Re: [PATCH] Minor improvements for perf script flamegraph

[Namhyung Kim]

Hello,

On Tue, Jun 03, 2025 at 03:10:48PM +0800, Tianyou Li wrote:
> When processing the perf data file generated with multiple events,
> the flamegraph script will count all the events regardless of
> different event names. If specify the perf data file with -i option,
> the script will try to read the header information regardless of
> the file name specified, instead it will try to access the perf.data.
> 
> This patch tries to add a -e option to specify the event name that
> the flamegraph will be generated accordingly. If the -e option omitted,
> the behavior remains unchanged. If the -i option specified, the header
> information will be read from that file.

Looks like two separate changes.  Can you please split them?

Thanks,
Namhyung

> 
> Signed-off-by: Tianyou Li <tianyou.li@xxxxxxxxx>
> Reviewed-by: Pan Deng <pan.deng@xxxxxxxxx>
> Reviewed-by: Zhiguo Zhou <zhiguo.zhou@xxxxxxxxx>
> Reviewed-by: Wangyang Guo <wangyang.guo@xxxxxxxxx>
> Reviewed-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
> ---
>  tools/perf/scripts/python/flamegraph.py | 21 +++++++++++++++++++--
>  1 file changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/scripts/python/flamegraph.py b/tools/perf/scripts/python/flamegraph.py
> index cf7ce8229a..eb78b93925 100755
> --- a/tools/perf/scripts/python/flamegraph.py
> +++ b/tools/perf/scripts/python/flamegraph.py
> @@ -94,6 +94,11 @@ class FlameGraphCLI:
>          return child
>  
>      def process_event(self, event):
> +        # ignore events where the event name does not match
> +        # the one specified by the user
> +        if self.args.event_name and event.get("ev_name") != self.args.event_name:
> +            return
> +
>          pid = event.get("sample", {}).get("pid", 0)
>          # event["dso"] sometimes contains /usr/lib/debug/lib/modules/*/vmlinux
>          # for user-space processes; let's use pid for kernel or user-space distinction
> @@ -123,8 +128,15 @@ class FlameGraphCLI:
>              return ""
>  
>          try:
> -            output = subprocess.check_output(["perf", "report", "--header-only"])
> -            return output.decode("utf-8")
> +            if self.args.input:
> +                output = subprocess.check_output(["perf", "script", "--header-only", "-i", self.args.input])
> +            else:
> +                output = subprocess.check_output(["perf", "report", "--header-only"])
> +
> +            result = output.decode("utf-8")
> +            if self.args.event_name:
> +                result += "\nFocused event: " + self.args.event_name
> +            return result
>          except Exception as err:  # pylint: disable=broad-except
>              print("Error reading report header: {}".format(err), file=sys.stderr)
>              return ""
> @@ -235,6 +247,11 @@ if __name__ == "__main__":
>                          default=False,
>                          action="store_true",
>                          help="allow unprompted downloading of HTML template")
> +    parser.add_argument("-e", "--event",
> +                        default="",
> +                        dest="event_name",
> +                        type=str,
> +                        help="specify the event to generate flamegraph for")
>  
>      cli_args = parser.parse_args()
>      cli = FlameGraphCLI(cli_args)
> -- 
> 2.43.5
>