Messages in this thread |  | | Date | Fri, 25 Aug 2006 14:54:52 +1000 | | From | Nick Piggin <> | | Subject | Re: [RFC] maximum latency tracking infrastructure |
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Arjan van de Ven wrote: > Jesse Barnes wrote: > >> On Thursday, August 24, 2006 10:41 am, Arjan van de Ven wrote: >> >>> The reason for adding this infrastructure is that power management in >>> the idle loop needs to make a tradeoff between latency and power >>> savings (deeper power save modes have a longer latency to running code >>> again). >> >> >> What if a processor was already in a sleep state when a call to >> set_acceptable_latency() latency occurs? > > > there's nothing sane that can be done in that case; any wake up already > will cause the unwanted latency! > A premature wakeup is only making it happen *now*, but now is as > inconvenient a time as any... > (in fact it may be a worst case time scenario, say, an audio interrupt...)
Surely you would call set_acceptable_latency() *before* running such operation that requires the given latency? And that set_acceptable_latency would block the caller until all CPUs are set to wake within this latency.
That would be the API semantics I would expect, anyway.
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