On Wed, Sep 30, 2020 at 05:16:29PM +0800, jun qian wrote: > Peter Zijlstra <[email protected]> 于2020年9月30日周三 下午4:20写道： > > > > On Wed, Sep 30, 2020 at 10:47:12AM +0800, [email protected] wrote: > > > From: jun qian <[email protected]> > > > > > > When the sched_schedstat changes from 0 to 1, some sched se maybe > > > already in the runqueue, the se->statistics.wait_start will be 0. > > > So it will let the (rq_of(cfs_rq)) - se->statistics.wait_start) > > > wrong. We need to avoid this scenario. > > > > Is this really the only problem there? Did you do a full audit of that > > schedstat nonsense? > > > > Did you mean that the sched_stat_xxx's xxx_start(sched_stat_sleep > sched_stat_iowait sched_stat_blocked > sched_stat_runtime) may be also depend the schedstat_enabled?
Yeah, this runtime schedstat_enabled thing is fairly recent, it used to be an always on/off kinda thing. At the time we figured inconsistencies from dynamically enabling/disabling it were okay, it's just stats after all. But if you now want to 'fix' that, then a full audit might be nice. > I have searched the codes, and found that these sched_stat_xxx's > xxx_start don't depend the schedstat_enabled > except the wait_start. OK, so you did the audit and only found this one issue? That's good Changelog material :-) Thanks!
