Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during per-process profiling of STREAM benchmark on Intel Xeon Phi

From: Andi Kleen
Date: Mon Jun 19 2017 - 10:59:15 EST

> > For comparison, can you give --per-thread a go prior to these patches
> > being applied?
> FWIW, I had a go with (an old) perf record on an arm64 system using
> --per-thread, and I see that no samples are recorded, which seems like a
> bug.
> With --per-thread, the slwodown was ~20%, whereas with the defaults it
> was > 400%.

I'm not sure what the point of the experiment is? It has to work
with reasonable overead even without --per-thread.

FWIW Alexey already root caused the problem, so there's no need
to restart the debugging.