Re: [BUG] schedutil governor produces regular max freq spikes because of lockup detector watchdog threads
From: Viresh Kumar
Date: Tue Jan 09 2018 - 23:08:37 EST
On 09-01-18, 16:43, Leonard Crestez wrote:
> What I am saying is that as far as I can tell when cpufreq_update_util
> is called when the task has already executed and is been switched out.
Can you check if this patch makes it any better ?
https://marc.info/?l=linux-kernel&m=151204248901636&w=2
> My tests are not very elaborate but based on some ftracing it seems to
> me that the current behavior is for cpufreq spikes to always trail RT
> activity. Like this:
>
> <idle>-0 [002] 496.510138: sched_switch: swapper/2:0 [120] S ==> watchdog/2:20 [0]
> watchdog/2-20 [002] 496.510156: bprint: watchdog: IN watchdog(2)
> watchdog/2-20 [002] 496.510364: bprint: watchdog: OU watchdog(2)
> watchdog/2-20 [002] 496.510377: bprint: update_curr_rt: watchdog kick RT! cpu=2 comm=watchdog/2
Probabl update_curr_rt is getting called a bit after the task has
already run. The above patch moves the call to cpufreq_update_util()
to enqueue/dequeue paths and that should fix it.
--
viresh