From: Andi Kleen <ak@linux.intel.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Kan Liang <kan.liang@intel.com>,
Dmitri Prokhorov <Dmitry.Prohorov@intel.com>,
Valery Cherepennikov <valery.cherepennikov@intel.com>,
David Carrillo-Cisneros <davidcc@google.com>,
Stephane Eranian <eranian@google.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during per-process profiling of STREAM benchmark on Intel Xeon Phi
Date: Mon, 19 Jun 2017 07:59:08 -0700 [thread overview]
Message-ID: <20170619145908.GA23705@tassilo.jf.intel.com> (raw)
In-Reply-To: <20170619133831.GB3894@leverpostej>
> > 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.
-Andi
next prev parent reply other threads:[~2017-06-19 14:59 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-15 17:41 [PATCH v3 1/n] perf/core: addressing 4x slowdown during per-process profiling of STREAM benchmark on Intel Xeon Phi Alexey Budankov
2017-06-15 19:56 ` Mark Rutland
2017-06-15 22:10 ` Alexey Budankov
2017-06-16 9:09 ` Mark Rutland
2017-06-16 14:08 ` Alexey Budankov
2017-06-16 14:22 ` Alexey Budankov
2017-06-19 12:46 ` Mark Rutland
2017-06-19 13:38 ` Mark Rutland
2017-06-19 14:09 ` Alexey Budankov
2017-06-19 14:59 ` Andi Kleen [this message]
2017-06-19 15:09 ` Mark Rutland
2017-06-19 15:21 ` Andi Kleen
2017-06-19 15:24 ` Mark Rutland
2017-06-19 15:39 ` Andi Kleen
2017-06-19 15:52 ` Mark Rutland
2017-06-19 13:08 ` Alexey Budankov
2017-06-19 13:26 ` Mark Rutland
2017-06-19 13:37 ` Alexey Budankov
2017-06-19 15:00 ` Alexey Budankov
2017-06-19 15:24 ` Andi Kleen
2017-06-19 15:34 ` Alexey Budankov
2017-06-30 10:23 ` Alexey Budankov
2017-06-30 10:21 ` Alexey Budankov
2017-06-19 15:14 ` Mark Rutland
2017-06-19 15:27 ` Alexey Budankov
2017-06-30 10:21 ` Alexey Budankov
2017-06-19 20:31 ` Alexey Budankov
2017-06-20 13:36 ` Mark Rutland
2017-06-20 15:22 ` Alexey Budankov
2017-06-20 16:37 ` Mark Rutland
2017-06-20 17:10 ` Alexey Budankov
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