Re: [RFC PATCH v4 00/19] Core scheduling v4

Li, Aubrey
2019-10-31T11:42:58Z

On 2019/10/31 2:33, Vineeth Remanan Pillai wrote:
> Fourth iteration of the Core-Scheduling feature.
>
> This version was aiming mostly at addressing the vruntime comparison
> issues with v3. The main issue seen in v3 was the starvation of
> interactive tasks when competing with cpu intensive tasks. This issue
> is mitigated to a large extent.
>
> We have tested and verified that incompatible processes are not
> selected during schedule. In terms of performance, the impact
> depends on the workload:
> - on CPU intensive applications that use all the logical CPUs with
> SMT enabled, enabling core scheduling performs better than nosmt.
> - on mixed workloads with considerable io compared to cpu usage,
> nosmt seems to perform better than core scheduling.
>
> v4 is rebased on top of 5.3.5(dc073f193b70):
> https://github.com/digitalocean/linux-coresched/tree/coresched/v4-v5.3.5

Thanks to post V4 out. Refresh the data on my side. Since we have played
with Aaron's core vruntime patch for a while, no surprise in the result.

Thanks,
-Aubrey

Environment setup
--------------------------
Skylake 8170 server, 2 NUMA nodes, 52 cores, 104 CPUs (HT on)

Case 1:
-------
cgroup1 workload, sysbench CPU mode (non AVX workload)
cgroup2 workload, gemmbench (AVX512 workload)

sysbench throughput result:
.--------------------------------------------------------------------------------------------------------------------------------------.
|NA/AVX vanilla-SMT [std% / sem%] cpu% |coresched-SMT [std% / sem%] +/- cpu% | no-SMT [std% / sem%] +/- cpu% |
|--------------------------------------------------------------------------------------------------------------------------------------|
| 1/1 1269.1 [ 0.1%/ 0.0%] 1.9% | 1272.4 [ 0.1%/ 0.0%] 0.3% 1.9% | 1272.0 [ 0.1%/ 0.0%] 0.2% 3.9% |
| 2/2 2466.9 [ 0.6%/ 0.1%] 3.9% | 2534.2 [ 0.6%/ 0.1%] 2.7% 3.8% | 2511.9 [ 0.2%/ 0.0%] 1.8% 7.7% |
| 4/4 4725.2 [ 0.3%/ 0.0%] 7.7% | 4806.3 [ 0.2%/ 0.0%] 1.7% 7.7% | 4786.7 [ 0.9%/ 0.1%] 1.3% 14.6% |
| 8/8 9353.4 [ 0.1%/ 0.0%] 14.6% | 9357.4 [ 0.1%/ 0.0%] 0.0% 14.6% | 9352.3 [ 0.1%/ 0.0%] -0.0% 30.0% |
| 16/16 17543.1 [ 1.0%/ 0.1%] 30.1% | 18120.7 [ 0.2%/ 0.0%] 3.3% 30.1% | 17864.8 [ 1.2%/ 0.1%] 1.8% 60.1% |
| 32/32 26968.8 [ 3.9%/ 0.4%] 60.1% | 29448.9 [ 3.5%/ 0.3%] 9.2% 59.9% | 25308.1 [10.7%/ 0.9%] -6.2% 97.7% |
| 48/48 30466.2 [10.4%/ 1.0%] 89.3% | 38624.4 [ 4.2%/ 0.4%] 26.8% 89.1% | 26891.2 [14.8%/ 1.0%] -11.7% 99.5% |
| 64/64 37909.3 [11.1%/ 1.1%] 97.7% | 41671.7 [ 8.7%/ 0.9%] 9.9% 97.6% | 25898.3 [16.2%/ 1.0%] -31.7% 100.0% |
|128/128 39479.4 [24.6%/ 2.5%] 100.0% | 42119.6 [ 6.3%/ 0.6%] 6.7% 99.5% | 26830.1 [16.5%/ 1.1%] -32.0% 100.0% |
|256/256 42602.1 [16.4%/ 1.6%] 100.0% | 40041.3 [ 7.0%/ 0.7%] -6.0% 99.7% | 27634.7 [15.4%/ 1.1%] -35.1% 100.0% |
'--------------------------------------------------------------------------------------------------------------------------------------'

Case 2
------
cgroup1 workload, sysbench MySQL (non AVX workload)
cgroup2 workload, gemmbench (AVX512 workload)

sysbench throughput result:
.--------------------------------------------------------------------------------------------------------------------------------------.
|NA/AVX vanilla-SMT [std% / sem%] cpu% |coresched-SMT [std% / sem%] +/- cpu% | no-SMT [std% / sem%] +/- cpu% |
|--------------------------------------------------------------------------------------------------------------------------------------|
| 1/1 1018.2 [ 1.0%/ 0.1%] 1.9% | 915.8 [ 0.9%/ 0.1%] -10.1% 1.9% | 994.0 [ 1.4%/ 0.2%] -2.4% 3.9% |
| 2/2 1941.2 [ 0.7%/ 0.1%] 3.9% | 1746.0 [ 0.5%/ 0.1%] -10.1% 3.9% | 1946.2 [ 0.8%/ 0.1%] 0.3% 7.8% |
| 4/4 3763.9 [ 0.5%/ 0.0%] 7.8% | 3426.0 [ 1.5%/ 0.2%] -9.0% 7.8% | 3745.1 [ 1.1%/ 0.1%] -0.5% 15.6% |
| 8/8 7375.5 [ 1.3%/ 0.1%] 15.5% | 6647.1 [ 1.1%/ 0.1%] -9.9% 16.1% | 7368.4 [ 0.8%/ 0.1%] -0.1% 31.1% |
| 16/16 12990.3 [ 0.6%/ 0.1%] 31.1% | 10903.7 [ 1.9%/ 0.2%] -16.1% 32.0% | 12082.6 [ 4.7%/ 0.5%] -7.0% 62.9% |
| 32/32 18238.1 [ 6.1%/ 0.6%] 62.1% | 16580.8 [ 3.0%/ 0.3%] -9.1% 62.8% | 21193.6 [ 4.9%/ 0.6%] 16.2% 97.8% |
| 48/48 21708.6 [ 8.3%/ 0.8%] 90.3% | 17064.1 [ 9.5%/ 0.9%] -21.4% 90.4% | 18531.4 [16.6%/ 1.8%] -14.6% 99.5% |
| 64/64 18636.9 [13.1%/ 1.3%] 97.9% | 12376.1 [20.9%/ 2.1%] -33.6% 96.8% | 20025.8 [14.9%/ 2.4%] 7.5% 100.0% |
|128/128 16204.2 [16.8%/ 1.7%] 99.4% | 3776.1 [88.7%/ 8.9%] -76.7% 97.6% | 20263.5 [12.7%/ 6.8%] 25.1% 100.0% |
|256/256 16730.5 [17.9%/ 1.8%] 98.9% | 1499.7 [210.3%/21.0%] -91.0% 98.4% | 17633.1 [ 7.5%/ 8.9%] 5.4% 100.0% |
'--------------------------------------------------------------------------------------------------------------------------------------'

And for this case, we care about sysbench MySQL latency(ms):
.--------------------------------------------------------------------------------------------------------------------------------------.
|NA/AVX vanilla-SMT [std% / sem%] cpu% |coresched-SMT [std% / sem%] +/- cpu% | no-SMT [std% / sem%] +/- cpu% |
|--------------------------------------------------------------------------------------------------------------------------------------|
| 1/1 1.1 [ 3.7%/ 0.4%] 1.9% | 1.1 [ 1.0%/ 0.1%] -8.9% 1.9% | 1.1 [ 4.1%/ 0.4%] -2.0% 3.9% |
| 2/2 1.1 [ 0.7%/ 0.1%] 3.9% | 1.2 [ 0.8%/ 0.1%] -10.8% 3.9% | 1.1 [ 0.8%/ 0.1%] 0.2% 7.8% |
| 4/4 1.1 [ 0.7%/ 0.1%] 7.8% | 1.3 [ 3.8%/ 0.4%] -11.8% 7.8% | 1.2 [ 2.2%/ 0.2%] -1.1% 15.6% |
| 8/8 1.2 [ 2.2%/ 0.2%] 15.5% | 1.3 [ 3.0%/ 0.3%] -11.7% 16.1% | 1.2 [ 1.8%/ 0.2%] 0.4% 31.1% |
| 16/16 1.4 [ 1.5%/ 0.1%] 31.1% | 2.0 [ 8.2%/ 0.8%] -45.8% 32.0% | 1.9 [18.2%/ 1.7%] -33.2% 62.9% |
| 32/32 2.4 [ 6.6%/ 0.7%] 62.1% | 2.6 [ 3.1%/ 0.3%] -6.2% 62.8% | 2.2 [23.5%/ 2.0%] 8.5% 97.8% |
| 48/48 2.7 [ 5.3%/ 0.5%] 90.3% | 3.4 [ 3.5%/ 0.4%] -26.1% 90.4% | 6.2 [19.3%/ 3.5%] -128.0% 99.5% |
| 64/64 5.9 [13.0%/ 1.3%] 97.9% | 8.3 [ 9.8%/ 1.0%] -40.1% 96.8% | 7.4 [16.6%/ 1.5%] -25.1% 100.0% |
|128/128 17.4 [46.8%/ 4.7%] 99.4% | 248.0 [146.9%/14.7%] -1327.8% 97.6% | 11.0 [10.5%/ 0.0%] 36.7% 100.0% |
|256/256 33.5 [67.1%/ 6.7%] 98.9% | 1279.5 [245.6%/24.6%] -3716.6% 98.4% | 21.5 [21.5%/ 0.0%] 36.0% 100.0% |
'--------------------------------------------------------------------------------------------------------------------------------------'

Note:
----
64/64: 64 sysbench threads(in one cgroup) and 64 gemmbench threads(in other cgroup) run simultaneously.
Vanilla-SMT: baseline with HT on
coresched-SMT: core scheduling enabled
no-SMT: HT off thru /sys/devices/system/cpu/smt/control
std%: standard deviation
sem%: standard error of the mean
±: improvement/regression against baseline
cpu%: derived by vmstat.idle and vmstat.iowait