Messages in this thread | | | Subject | Re: [PATCH V2] sched: fair: Use the earliest break even | From | Daniel Lezcano <> | Date | Fri, 13 Mar 2020 14:17:55 +0100 |
| |
On 13/03/2020 14:15, Vincent Guittot wrote: > On Fri, 13 Mar 2020 at 13:15, Daniel Lezcano <daniel.lezcano@linaro.org> wrote:
[ ... ]
>>>>>> + >>>>>> + if (idle_state) >>>>>> + idle_set_break_even(rq, ktime_get_ns() + >>>>> >>>>> What worries me a bit is that it adds one ktime_get call each time a >>>>> cpu enters idle >>>> >>>> Right, we can improve this in the future by folding the local_clock() in >>>> cpuidle when entering idle with this ktime_get. >>> >>> Using local_clock() would be more latency friendly >> >> Unfortunately we are comparing the deadline across CPUs, so the >> local_clock() can not be used here. >> >> But if we have one ktime_get() instead of a local_clock() + ktime_get(), >> that should be fine, no? > > Can't this computation of break_even be done in cpuidle framework > while computing other statistics for selecting the idle state instead > ? cpuidle already uses ktime_get for next hrtimer as an example. > So cpuidle compute break_even and make it available to scheduler like > exit_latency. And I can imagine that system wide time value will also > be needed when looking at next wakeup event of cluster/group of CPUs
Ok, so you suggest to revisit and consolidate the whole time capture in cpuidle? I think that makes sense.
-- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs
Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog
| |