Re: [PATCH v4 2/3] perf python: Add alpha-profileme.py

[sashiko-bot@kernel.org]

> perf report shows where Alpha ProfileMe samples land but cannot
> aggregate the raw status attached to them.
> 
> Add a standalone script, using the perf Python module, that summarizes
> it by symbol or, with --pc, by instruction, in the style of DCPI: the
> fraction of samples killed on a wrong path, not retired, mispredicted,
> taken or stalled, the mean PCTR1 window count, and trap counts by type.
> Mispredict and trap types are only counted when I_STAT[TRP] is set
> and the instruction was not killed before it was mapped, since they are
> stale otherwise. Redirect traps are counted by their
> PALcode entry offset in PMPC.
> 
> Raw data is only read from cpu PMU events, as a tracepoint's payload can
> pass for ProfileMe status. Rows are kept apart by PCTR_CTL[SL1], as a
> mean over two things PCTR1 can count means nothing.
> 
> On an EV7, sampling a loop whose branch tests random data reports that
> branch mispredicted in 21% of its samples, and 0% with sorted data.
> 
> Signed-off-by: Matt Turner <mattst88@gmail.com>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261104-perf-alpha-profileme-v4-0-1771ea02950e@gmail.com?part=2