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Re: "git grep" parallelism question

From
Thomas Rast <trast@inf.ethz.ch>
Date
Apr 27, 2013, 13:46 UTC
Message-ID
<87mwskf5nj.fsf@hexa.v.cablecom.net>
In-Reply-To
<CA+55aFx1t_MT+20Bbkse-wHeLz8E06yqaOhbb12GzHNDrE2tWA@mail.gmail.com>
Linus Torvalds <torvalds@linux-foundation.org> writes:
Show 5 quoted lines
> 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
Previous: Linus TorvaldsNext: Ramkumar Ramachandra
Message 6 of 16 in “"git grep" parallelism question”
  1. Linus TorvaldsApr 26, 2013
  2. Junio C HamanoApr 26, 2013
  3. Linus TorvaldsApr 26, 2013
  4. Junio C HamanoApr 26, 2013
  5. Linus TorvaldsApr 26, 2013
  6. Thomas RastApr 27, 2013
  7. Ramkumar RamachandraApr 29, 2013
  8. John KeepingApr 29, 2013
  9. Thomas RastApr 29, 2013
  10. John KeepingApr 29, 2013
  11. Junio C HamanoApr 29, 2013
  12. John KeepingApr 30, 2013
  13. Jeff KingApr 30, 2013
  14. John KeepingApr 30, 2013
  15. Jeff KingApr 30, 2013
  16. Pete WyckoffMay 5, 2013

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