Re: [RFC][PATCH 00/13] percpu rwsem -v2
From: Peter Zijlstra
Date: Tue Jun 23 2015 - 10:34:29 EST
On Tue, Jun 23, 2015 at 11:35:24AM +0200, Daniel Wagner wrote:
> flock01
> mean variance sigma max min
> 4.1.0 11.7075 816.3341 28.5716 125.6552 0.0021
> 4.1.0+percpu-rwsem 11.4614 760.1345 27.5705 132.5030 0.0026
> tip 6.8390 329.3037 18.1467 81.0373 0.0021
> tip+percpu-rwsem 10.0870 546.7435 23.3825 106.2396 0.0026
> posix01
> mean variance sigma max min
> 4.1.0 121.9020 27882.5260 166.9806 603.5509 0.0063
> 4.1.0+percpu-rwsem 185.3981 38474.3836 196.1489 580.6532 0.0073
> tip 129.2736 23752.7122 154.1191 474.0604 0.0063
> tip+percpu-rwsem 142.6474 24732.1571 157.2646 468.7478 0.0072
Both these tests are incredibly unstable for me (as well as for you it
appears). Variance is through the roof on them.
I get runtimes like:
root@ivb-ex:/usr/local/src/lockperf# ./flock01 -n 240 -l 32 /tmp/a
0.266157011
root@ivb-ex:/usr/local/src/lockperf# ./flock01 -n 240 -l 32 /tmp/a
139.303399960
That's not really inspiring, if I use bigger loop counts it more or less
settles, but then the EX is unusable because it ends up running 3000
seconds per test.
In any case, on a smaller box (ivb-ep) I got the below results:
posix01
mean variance sigma max min
data-4.1.0-02756-ge3d06bd 250.7032 40.4864 6.3629 263.7736 238.5192
data-4.1.0-02756-ge3d06bd-dirty 252.6847 35.8953 5.9913 270.1679 233.0215
Which looks better, but the difference is still well within the variance
and thus not significant.
Lemme continue playing with this for a bit more.
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