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Deterministic Context Switching of Registers

IP.com Disclosure Number: IPCOM000037054D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29

Publishing Venue

IBM

Related People

Authors:
Beetcher, RC Corrigan, MJ Funk, MR Jackson, DT Roediger, RR [+details]

Abstract

Described are mechanisms which determine whether floating-point registers need to be saved/restored on each context switch. A significant portion of a processing unit's cycles are used during context switching, and a significant portion of this time is spent in the process of saving and restoring processor registers into and out of main storage. On many processors, a portion of this register space is used to contain floating-point data. If these floating-point registers are not loaded or modified from one context switch to the next, it is not necessary to save the floating-point registers. If the task or procedure which is being switched into the processor had not previously required the use of floating-point registers, the floating-point registers do not need to be restored.