On Thu, Jun 07, 2018 at 09:01:30AM -0700, Stephane Eranian wrote: > Hi Jiri, > > On Thu, Jun 7, 2018 at 8:45 AM Andi Kleen <[email protected]> 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.
right.. I guess we can survive few seconds of misleading idle counts and perhaps we could detect nohz is enabled and warn about this thanks, jirka
