Messages in this thread |  | | Date | Wed, 05 Nov 2014 22:41:00 +0100 | From | Daniel Lezcano <> | Subject | Re: [PATCH V2 1/5] sched: idle: cpuidle: Check the latency req before idle |
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On 11/05/2014 10:57 PM, Rafael J. Wysocki wrote: > On Thursday, October 23, 2014 11:01:17 AM Daniel Lezcano wrote: >> When the pmqos latency requirement is set to zero that means "poll in all the >> cases". >> >> That is correctly implemented on x86 but not on the other archs. >> >> As how is written the code, if the latency request is zero, the governor will >> return zero, so corresponding, for x86, to the poll function, but for the >> others arch the default idle function. For example, on ARM this is wait-for- >> interrupt with a latency of '1', so violating the constraint. >> >> In order to fix that, do the latency requirement check *before* calling the >> cpuidle framework in order to jump to the poll function without entering >> cpuidle. That has several benefits: >> >> 1. It clarifies and unifies the code >> 2. It fixes x86 vs other archs behavior >> 3. Factors out the call to the same function >> 4. Prevent to enter the cpuidle framework with its expensive cost in >> calculation >> >> As the latency_req is needed in all the cases, change the select API to take >> the latency_req as parameter in case it is not equal to zero. >> >> As a positive side effect, it introduces the latency constraint specified >> externally, so one more step to the cpuidle/scheduler integration. > > I'm expecting to see a new version of this patchset relatively soon. > > Are you planning to send one?
I would like to find an agreement with Preeti. But, yes, I am on it.
-- Daniel
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