Browse Prior Art Database

Control Section/System Queue Area Interspersion

IP.com Disclosure Number: IPCOM000079999D
Original Publication Date: 1973-Oct-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Brannon, TL: AUTHOR

Abstract

In a virtual storage operating system having a control program nucleus with pageable control sections (CSECTs), paging of the nucleus is minimized by locating the pageable CSECTs so as not to cross page boundaries. As a result, some unused gaps are left on those pages. Fig. 1 is the flow diagram for a method of using that space as pageable system queue area (PSQA).

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Control Section/System Queue Area Interspersion

In a virtual storage operating system having a control program nucleus with pageable control sections (CSECTs), paging of the nucleus is minimized by locating the pageable CSECTs so as not to cross page boundaries. As a result, some unused gaps are left on those pages. Fig. 1 is the flow diagram for a method of using that space as pageable system queue area (PSQA).

Pageable nucleus CSECTs are assigned to the high end of the highest available virtual page. NO CSECT smaller than a page is allowed to overlap a page boundary. If this results in an unused area at the bottom of the page, its size is calculated. Then a free queue element (FQE) is built at the beginning of the area to describe it as free PSQA. The FQE consists of a four-byte pointer to the next FQE and a length field for the size of the free area. This continues until all pageable nucleus CSECTs are processed and the PSQA is chained together. Fig. 2 shows the arrangement of high-virtual storage as a result of the CSECT/PSQA interspersion. Finally, the interspersed PSQA is chained to a large contiguous area defined as the "main" PSQA.

As shown in Fig. 2, the PSQA is chained from low to high, causing the "main" PSQA to be used first. When the interspersed PSQA is needed, its use will avert or at least delay an out-of-storage situation for PSQA.

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