From: Jeff King <peff@peff.net>
To: "René Scharfe" <l.s.r@web.de>
Cc: Rohit Ashiwal via GitGitGadget <gitgitgadget@gmail.com>,
Johannes Schindelin <johannes.schindelin@gmx.de>,
git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
Rohit Ashiwal <rohit.ashiwal265@gmail.com>
Subject: Re: [PATCH 2/2] archive: avoid spawning `gzip`
Date: Mon, 15 Apr 2019 17:35:56 -0400 [thread overview]
Message-ID: <20190415213556.GB28128@sigill.intra.peff.net> (raw)
In-Reply-To: <8ef2164c-1d44-33bf-ea8a-49fa0b5c8abf@web.de>
On Sun, Apr 14, 2019 at 12:01:10AM +0200, René Scharfe wrote:
> >> As we already link to the zlib library, we can perform the compression
> >> without even requiring gzip on the host machine.
> >
> > Very cool. It's nice to drop a dependency, and this should be a bit more
> > efficient, too.
>
> Getting rid of dependencies is good, and using zlib is the obvious way to
> generate .tgz files. Last time I tried something like that, a separate gzip
> process was faster, though -- at least on Linux [1]. How does this one
> fare?
I'd expect a separate gzip to be faster in wall-clock time for a
multi-core machine, but overall consume more CPU. I'm slightly surprised
that your timings show that it actually wins on total CPU, too.
Here are best-of-five times for "git archive --format=tar.gz HEAD" on
linux.git (the machine is a quad-core):
[before, separate gzip]
real 0m21.501s
user 0m26.148s
sys 0m0.619s
[after, internal gzwrite]
real 0m25.156s
user 0m25.059s
sys 0m0.096s
which does show what I expect (longer overall, but less total CPU).
Which one you prefer depends on your situation, of course. A user on a
workstation with multiple cores probably cares most about end-to-end
latency and using all of their available horsepower. A server hosting
repositories and receiving many unrelated requests probably cares more
about total CPU (though the differences there are small enough that it
may not even be worth having a config knob to un-parallelize it).
> Doing compression in its own thread may be a good idea.
Yeah. It might even make the patch simpler, since I'd expect it to be
implemented with start_async() and a descriptor, making it look just
like a gzip pipe to the caller. :)
-Peff
next prev parent reply other threads:[~2019-04-15 21:36 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-12 23:04 [PATCH 0/2] Avoid spawning gzip in git archive Johannes Schindelin via GitGitGadget
2019-04-12 23:04 ` [PATCH 1/2] archive: replace write_or_die() calls with write_block_or_die() Rohit Ashiwal via GitGitGadget
2019-04-13 1:34 ` Jeff King
2019-04-13 5:51 ` Junio C Hamano
2019-04-14 4:36 ` Rohit Ashiwal
2019-04-26 14:29 ` Johannes Schindelin
2019-04-26 23:44 ` Junio C Hamano
2019-04-29 21:32 ` Johannes Schindelin
2019-05-01 18:09 ` Jeff King
2019-05-02 20:29 ` René Scharfe
2019-05-05 5:25 ` Junio C Hamano
2019-05-06 5:07 ` Jeff King
2019-04-14 4:34 ` Rohit Ashiwal
2019-04-14 10:33 ` Junio C Hamano
2019-04-26 14:28 ` Johannes Schindelin
2019-05-01 18:07 ` Jeff King
2019-04-12 23:04 ` [PATCH 2/2] archive: avoid spawning `gzip` Rohit Ashiwal via GitGitGadget
2019-04-13 1:51 ` Jeff King
2019-04-13 22:01 ` René Scharfe
2019-04-15 21:35 ` Jeff King [this message]
2019-04-26 14:51 ` Johannes Schindelin
2019-04-27 9:59 ` René Scharfe
2019-04-27 17:39 ` René Scharfe
2019-04-29 21:25 ` Johannes Schindelin
2019-05-01 17:45 ` René Scharfe
2019-05-01 18:18 ` Jeff King
2019-06-10 10:44 ` René Scharfe
2019-06-13 19:16 ` Jeff King
2019-04-13 22:16 ` brian m. carlson
2019-04-15 21:36 ` Jeff King
2019-04-26 14:54 ` Johannes Schindelin
2019-05-02 20:20 ` Ævar Arnfjörð Bjarmason
2019-05-03 20:49 ` Johannes Schindelin
2019-05-03 20:52 ` Jeff King
2019-04-26 14:47 ` Johannes Schindelin
[not found] ` <pull.145.v2.git.gitgitgadget@gmail.com>
[not found] ` <4ea94a8784876c3a19e387537edd81a957fc692c.1556321244.git.gitgitgadget@gmail.com>
2019-05-02 20:29 ` [PATCH v2 3/4] archive: optionally use zlib directly for gzip compression René Scharfe
[not found] ` <ac2b2488a1b42b3caf8a84594c48eca796748e59.1556321244.git.gitgitgadget@gmail.com>
2019-05-02 20:30 ` [PATCH v2 2/4] archive-tar: mark RECORDSIZE/BLOCKSIZE as unsigned René Scharfe
2019-05-08 11:45 ` Johannes Schindelin
2019-05-08 23:04 ` Jeff King
2019-05-09 14:06 ` Johannes Schindelin
2019-05-09 18:38 ` Jeff King
2019-05-10 17:18 ` René Scharfe
2019-05-10 21:20 ` Jeff King
2022-06-12 6:00 ` [PATCH v3 0/5] Avoid spawning gzip in git archive René Scharfe
2022-06-12 6:03 ` [PATCH v3 1/5] archive: rename archiver data field to filter_command René Scharfe
2022-06-12 6:05 ` [PATCH v3 2/5] archive-tar: factor out write_block() René Scharfe
2022-06-12 6:08 ` [PATCH v3 3/5] archive-tar: add internal gzip implementation René Scharfe
2022-06-13 19:10 ` Junio C Hamano
2022-06-12 6:18 ` [PATCH v3 4/5] archive-tar: use OS_CODE 3 (Unix) for internal gzip René Scharfe
2022-06-12 6:19 ` [PATCH v3 5/5] archive-tar: use internal gzip by default René Scharfe
2022-06-13 21:55 ` Junio C Hamano
2022-06-14 11:27 ` Johannes Schindelin
2022-06-14 15:47 ` René Scharfe
2022-06-14 15:56 ` René Scharfe
2022-06-14 16:29 ` Johannes Schindelin
2022-06-14 20:04 ` René Scharfe
2022-06-15 16:41 ` Junio C Hamano
2022-06-14 11:28 ` [PATCH v3 0/5] Avoid spawning gzip in git archive Johannes Schindelin
2022-06-14 20:05 ` René Scharfe
2022-06-30 18:55 ` Johannes Schindelin
2022-07-01 16:05 ` Johannes Schindelin
2022-07-01 16:27 ` Jeff King
2022-07-01 17:47 ` Junio C Hamano
2022-06-15 16:53 ` [PATCH v4 0/6] " René Scharfe
2022-06-15 16:58 ` [PATCH v4 1/6] archive: update format documentation René Scharfe
2022-06-15 16:59 ` [PATCH v4 2/6] archive: rename archiver data field to filter_command René Scharfe
2022-06-15 17:01 ` [PATCH v4 3/6] archive-tar: factor out write_block() René Scharfe
2022-06-15 17:02 ` [PATCH v4 4/6] archive-tar: add internal gzip implementation René Scharfe
2022-06-15 20:32 ` Ævar Arnfjörð Bjarmason
2022-06-16 18:55 ` René Scharfe
2022-06-24 11:13 ` Ævar Arnfjörð Bjarmason
2022-06-24 20:24 ` René Scharfe
2022-06-15 17:04 ` [PATCH v4 5/6] archive-tar: use OS_CODE 3 (Unix) for internal gzip René Scharfe
2022-06-15 17:05 ` [PATCH v4 6/6] archive-tar: use internal gzip by default René Scharfe
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