From: Pete Wyckoff Date: Sun, 05 May 2013 15:40:01 GMT Subject: Re: "git grep" parallelism question Message-ID: <20130505154001.GA25257@padd.com> In-Reply-To: torvalds@linux-foundation.org wrote on Fri, 26 Apr 2013 13:31 -0700: > 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