From: Andi Kleen <ak@linux.intel.com>
To: kan.liang@intel.com
Cc: a.p.zijlstra@chello.nl, mingo@redhat.com, acme@kernel.org,
eranian@google.com, mark.rutland@arm.com,
adrian.hunter@intel.com, dsahern@gmail.com, jolsa@kernel.org,
namhyung@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 8/9] perf,tools: caculate and save tsc/avg/bzy freq in he_stat
Date: Fri, 17 Jul 2015 13:25:53 -0700 [thread overview]
Message-ID: <20150717202553.GG7380@tassilo.jf.intel.com> (raw)
In-Reply-To: <1437078831-10152-9-git-send-email-kan.liang@intel.com>
> + if (sample->read.time_running > 0) {
> + freq.tsc_freq = (1000 * sample->tsc) / sample->read.time_running;
> + freq.avg_freq = (1000 * sample->aperf) / sample->read.time_running;
> + if (sample->aperf > 0)
> + freq.bzy_freq = freq.tsc_freq * sample->mperf / sample->aperf;
Sorry didn't notice that earlier. The formula is not correct.
aperf/mperf is not necessarily the frequency, it is essentially a load average
of the CPU. It should be reported as such. Also only the ratio is
architecturally defined.
The right way to compute frequency is cycles / ref-cycles
TSC can be used to accurately compute CPU utilization tsc / ref-cycles
It would be useful to report all three metrics.
-Andi
next prev parent reply other threads:[~2015-07-17 20:25 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-16 20:33 [PATCH 0/9] Intel core misc PMUs support kan.liang
2015-07-16 20:33 ` [PATCH 1/9] perf/x86: Add " kan.liang
2015-07-16 20:33 ` [PATCH 2/9] perf/x86: core_misc PMU disable and enable support kan.liang
2015-07-17 12:11 ` Mark Rutland
2015-07-17 13:46 ` Peter Zijlstra
2015-07-17 13:51 ` Peter Zijlstra
2015-07-17 15:35 ` Liang, Kan
2015-07-17 17:01 ` Andy Lutomirski
2015-07-17 17:52 ` Liang, Kan
2015-07-17 17:58 ` Andy Lutomirski
2015-07-17 18:15 ` Liang, Kan
2015-07-17 18:56 ` Andy Lutomirski
2015-07-17 21:11 ` Peter Zijlstra
2015-07-16 20:33 ` [PATCH 3/9] perf/x86: Add is_hardware_event kan.liang
2015-07-17 10:48 ` Mark Rutland
2015-07-17 15:03 ` Liang, Kan
2015-07-17 15:47 ` Mark Rutland
2015-07-17 16:11 ` Mark Rutland
2015-07-16 20:33 ` [PATCH 4/9] perf/x86: special case per-cpu core misc PMU events kan.liang
2015-07-17 12:21 ` Mark Rutland
2015-07-17 12:55 ` Peter Zijlstra
2015-07-17 18:11 ` Stephane Eranian
2015-07-17 20:17 ` Andi Kleen
2015-07-20 16:12 ` Mark Rutland
2015-07-16 20:33 ` [PATCH 5/9] perf,tools: open event with it's own cpus and threads kan.liang
2015-07-16 20:33 ` [PATCH 6/9] perf,tools: Dump per-sample freq in report -D kan.liang
2015-07-16 20:33 ` [PATCH 7/9] perf,tools: save APERF/MPERF/TSC in struct perf_sample kan.liang
2015-07-16 20:33 ` [PATCH 8/9] perf,tools: caculate and save tsc/avg/bzy freq in he_stat kan.liang
2015-07-17 20:25 ` Andi Kleen [this message]
2015-07-17 20:57 ` Liang, Kan
2015-07-17 21:27 ` Andi Kleen
2015-07-16 20:33 ` [PATCH 9/9] perf,tools: Show freq in perf report --stdio kan.liang
2015-07-17 11:39 ` [PATCH 0/9] Intel core misc PMUs support Ingo Molnar
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