Messages in this thread |  | | Date | Wed, 15 Apr 2015 14:50:33 +0200 | From | Daniel Lezcano <> | Subject | Re: [PATCH 1/3] cpuidle: Store the idle start time stamp |
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On 04/15/2015 02:42 PM, Peter Zijlstra wrote: > On Wed, Apr 15, 2015 at 02:29:06PM +0200, Daniel Lezcano wrote: >> On 04/15/2015 12:20 PM, Peter Zijlstra wrote: >>> On Wed, Apr 15, 2015 at 12:00:22PM +0200, Daniel Lezcano wrote: >>>> + target_state->idle_stamp = ktime_to_us(ktime_get()); >>> >>> ktime_get_ns(); >>> >> >> Hmm, sounds like I missed we are dealing with different units (us / ns) in >> cpuidle / sched. >> >> Would it make sense to store the time into a ktime structure instead and use >> the relevant function depending on the place we are inspecting the value >> from ? > > Why would you ever want to use us? Does ARM enjoy calculating /1000? > > Ah, I see the !scalar ktime got whacked, good! At which point the u64 ns > and ktime are the same. That said I prefer the u64 over ktime because > its easier to manipulate.
Ok. I was trying to save one variable on the stack by reusing the idle_stamp value but if we store it in a different unit, then we have to keep it in order to have usecond for the governors.
I was thinking about converting to nanosecond the cpuidle framework but it is not worth to do that as the resolution is too high for the idle states.
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