Re: [PATCH 06/17] sched/fair: Add lag based placement
From: Chen Yu
Date: Thu Apr 13 2023 - 11:43:53 EST
On 2023-04-05 at 11:47:20 +0200, Peter Zijlstra wrote:
> On Mon, Apr 03, 2023 at 05:18:06PM +0800, Chen Yu wrote:
> > On 2023-03-28 at 11:26:28 +0200, Peter Zijlstra wrote:
So I launched the test on another platform with more CPUs,
baseline: 6.3-rc6
compare: sched/eevdf branch on top of commit 8c59a975d5ee ("sched/eevdf: Debug / validation crud")
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schbench:mthreads = 2
baseline eevdf+NO_PLACE_BONUS
worker_threads
25% 80.00 +19.2% 95.40 schbench.latency_90%_us
(0.00%) (0.51%) stddev
50% 183.70 +2.2% 187.80 schbench.latency_90%_us
(0.35%) (0.46%) stddev
75% 4065 -21.4% 3193 schbench.latency_90%_us
(69.65%) (3.42%) stddev
100% 13696 -92.4% 1040 schbench.latency_90%_us
(5.25%) (69.03%) stddev
125% 16457 -78.6% 3514 schbench.latency_90%_us
(10.50%) (6.25%) stddev
150% 31177 -77.5% 7008 schbench.latency_90%_us
(6.84%) (5.19%) stddev
175% 40729 -75.1% 10160 schbench.latency_90%_us
(6.11%) (2.53%) stddev
200% 52224 -74.4% 13385 schbench.latency_90%_us
(10.42%) (1.72%) stddev
eevdf+NO_PLACE_BONUS eevdf+PLACE_BONUS
worker_threads
25% 96.30 +0.2% 96.50 schbench.latency_90%_us
(0.66%) (0.52%) stddev
50% 187.20 -3.0% 181.60 schbench.latency_90%_us
(0.21%) (0.71%) stddev
75% 3034 -84.1% 482.50 schbench.latency_90%_us
(5.56%) (27.40%) stddev
100% 648.20 +114.7% 1391 schbench.latency_90%_us
(64.70%) (10.05%) stddev
125% 3506 -3.0% 3400 schbench.latency_90%_us
(2.79%) (9.89%) stddev
150% 6793 +29.6% 8803 schbench.latency_90%_us
(1.39%) (7.30%) stddev
175% 9961 +9.2% 10876 schbench.latency_90%_us
(1.51%) (6.54%) stddev
200% 13660 +3.3% 14118 schbench.latency_90%_us
(1.38%) (6.02%) stddev
Summary for schbench: in most cases eevdf+NO_PLACE_BONUS gives the best performance.
And this is aligned with the previous test on another platform with smaller number of
CPUs, eevdf benefits schbench overall.
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hackbench: ipc=pipe mode=process default fd:20
baseline eevdf+NO_PLACE_BONUS
worker_threads
1 103103 -0.3% 102794 hackbench.throughput_avg
25% 115562 +825.7% 1069725 hackbench.throughput_avg
50% 296514 +352.1% 1340414 hackbench.throughput_avg
75% 498059 +190.8% 1448156 hackbench.throughput_avg
100% 804560 +74.8% 1406413 hackbench.throughput_avg
eevdf+NO_PLACE_BONUS eevdf+PLACE_BONUS
worker_threads
1 102172 +1.5% 103661 hackbench.throughput_avg
25% 1076503 -52.8% 508612 hackbench.throughput_avg
50% 1394311 -68.2% 443251 hackbench.throughput_avg
75% 1476502 -70.2% 440391 hackbench.throughput_avg
100% 1512706 -76.2% 359741 hackbench.throughput_avg
Summary for hackbench pipe process test: in most cases eevdf+NO_PLACE_BONUS gives the best performance.
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unixbench: test=pipe
baseline eevdf+NO_PLACE_BONUS
nr_task
1 1405 -0.5% 1398 unixbench.score
25% 77942 +0.9% 78680 unixbench.score
50% 155384 +1.1% 157100 unixbench.score
75% 179756 +0.3% 180295 unixbench.score
100% 204030 -0.2% 203540 unixbench.score
125% 204972 -0.4% 204062 unixbench.score
150% 205891 -0.5% 204792 unixbench.score
175% 207051 -0.5% 206047 unixbench.score
200% 209387 -0.9% 207559 unixbench.score
eevdf+NO_PLACE_BONUS eevdf+PLACE_BONUS
nr_task
1 1405 -0.3% 1401 unixbench.score
25% 78640 +0.0% 78647 unixbench.score
50% 157153 -0.0% 157093 unixbench.score
75% 180152 +0.0% 180205 unixbench.score
100% 203479 -0.0% 203464 unixbench.score
125% 203866 +0.1% 204013 unixbench.score
150% 204872 -0.0% 204838 unixbench.score
175% 205799 +0.0% 205824 unixbench.score
200% 207152 +0.2% 207546 unixbench.score
Seems to have no impact on unixbench in pipe mode.
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netperf: TCP_RR, ipv4, loopback
baseline eevdf+NO_PLACE_BONUS
nr_threads
25% 56232 -1.7% 55265 netperf.Throughput_tps
50% 49876 -3.1% 48338 netperf.Throughput_tps
75% 24281 +1.9% 24741 netperf.Throughput_tps
100% 73598 +3.8% 76375 netperf.Throughput_tps
125% 59119 +1.4% 59968 netperf.Throughput_tps
150% 49124 +1.2% 49727 netperf.Throughput_tps
175% 41929 +0.2% 42004 netperf.Throughput_tps
200% 36543 +0.4% 36677 netperf.Throughput_tps
eevdf+NO_PLACE_BONUS eevdf+PLACE_BONUS
nr_threads
25% 55296 +4.7% 57877 netperf.Throughput_tps
50% 48659 +1.9% 49585 netperf.Throughput_tps
75% 24741 +0.3% 24807 netperf.Throughput_tps
100% 76455 +6.7% 81548 netperf.Throughput_tps
125% 60082 +7.6% 64622 netperf.Throughput_tps
150% 49618 +7.7% 53429 netperf.Throughput_tps
175% 41974 +7.6% 45160 netperf.Throughput_tps
200% 36677 +6.5% 39067 netperf.Throughput_tps
Seems to have no impact on netperf.
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stress-ng: futex
baseline eevdf+NO_PLACE_BONUS
nr_threads
25% 207926 -21.0% 164356 stress-ng.futex.ops_per_sec
50% 46611 -16.1% 39130 stress-ng.futex.ops_per_sec
75% 71381 -11.3% 63283 stress-ng.futex.ops_per_sec
100% 58766 -0.8% 58269 stress-ng.futex.ops_per_sec
125% 59859 +11.3% 66645 stress-ng.futex.ops_per_sec
150% 52869 +7.6% 56863 stress-ng.futex.ops_per_sec
175% 49607 +22.9% 60969 stress-ng.futex.ops_per_sec
200% 56011 +11.8% 62631 stress-ng.futex.ops_per_sec
When the system is not busy, there is regression. When the system gets busier,
there are some improvement. Even with PLACE_BONUS enabled, there are still regression.
Per the perf profile of 50% case, there are nearly the same ratio of wakeup with vs without
eevdf patch applied:
50.82 -0.7 50.15 perf-profile.children.cycles-pp.futex_wake
but there are more preemption after eevdf enabled:
135095 +15.4% 155943 stress-ng.time.involuntary_context_switches
which is near the performance loss -16.1%
That is to say, eevdf help futex wakee grab the CPU easier(benefit latency), while might
have some impact on throughput?
thanks,
Chenyu