed is a technique included in an operating system to determine the working set of interactive users in such fashion that the working set is close to the "theoretical working set", i.e., those pages that are actually referenced in a "very small" interval. More specifically, the interval is to be selected in such a way that if interactive transactions are sorted by length, then 80-90 percent of such transactions actually completes in the interval selected. Further, the working set determined should not be affected by system load or interactions. If the working set is determined in such fashion, then spurious paging (due to a working set identified as too small) is avoided, and interactive user response time improves. The new technique replaces a scan of a table in memory of page frame replenishment with replenishment by non-working set pages. Once the true working set of a user (virtual machine) is identified, the other pages that are owned by the virtual machine are assumed to be of lesser value and become the pages given to the replenishment process. Reference bit resets occur only when a user is dropped from a queue (Q-drop). Therefore, the determination of a working set by examining the Reference bits is valid, since there is no contamination by the table scan process. The Q-drop interval is determined essentially by the number of instructions executed. This number is defined in such way that the large majority of transactions (...