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Re: [PATCH 2/4] perf stat: Add computation of TopDown formulas

From Andi Kleen <ak@linux.intel.com>
Newsgroups linux.kernel
Subject Re: [PATCH 2/4] perf stat: Add computation of TopDown formulas
Date 2016-06-01 17:00 +0200
Message-ID <rFfMJ-1eo-15@gated-at.bofh.it> (permalink)
References <rCqEG-7B3-11@gated-at.bofh.it> <rCqEG-7B3-9@gated-at.bofh.it> <rFfMJ-1eo-17@gated-at.bofh.it>
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On Wed, Jun 01, 2016 at 09:50:07AM -0500, Nilay Vaish wrote:
> On 24 May 2016 at 14:52, Andi Kleen <andi@firstfloor.org> wrote:
> > +static double td_be_bound(int ctx, int cpu)
> > +{
> > +       double sum = (td_fe_bound(ctx, cpu) +
> > +                     td_bad_spec(ctx, cpu) +
> > +                     td_retiring(ctx, cpu));
> > +       if (sum == 0)
> > +               return 0;
> > +       return sanitize_val(1.0 - sum);
> > +}
> > +
> 
> Can you explain why we need the check on sum?

You mean the if statement?

Otherwise if nothing was measured it would always report everything backend bound,
which wouldn't be correct.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only

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Thread

Re: [PATCH 2/4] perf stat: Add computation of TopDown formulas Nilay Vaish <nilayvaish@gmail.com> - 2016-06-01 17:00 +0200
  Re: [PATCH 2/4] perf stat: Add computation of TopDown formulas Andi Kleen <ak@linux.intel.com> - 2016-06-01 17:00 +0200
    Re: [PATCH 2/4] perf stat: Add computation of TopDown formulas Nilay Vaish <nilayvaish@gmail.com> - 2016-06-02 14:10 +0200
      Re: [PATCH 2/4] perf stat: Add computation of TopDown formulas Andi Kleen <andi@firstfloor.org> - 2016-06-02 16:30 +0200

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