OpenSolaris

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Bug ID 6567390
Synopsis clock efficiency optimizations ('tickless' clock)
State 3-Accepted (Yes, that is a problem)
Category:Subcategory kernel:time
Keywords sfo | tesla | xen
Responsible Engineer Eric Saxe
Reported Against e_001
Duplicate Of
Introduced In
Commit to Fix
Fixed In
Release Fixed
Related Bugs 6549669
Submit Date 8-June-2007
Last Update Date 13-June-2007
Description
clock() fires (by default) 100 times a second, performing various accounting tasks, tick processing (for all other CPUs in the system), and callout/timeout execution.

There are many times when clock fires, and there's really nothing significant to do (especially on otherwise idle systems)...but nevertheless it must wake up at a regular interval only to discover this. Where the CPU would otherwise remain in a reduced power state (since it is otherwise idle), this costs in terms of power efficiency, and in the case of a laptop, battery life.

This RFE seeks to provide a "tickless" implementation for clock, so that rather than blindly waking up 100 times a second to potentially perform a variety of tasks, we can let the CPU slumber off until such time as we know a timeout/callout event is due, accounting can be performed more lazily, and tick processing would only be performed when certain CPUs are non-idle, etc.
Work Around
N/A
Comments
N/A