Messages in this thread | | | From | Stephane Eranian <> | Date | Thu, 7 Jun 2018 09:01:30 -0700 | Subject | Re: [PATCH 09/10] perf/cputime: Don't stop idle tick if there's live cputime event |
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Hi Jiri,
On Thu, Jun 7, 2018 at 8:45 AM Andi Kleen <andi@firstfloor.org> wrote: > > On Thu, Jun 07, 2018 at 12:15:12AM +0200, Jiri Olsa wrote: > > Disable stopping of the idle tick when having live cputime > > event. When the tick is disabled, the idle counts are out > > of date until next tick/update and perf cputime PMU provides > > misleading counts. > > I really don't like this. This can totally change performance > (e.g. less Turbo due to less idle) and performance tools shouldn't > change the performance profile drastically. > You do not want to change the behavior of the kernel just because you are monitoring. This may introduce side effects on other events which may not otherwise exist.
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