Re: "git grep" parallelism question

From: Pete Wyckoff <pw@padd.com>
Date: May 5, 2013, 15:40 UTC
Message-ID: <20130505154001.GA25257@padd.com>
In-Reply-To: <CA+55aFx1t_MT+20Bbkse-wHeLz8E06yqaOhbb12GzHNDrE2tWA@mail.gmail.com>

torvalds@linux-foundation.org wrote on Fri, 26 Apr 2013 13:31 -0700:

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..

NFS numbers behave as expected:  IO concurrency is key.

WARM 1 real 0m23.147s 2 real 0m13.913s 4 real 0m6.958s 8 real 0m4.104s 16 real 0m3.588s 32 real 0m3.212s 64 real 0m3.173s

COLD 1 real 1m36.969s 2 real 0m51.627s 4 real 0m32.994s 8 real 0m25.657s 16 real 0m21.260s 32 real 0m18.138s 64 real 0m17.265s

I am tempted to change the default locally from 8 to 32.

		-- Pete