Messages in this thread | | | Date | Tue, 28 Mar 2017 17:30:05 -0400 | From | Luiz Capitulino <> | Subject | Re: [BUG nohz]: wrong user and system time accounting |
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On Tue, 28 Mar 2017 17:24:11 -0400 Rik van Riel <riel@redhat.com> wrote:
> On Tue, 2017-03-28 at 16:14 -0400, Luiz Capitulino wrote: > > > And I think I was right, it looks like the nohz code is programming > > the tick period incorrectly when restarting the tick. The patch below > > fixes things for me, but I still have some homework todo and more > > testing before posting a patch for inclusion. Could you guys test it? > > I spoke too soon. After half an hour of runtime, > things have gotten aligned to give me about 50/50 > user time and system time with your test case, > again.
Hmmm, maybe it's incomplete. I still think that nohz might screwing something up when re-activating the tick.
> > This is on an 8 VCPU virtual machine, with > nohz_full=2-7, and the test case running on one > of the nohz_full CPUs. > > > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c > > index 7fe53be..9abe979 100644 > > --- a/kernel/time/tick-sched.c > > +++ b/kernel/time/tick-sched.c > > @@ -1152,6 +1152,7 @@ static enum hrtimer_restart > > tick_sched_timer(struct hrtimer *timer) > > struct pt_regs *regs = get_irq_regs(); > > ktime_t now = ktime_get(); > > > > + ts->last_tick = now; > > tick_sched_do_timer(now); > > > > /* >
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