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Message-ID: <CAP-5=fW2--aUG9=14R8fqSEJQN-D3PATTwU15czWVsQidA51bA@mail.gmail.com>
Date: Thu, 1 May 2025 09:04:43 -0700
From: Ian Rogers <irogers@...gle.com>
To: Gautam Menghani <gautam@...ux.ibm.com>
Cc: peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
namhyung@...nel.org, mark.rutland@....com, alexander.shishkin@...ux.intel.com,
jolsa@...nel.org, adrian.hunter@...el.com, kan.liang@...ux.intel.com,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
maddy@...ux.ibm.com
Subject: Re: [PATCH 4/4] perf python: Add counting.py as example for counting
perf events
On Thu, May 1, 2025 at 2:37 AM Gautam Menghani <gautam@...ux.ibm.com> wrote:
>
> Add counting.py - a python version of counting.c to demonstrate
> measuring and reading of counts for given perf events.
>
> Signed-off-by: Gautam Menghani <gautam@...ux.ibm.com>
> ---
> tools/perf/python/counting.py | 41 +++++++++++++++++++++++++++++++++++
> 1 file changed, 41 insertions(+)
> create mode 100755 tools/perf/python/counting.py
>
> diff --git a/tools/perf/python/counting.py b/tools/perf/python/counting.py
> new file mode 100755
> index 000000000000..0c58907bd8bf
> --- /dev/null
> +++ b/tools/perf/python/counting.py
> @@ -0,0 +1,41 @@
> +#!/usr/bin/env python3
> +# SPDX-License-Identifier: GPL-2.0
> +# -*- python -*-
> +# -*- coding: utf-8 -*-
> +
> +import perf
> +
> +def main():
> + cpus = perf.cpu_map()
> + thread_map = perf.thread_map(-1)
> + evlist = perf.evlist(cpus, thread_map)
> +
> + evsel1 = perf.evsel(type = perf.TYPE_SOFTWARE,
> + config = perf.COUNT_SW_CPU_CLOCK,
> + read_format = perf.FORMAT_TOTAL_TIME_ENABLED | perf.FORMAT_TOTAL_TIME_RUNNING,
> + disabled=1)
> + evlist.add(evsel1)
> +
> + evsel2 = perf.evsel(type = perf.TYPE_SOFTWARE,
> + config = perf.COUNT_SW_TASK_CLOCK,
> + read_format = perf.FORMAT_TOTAL_TIME_ENABLED | perf.FORMAT_TOTAL_TIME_RUNNING,
> + disabled=1)
> + evlist.add(evsel2)
Nice example! Would this be better as:
```
cpus = perf.cpu_map()
threads = perf.thread_map(-1)
evlist = perf.parse_events("cpu-clock,task-clock", cpus, threads)
```
If you run `perf stat -vv -e 'cpu-clock,task-clock' .. ` you can
double check the perf event attribute bits. For example in
tracepoint.py we remove the SAMPLE_IP:
https://web.git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/python/tracepoint.py?h=perf-tools-next#n27
> +
> + evlist.open()
> + evlist.enable()
> +
> + count = 100000
> + while count > 0:
> + count -= 1
> +
> + evlist.disable()
> + evsel = evlist.next(None)
> + while evsel != None:
> + counts = evsel.read(0, 0)
Rather than just reading on the first CPU and thread, perhaps change
to iterate over the cpus and threads? Something like:
```
for evsel in evlist:
for cpu in cpus:
for thread in threads:
counts = evsel.read(cpu, thread)
print(f"For {evsel} read val={counts.val}
enable={counts.ena} run ={counts.run}")
```
Thanks,
Ian
> + print(counts.val, counts.ena, counts.run)
> + evsel = evlist.next(evsel)
> + evlist.close()
> +
> +if __name__ == '__main__':
> + main()
> --
> 2.49.0
>
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