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SubjectRe: perf stat stddev reporting broken since "perf stat: Introduce read_counters function"
On Tue, Jan 19, 2016 at 09:38:12AM +0000, Mel Gorman wrote:
> On Tue, Jan 19, 2016 at 09:16:23AM +0100, Jiri Olsa wrote:
> > On Tue, Jan 19, 2016 at 08:42:28AM +0100, Jiri Olsa wrote:
> >
> > SNIP
> >
> > > >
> > > > Performance counter stats for 'sleep 1' (5 runs):
> > > >
> > > > 0.583178 task-clock (msec) # 0.001 CPUs utilized
> > > > 1 context-switches # 0.002 M/sec
> > > > 0 cpu-migrations # 0.000 K/sec
> > > > 67 page-faults # 0.141 M/sec
> > > > 1,224,416 cycles # 2.585 GHz
> > > > <not supported> stalled-cycles-frontend
> > > > <not supported> stalled-cycles-backend
> > > > 892,568 instructions # 0.68 insns per cycle
> > > > 184,975 branches # 390.554 M/sec
> > > > 8,512 branch-misses # 4.57% of all branches
> > > >
> > > > 1.000889249 seconds time elapsed ( +- 0.01% )
> > > >
> > > > I checked and current master in Linus' tree is also broken. Is this
> > > > change in documented perf stat behaviour intentional?
> > >
> > > nope, not intentional.. I'll check on that, thanks for reporting
> >
> > for some reason we initialized the stat every iteration,
> > (the call is also wrong because it's called only over the
> > first res_stats[0])
> >
> > attached patch works for me, could you please test?
> > I'll run more tests and put it in my queue
> >
>
> That works for me too, thanks. Feel free to put this on the patch;
>
> Tested-by: Mel Gorman <mgorman@techsingularity.net>
>
> When you send it through, can you make sure it has the following please?
>
> Cc: stable@vger.kernel.org # v4.2+

will do, thanks

jirka

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