From: Thomas Rast Date: Sat, 27 Apr 2013 13:46:08 GMT Subject: Re: "git grep" parallelism question Message-ID: <87mwskf5nj.fsf@hexa.v.cablecom.net> In-Reply-To: Linus Torvalds 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