linux-kernel - Re: [PATCH 1/2] perf archive: Fix filtering of empty build-ids

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Date:   Wed, 24 Feb 2021 14:50:20 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Nicholas Fraser <nfraser@...eweavers.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>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>, linux-kernel@...r.kernel.org,
        Ulrich Czekalla <uczekalla@...eweavers.com>,
        Huw Davies <huw@...eweavers.com>
Subject: Re: [PATCH 1/2] perf archive: Fix filtering of empty build-ids

On Fri, Feb 19, 2021 at 11:09:32AM -0500, Nicholas Fraser wrote:
> A non-existent build-id used to be treated as all-zero SHA-1 hash.
> Build-ids are now variable width. A non-existent build-id is an empty
> string and "perf buildid-list" pads this with spaces. This is true even
> when using old perf.data files recorded from older versions of perf;
> "perf buildid-list" never reports an all-zero hash anymore.
> 
> This fixes "perf-archive" to skip missing build-ids by skipping lines
> that start with a padding space rather than with zeroes.
> 
> Signed-off-by: Nicholas Fraser <nfraser@...eweavers.com>

Acked-by: Jiri Olsa <jolsa@...hat.com>

thanks,
jirka

> ---
>  tools/perf/perf-archive.sh | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/tools/perf/perf-archive.sh b/tools/perf/perf-archive.sh
> index 0cfb3e2cefef..133f0eddbcc4 100644
> --- a/tools/perf/perf-archive.sh
> +++ b/tools/perf/perf-archive.sh
> @@ -20,9 +20,8 @@ else
>  fi
>  
>  BUILDIDS=$(mktemp /tmp/perf-archive-buildids.XXXXXX)
> -NOBUILDID=0000000000000000000000000000000000000000
>  
> -perf buildid-list -i $PERF_DATA --with-hits | grep -v "^$NOBUILDID " > $BUILDIDS
> +perf buildid-list -i $PERF_DATA --with-hits | grep -v "^ " > $BUILDIDS
>  if [ ! -s $BUILDIDS ] ; then
>  	echo "perf archive: no build-ids found"
>  	rm $BUILDIDS || true
> -- 
> 2.30.1
>