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

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Message-ID: <20190129105337.GA17762@kernel.org>
Date:   Tue, 29 Jan 2019 11:53:37 +0100
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Alexey Budankov <alexey.budankov@...ux.intel.com>
Cc:     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>,
        Andi Kleen <ak@...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

Em Tue, Jan 29, 2019 at 11:45:43AM +0100, Arnaldo Carvalho de Melo escreveu:
> 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?
> 
>   $ ldd ~/bin/perf | wc -l
>   30
>   $ ldd ~/bin/perf | grep z
> 	liblzma.so.5 => /lib64/liblzma.so.5 (0x00007f3dcc356000)
> 	libz.so.1 => /lib64/libz.so.1 (0x00007f3dcb2aa000)
> 	libbz2.so.1 => /lib64/libbz2.so.1 (0x00007f3dcb218000)
>   $
> 
> Humm, from the github page it says:
> 
> -----
> The project is provided as an open-source dual BSD and GPLv2 licensed C
> library, and a command line utility producing and decoding .zst, .gz,
> .xz and .lz4 files. Should your project require another programming
> language, a list of known ports and bindings is provided on Zstandard
> homepage.
> -----
> 
> So it would cover just liblzma and libz, right?

Nevermind;

[acme@...co perf]$ zstdcat ~/git/perf/perf-5.0.0-rc2.tar.xz
zstd: /home/acme/git/perf/perf-5.0.0-rc2.tar.xz: xz/lzma file cannot be uncompressed (zstd compiled without HAVE_LZMA) -- ignored

So it handles those formats, _if_ linked with those libraries, duh.

- Arnaldo