linux-kernel - Re: [PATCH v2 0/4] perf: enable compression of record mode trace to save storage space

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Date:   Tue, 29 Jan 2019 09:25:30 -0800
From:   Andi Kleen <ak@...ux.intel.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Alexey Budankov <alexey.budankov@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 0/4] perf: enable compression of record mode trace to
 save storage space

On Tue, Jan 29, 2019 at 11:45:43AM +0100, Arnaldo Carvalho de Melo wrote:
> Em Mon, Jan 28, 2019 at 09:40:28AM +0300, Alexey Budankov escreveu:
> > The patch set implements runtime trace compression for record mode and 
> > trace file decompression for report mode. Zstandard API [1] is used for 
> > compression/decompression of data that come from perf_events kernel 
> 
> Interesting, wasn't aware of this zstd library, I wonder if we can add
> it and switch the other compression libraries we link against, so that
> we're not adding one more library to the dep list of perf but removing
> some instead, do you think this would be possible?

Sadly we can't because perf needs the existing libraries to uncompress
modules, and they might be compressed with zlib or bzip2. zstd cannot
uncompress those formats.

-Andi