On Mon, 2018-01-08 at 09:31 +0530, Viresh Kumar wrote: > On 05-01-18, 23:18, Rafael J. Wysocki wrote: > > On Fri, Jan 5, 2018 at 9:37 PM, Leonard Crestez <leonard.cres...@nxp.com> > > wrote:
> > > When using the schedutil governor together with the softlockup detector > > > all CPUs go to their maximum frequency on a regular basis. This seems > > > to be because the watchdog creates a RT thread on each CPU and this > > > causes regular kicks with: > > > > > > cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_RT); > > > > > > The schedutil governor responds to this by immediately setting the > > > maximum cpu frequency, this is very undesirable. > > > > > > The issue can be fixed by this patch from android: > > > > > > The patch stalled in a long discussion about how it's difficult for > > > cpufreq to deal with RT and how some RT users might just disable > > > cpufreq. It is indeed hard but if the system experiences regular power > > > kicks from a common debug feature they will end up disabling schedutil > > > instead. > > Patrick has a series of patches dealing with this problem area AFAICS, > > but we are currently integrating material from Juri related to > > deadline tasks. > I am not sure if Patrick's patches would solve this problem at all as > we still go to max for RT and the RT task is created from the > softlockup detector somehow. I assume you're talking about the series starting with "[PATCH v3 0/6] cpufreq: schedutil: fixes for flags updates" I checked and they have no effect on this particular issue (not surprising). -- Regards, Leonard
