From: Thomas Rast <trast@inf•ethz.ch>
To: Linus Torvalds <torvalds@linux-foundation•org>
Cc: "Junio C Hamano" <gitster@pobox•com>,
"Git Mailing List" <git@vger•kernel.org>,
"Nguyễn Thái Ngọc Duy" <pclouds@gmail•com>
Subject: Re: "git grep" parallelism question
Date: Sat, 27 Apr 2013 15:46:08 +0200 [thread overview]
Message-ID: <87mwskf5nj.fsf@hexa.v.cablecom.net> (raw)
In-Reply-To: <CA+55aFx1t_MT+20Bbkse-wHeLz8E06yqaOhbb12GzHNDrE2tWA@mail.gmail.com> (Linus Torvalds's message of "Fri, 26 Apr 2013 13:31:41 -0700")
Linus Torvalds <torvalds@linux-foundation•org> writes:
> Anyway, I think your patch is good if for no other reason that it
> allows this kind of testing, but at least for my machine, clearly the
> current default of eight threads is actually "good enough". Maybe
> somebody with a very different machine might want to run the above
> script and see if how sensitive other machines are to this parameter..
I think the last time Duy, Peff, me and others looked into grep
threading (which was a while ago) we basically reached the conclusion
that it's very unstable across machines.
Back then I tested things on a 2x6-core Xeon OS X machine and there the
performance (for the hot-cache, worktree case, which should parallelize
nicely) flatlines at 5 threads for no apparent reason.
--
Thomas Rast
trast@{inf,student}.ethz.ch
next prev parent reply other threads:[~2013-04-27 13:46 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-26 17:31 "git grep" parallelism question Linus Torvalds
2013-04-26 18:47 ` Junio C Hamano
2013-04-26 18:54 ` Linus Torvalds
2013-04-26 19:19 ` Junio C Hamano
2013-04-26 20:31 ` Linus Torvalds
2013-04-27 13:46 ` Thomas Rast [this message]
2013-04-29 14:05 ` Ramkumar Ramachandra
2013-04-29 16:18 ` John Keeping
2013-04-29 18:04 ` Thomas Rast
2013-04-29 18:08 ` John Keeping
2013-04-29 22:22 ` Junio C Hamano
2013-04-30 8:08 ` John Keeping
2013-04-30 15:59 ` Jeff King
2013-04-30 16:12 ` John Keeping
2013-04-30 16:14 ` Jeff King
2013-05-05 15:40 ` Pete Wyckoff
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