On Jan 18, 2011, at 1:49 AM, Bolstridge, Andrew wrote: > Hi. > > Just a quick question/suggestion: > > If the exponential sleep can be a maximum of 25ms, and the random one > between 0 and 100ms, what is the performance like if you just sleep for > 25ms - without any randomness, or doubling of sleep times? > > I used to find (but this was ages ago) that just sleeping for 1ms would > force the CPU to carry on with other things, perhaps that would have an > effect that's just as good as the longer sleeps? > > Top stuff BTW, I doubt it'll have much effect on my slow virtual machine > disks, but every performance boost helps! > Thanks.
[cc'ing [email protected]] If you're not storing your repositories on NFS, then this patch doesn't help performance, the kernel's fcntl() will block the caller and unblock it when the lock is released. The sleeps are there to not pound the NFS server with traffic. I pt in a fixed 25ms sleep and here are the results, which don't look as good as the random sleep: N is 1567 sum is 806.845106840133 mean is 0.514897962246415 SD N is 0.591845693041212 SD N-1 is 0.592034630218584 min is 0.1712911129 25% is 0.232829093933 50% is 0.273239135742 90% is 1.02276110649 95% is 1.61777615547 99% is 3.28569889069 max is 6.39945292473 Percentage of commits by slow systems: 27.1 Percentage of commits by fast systems: 72.9 Blair
