linux-kernel - Re: [PATCH v2 11/11] perf python tracepoint: Switch to using parse

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Message-ID: <Z89k6lWxRSBfCGvM@google.com>
Date: Mon, 10 Mar 2025 15:17:14 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Yicong Yang <yangyicong@...ilicon.com>,
	James Clark <james.clark@...aro.org>,
	"Dr. David Alan Gilbert" <linux@...blig.org>,
	Levi Yun <yeoreum.yun@....com>, Ze Gao <zegao2021@...il.com>,
	Weilin Wang <weilin.wang@...el.com>, Xu Yang <xu.yang_2@....com>,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
	Howard Chu <howardchu95@...il.com>
Subject: Re: [PATCH v2 11/11] perf python tracepoint: Switch to using
 parse_events

On Fri, Feb 28, 2025 at 02:23:08PM -0800, Ian Rogers wrote:
> Rather than manually configuring an evsel, switch to using
> parse_events for greater commonality with the rest of the perf code.
> 
> Reviewed-by: Howard Chu <howardchu95@...il.com>
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
>  tools/perf/python/tracepoint.py | 23 +++++++++++------------
>  1 file changed, 11 insertions(+), 12 deletions(-)
> 
> diff --git a/tools/perf/python/tracepoint.py b/tools/perf/python/tracepoint.py
> index bba68a6d4515..38b2b6d11f64 100755
> --- a/tools/perf/python/tracepoint.py
> +++ b/tools/perf/python/tracepoint.py
> @@ -5,24 +5,23 @@
>  
>  import perf
>  
> -class tracepoint(perf.evsel):
> -    def __init__(self, sys, name):
> -        config = perf.tracepoint(sys, name)
> -        perf.evsel.__init__(self,
> -                            type   = perf.TYPE_TRACEPOINT,
> -                            config = config,
> -                            freq = 0, sample_period = 1, wakeup_events = 1,
> -                            sample_type = perf.SAMPLE_PERIOD | perf.SAMPLE_TID | perf.SAMPLE_CPU | perf.SAMPLE_RAW | perf.SAMPLE_TIME)
> -
>  def main():
> -    tp      = tracepoint("sched", "sched_switch")
>      cpus    = perf.cpu_map()
>      threads = perf.thread_map(-1)
> +    evlist = perf.parse_events("sched:sched_switch", cpus, threads)
> +    # Disable tracking of mmaps and similar that are unnecessary.
> +    for ev in evlist:
> +        ev.tracking = False
> +    # Configure evsels with default record options.
> +    evlist.config()

I think the default option uses frequency of 4000 but tracepoints want
to use period of 1.  Also I'm not sure if it sets the proper sample type
bits namely PERF_SAMPLE_RAW.

Thanks,
Namhyung


> +    # Simplify the sample_type and read_format of evsels
> +    for ev in evlist:
> +        ev.sample_type = ev.sample_type & ~perf.SAMPLE_IP
> +        ev.read_format = 0
>  
> -    evlist = perf.evlist(cpus, threads)
> -    evlist.add(tp)
>      evlist.open()
>      evlist.mmap()
> +    evlist.enable();
>  
>      while True:
>          evlist.poll(timeout = -1)
> -- 
> 2.48.1.711.g2feabab25a-goog
>