Re: [RFC][PATCH 0/5] select_idle_sibling() wreckage

[Li, Aubrey]

Hi Peter,

On 2020/12/15 0:48, Peter Zijlstra wrote:
> Hai, here them patches Mel asked for. They've not (yet) been through the
> robots, so there might be some build fail for configs I've not used.
> 
> Benchmark time :-)
> 

Here is the data on my side, benchmarks were tested on a x86 4 sockets system
with 24 cores per socket and 2 hyperthreads per core, total 192 CPUs.

uperf throughput: netperf workload, tcp_nodelay, r/w size = 90

  threads	baseline-avg	%std	patch-avg	%std
  96		1		0.78	1.0072		1.09
  144		1		0.58	1.0204		0.83
  192		1		0.66	1.0151		0.52
  240		1		2.08	0.8990		0.75

hackbench: process mode, 25600 loops, 40 file descriptors per group

  group		baseline-avg	%std	patch-avg	%std
  2(80)		1		10.02	1.0339		9.94
  3(120)	1		6.69	1.0049		6.92
  4(160)	1		6.76	0.8663		8.74
  5(200)	1		2.96	0.9651		4.28

schbench: 99th percentile latency, 16 workers per message thread

  mthread	baseline-avg	%std	patch-avg	%std
  6(96)		1		0.88	1.0055		0.81
  9(144)	1		0.59	1.0007		0.37
  12(192)	1		0.61	0.9973		0.82
  15(240)	1		25.05	0.9251		18.36

sysbench mysql throughput: read/write, table size = 10,000,000

  thread	baseline-avg	%std	patch-avg	%std
  96		1               6.62	0.9668		4.04
  144		1		9.29	0.9579		6.53
  192		1		9.52	0.9503		5.35
  240		1		8.55	0.9657		3.34

It looks like 
- hackbench has a significant improvement of 4 groups
- uperf has a significant regression of 240 threads

Please let me know if you have any interested cases I can run/rerun.

Thanks,
-Aubrey