Re: [PATCH v7 1/5] perf report: properly handle branch count in match_chain

From: Andi Kleen
Date: Mon Oct 23 2017 - 11:15:18 EST


Milian Wolff <milian.wolff@xxxxxxxx> writes:
>
> perf record -b --call-graph dwarf <some binary>
> perf report --branch-history --no-children --stdio
>
> I see predicted and iter values as before, so I think nothing is breaking. But
> I'm somewhat unsure. Can someone paste an example source code and the perf
> commands to get some meaningful avg_cycles? Or does this depend on a newer
> Intel CPU? I have currently only a Intel(R) Core(TM) i7-5600U CPU @ 2.60GHz
> available.

Branch cycles requires at least a Skylake or Goldmont CPU, so yes.

For testing on other systems you can fake them however with some variant
of this patch

http://lkml.iu.edu/hypermail//linux/kernel/1505.1/01135.html

-Andi