From: Alan Egerton <eggyal@gmail.com>
To: linux-perf-users@vger.kernel.org
Subject: Percentages reported by `perf stat --hybrid-merge`
Date: Mon, 15 Apr 2024 19:50:08 +0100 [thread overview]
Message-ID: <CA+phaecbKJXE56ExeJUA5c2=tc3m3p8iNefuqyjs9P3kOn_aWg@mail.gmail.com> (raw)
Hi,
I'm struggling to understand the intended semantics of the percentage
field in `--hybrid-merge` results.
I'm looking at both the `instructions` and `cycles` counters on an
Apple M1 Ultra (so 4 "apple_icestorm_pmu" cores and 16
"apple_firestorm_pmu" cores), but with `--hybrid-merge` the
percentages consistently read `80.00` (which curiously is the
proportion of cores that are firestorm) instead of `100.00` as I had
expected.
Whilst I see the following mentioned in the manual, I can't quite grok
how it applies:
> perf-stat reports the scaled counts for hybrid event and with a percentage displayed. The percentage is the event’s running time/enabling time.
Could someone possibly explain why my 100% expectation was wrong and
how the percentage is actually calculated?
Many thanks,
Alan
next reply other threads:[~2024-04-15 18:50 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-15 18:50 Alan Egerton [this message]
2024-04-15 19:30 ` Percentages reported by `perf stat --hybrid-merge` Alan Egerton
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