Re: sysbench throughput degradation in 4.13+

Matt Fleming
2017-10-06T10:37:26Z

On Wed, 04 Oct, at 06:18:50PM, Peter Zijlstra wrote:
> On Tue, Oct 03, 2017 at 10:39:32AM +0200, Peter Zijlstra wrote:
> > So I was waiting for Rik, who promised to run a bunch of NUMA workloads
> > over the weekend.
> >
> > The trivial thing regresses a wee bit on the overloaded case, I've not
> > yet tried to fix it.
>
> WA_IDLE is my 'old' patch and what you all tested, WA_WEIGHT is the
> addition -- based on the old scheme -- that I've tried in order to lift
> the overloaded case (including hackbench).

My results (2 nodes, 12 cores/node, 2 threads/core) show that you've
pretty much restored hackbench performance to v4.12. However, it's a
regression against v4.13 for hackbench-process-pipes (I'm guessing the
v4.13 improvement is due to Rik's original patches).

The last two result columns are your latest patch with NO_WA_WEIGHT
and then with WA_WEIGHT enabled.

(I hope you've all got wide terminals)

hackbench-process-pipes
4.12.0 4.13.0 4.13.0 4.13.0 4.13.0 4.13.0
vanilla vanilla peterz-fix rik-fixpeterz-fix-v2-no-wa-weightpeterz-fix-v2-wa-weight
Amean 1 1.1600 ( 0.00%) 1.6037 ( -38.25%) 1.0727 ( 7.53%) 1.0200 ( 12.07%) 1.0837 ( 6.58%) 1.1110 ( 4.22%)
Amean 4 2.4207 ( 0.00%) 2.2300 ( 7.88%) 2.0520 ( 15.23%) 1.9483 ( 19.51%) 2.0623 ( 14.80%) 2.2807 ( 5.78%)
Amean 7 5.4140 ( 0.00%) 3.2027 ( 40.84%) 3.6100 ( 33.32%) 3.5620 ( 34.21%) 3.5590 ( 34.26%) 4.6573 ( 13.98%)
Amean 12 9.7130 ( 0.00%) 4.7170 ( 51.44%) 6.5280 ( 32.79%) 6.2063 ( 36.10%) 6.5670 ( 32.39%) 10.5440 ( -8.56%)
Amean 21 11.6687 ( 0.00%) 8.8073 ( 24.52%) 14.4997 ( -24.26%) 10.2700 ( 11.99%) 14.3187 ( -22.71%) 11.5417 ( 1.09%)
Amean 30 14.6410 ( 0.00%) 11.7003 ( 20.09%) 23.7660 ( -62.32%) 13.9847 ( 4.48%) 21.8957 ( -49.55%) 14.4847 ( 1.07%)
Amean 48 19.8780 ( 0.00%) 17.0317 ( 14.32%) 37.6397 ( -89.35%) 19.7577 ( 0.61%) 39.2110 ( -97.26%) 20.3293 ( -2.27%)
Amean 79 46.4200 ( 0.00%) 27.1180 ( 41.58%) 58.4037 ( -25.82%) 35.5537 ( 23.41%) 60.8957 ( -31.18%) 49.7470 ( -7.17%)
Amean 110 57.7550 ( 0.00%) 42.7013 ( 26.06%) 73.0483 ( -26.48%) 48.8880 ( 15.35%) 77.8597 ( -34.81%) 61.9353 ( -7.24%)
Amean 141 61.0490 ( 0.00%) 48.0857 ( 21.23%) 98.5567 ( -61.44%) 63.2187 ( -3.55%) 90.4857 ( -48.22%) 68.3100 ( -11.89%)
Amean 172 70.5180 ( 0.00%) 59.3620 ( 15.82%) 122.5423 ( -73.77%) 76.0197 ( -7.80%) 127.4023 ( -80.67%) 75.8233 ( -7.52%)
Amean 192 76.1643 ( 0.00%) 65.1613 ( 14.45%) 142.1393 ( -86.62%) 91.4923 ( -20.12%) 145.0663 ( -90.46%) 80.5867 ( -5.81%)

But things look pretty good for hackbench-process-sockets:

hackbench-process-sockets
4.12.0 4.13.0 4.13.0 4.13.0 4.13.0 4.13.0
vanilla vanilla peterz-fix rik-fixpeterz-fix-v2-no-wa-weightpeterz-fix-v2-wa-weight
Amean 1 0.9657 ( 0.00%) 1.0850 ( -12.36%) 1.3737 ( -42.25%) 1.3093 ( -35.59%) 1.3220 ( -36.90%) 1.3937 ( -44.32%)
Amean 4 2.3040 ( 0.00%) 3.3840 ( -46.88%) 2.1807 ( 5.35%) 2.3010 ( 0.13%) 2.2070 ( 4.21%) 2.1770 ( 5.51%)
Amean 7 4.5467 ( 0.00%) 4.0787 ( 10.29%) 5.0530 ( -11.14%) 3.7427 ( 17.68%) 4.5517 ( -0.11%) 3.8560 ( 15.19%)
Amean 12 5.7707 ( 0.00%) 5.4440 ( 5.66%) 10.5680 ( -83.13%) 7.7240 ( -33.85%) 10.5990 ( -83.67%) 5.9123 ( -2.45%)
Amean 21 8.9387 ( 0.00%) 9.5850 ( -7.23%) 18.3103 (-104.84%) 10.9253 ( -22.23%) 18.1540 (-103.10%) 9.2627 ( -3.62%)
Amean 30 13.1243 ( 0.00%) 14.0773 ( -7.26%) 25.6563 ( -95.49%) 15.7590 ( -20.07%) 25.6920 ( -95.76%) 14.6523 ( -11.64%)
Amean 48 25.1030 ( 0.00%) 22.5233 ( 10.28%) 40.5937 ( -61.71%) 24.6727 ( 1.71%) 40.6357 ( -61.88%) 22.1807 ( 11.64%)
Amean 79 39.9150 ( 0.00%) 33.4220 ( 16.27%) 66.3343 ( -66.19%) 40.2713 ( -0.89%) 65.8543 ( -64.99%) 35.3360 ( 11.47%)
Amean 110 49.1700 ( 0.00%) 46.1173 ( 6.21%) 92.3153 ( -87.75%) 55.6567 ( -13.19%) 92.0567 ( -87.22%) 46.7280 ( 4.97%)
Amean 141 59.3157 ( 0.00%) 57.2670 ( 3.45%) 118.5863 ( -99.92%) 70.4800 ( -18.82%) 118.6013 ( -99.95%) 57.8247 ( 2.51%)
Amean 172 69.8163 ( 0.00%) 68.2817 ( 2.20%) 145.7583 (-108.77%) 83.0167 ( -18.91%) 144.4477 (-106.90%) 68.4457 ( 1.96%)
Amean 192 75.9913 ( 0.00%) 76.0503 ( -0.08%) 159.8487 (-110.35%) 91.0133 ( -19.77%) 159.6793 (-110.13%) 76.2690 ( -0.37%)

It's a similar story for hackbench-threads-{pipes,sockets}, i.e. pipes
regress but performance is restored for sockets.

Of course, like a dope, I forgot to re-run netperf with your WA_WEIGHT
patch. So I've queued that up now and it should be done by tomorrow.