linux-kernel - Re: [PATCH 3/4] perf archive: Fix filtering of empty build-ids

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Message-ID: <20210212122901.GB1398414@kernel.org>
Date:   Fri, 12 Feb 2021 09:29:01 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Nicholas Fraser <nfraser@...eweavers.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        "Frank Ch. Eigler" <fche@...hat.com>,
        Song Liu <songliubraving@...com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Kim Phillips <kim.phillips@....com>,
        Tommi Rantala <tommi.t.rantala@...ia.com>,
        Remi Bernon <rbernon@...eweavers.com>,
        linux-kernel@...r.kernel.org,
        Ulrich Czekalla <uczekalla@...eweavers.com>,
        Huw Davies <huw@...eweavers.com>
Subject: Re: [PATCH 3/4] perf archive: Fix filtering of empty build-ids

Em Wed, Feb 10, 2021 at 02:17:49PM -0500, Nicholas Fraser escreveu:
> 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 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>
> ---
>  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

What should we do when using older files? We have to support both cases.

- Arnaldo