Re: [PATCH v1 22/41] perf script: Don't drop metric samples for CPUs missing from the evsel

[sashiko-bot@kernel.org]

> perf script -F metric looks up the index of the sample's CPU in the
> evsel's CPU map and, when it isn't present, prints "Missing CPU map
> entry for CPU <n>" and ignores the sample. When the perf.data file
> doesn't record the CPUs of an event, as is the case for perf record,
> __perf_evlist__propagate_maps() sets the evsel's CPUs to the host's
> online CPUs. If a CPU is offline when perf script is run, or the
> perf.data file was recorded on a machine with more CPUs, then every
> sample on such a CPU is dropped from the metrics with a message, for
> example thousands of:
> 
>   Missing CPU map entry for CPU 1
> 
> perf script currently only supports global aggregation of the counts
> used for metrics, the counts of all CPUs are summed. So place the counts
> of a sample whose CPU isn't in the evsel's CPU map in the first CPU of
> the map, as was already done for samples without a CPU. This doesn't
> change the metric values computed for samples of the CPUs in the map,
> the summed counts just include the previously dropped samples, and so
> isn't a regression. Aggregating per CPU, and using the CPUs of the
> perf.data file's environment rather than the host's, would be future
> improvements.
> 
> Fixes: 3622990efaab ("perf script: Change metric format to use json metrics")
> Signed-off-by: Ian Rogers <irogers@google.com>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261103234502.1008382-1-irogers@google.com?part=22