On Mon, Apr 28, 2014 at 10:39 AM, Stepan Kasal <ka...@ucw.cz> wrote: > From: theoleblond <theodore.lebl...@gmail.com> > Date: Wed, 16 May 2012 06:52:49 -0700 > > I played around with this quite a bit. After trying some more complex > schemes, I found that what worked best is to just sleep 1 millisecond > between iterations. Though it's a very short time, it still completely > eliminates the busy wait condition, without hurting perf. > > There code uses SleepEx(1, TRUE) to sleep. See this page for a good > discussion of why that is better than calling SwitchToThread, which > is what was used previously: > http://stackoverflow.com/questions/1383943/switchtothread-vs-sleep1 > > Note that calling SleepEx(0, TRUE) does *not* solve the busy wait. > > The most striking case was when testing on a UNC share with a large repo, > on a single CPU machine. Without the fix, it took 4 minutes 15 seconds, > and with the fix it took just 1:08! I think it's because git-upload-pack's > busy wait was eating the CPU away from the git process that's doing the > real work. With multi-proc, the timing is not much different, but tons of > CPU time is still wasted, which can be a killer on a server that needs to > do bunch of other things. > > I also tested the very fast local case, and didn't see any measurable > difference. On a big repo with 4500 files, the upload-pack took about 2 > seconds with and without the fix. > --- > > This is one of the patches that lives in msysGit, could it be > accepted upstream? > It modifies the Windows compat function only.
compat/poll/poll.c comes from Gnulib, so it would be better to submit the patch there and update. -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
