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Task Dispatching Using a Shadow Directory

IP.com Disclosure Number: IPCOM000043925D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05

Publishing Venue

IBM

Related People

Authors:
Hoevel, LW Liu, L Pomerene, J Puzak, TR Rechtschaffen, RN Rosenfeld, P Sparacio, F Voldman, F [+details]

Abstract

To reduce the finite cache penalty it is proposed to make the task dispatching decisions of the operating system sensitive to the current cache contents (L1 and L2) and to dispatch that task which is most likely to use the current cache contents most efficiently. Given a set of putative starting addresses derived from TCB OLDPSW (Task Control Block Old Program Status Word), it is possible to determine which of these addresses has the longest sequence of cache resident lines by chaining successively through the first and second level entries of the shadow directory and by testing second level entries against the L1 directory to determine if they are resident therein. First level entries can be assumed to be resident in the L2 cache.