From: "Li, Aubrey" <aubrey.li@linux.intel.com>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>, Qais Yousef <qais.yousef@arm.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 0/5] Scan for an idle sibling in a single pass
Date: Mon, 25 Jan 2021 19:37:55 +0800 [thread overview]
Message-ID: <31300317-89e0-ca5e-d095-920c6cfe8704@linux.intel.com> (raw)
In-Reply-To: <20210125090419.GW3592@techsingularity.net>
On 2021/1/25 17:04, Mel Gorman wrote:
> On Mon, Jan 25, 2021 at 12:29:47PM +0800, Li, Aubrey wrote:
>>>>> hackbench -l 2560 -g 1 on 8 cores arm64
>>>>> v5.11-rc4 : 1.355 (+/- 7.96)
>>>>> + sis improvement : 1.923 (+/- 25%)
>>>>> + the patch below : 1.332 (+/- 4.95)
>>>>>
>>>>> hackbench -l 2560 -g 256 on 8 cores arm64
>>>>> v5.11-rc4 : 2.116 (+/- 4.62%)
>>>>> + sis improvement : 2.216 (+/- 3.84%)
>>>>> + the patch below : 2.113 (+/- 3.01%)
>>>>>
>>
>> 4 benchmarks reported out during weekend, with patch 3 on a x86 4s system
>> with 24 cores per socket and 2 HT per core, total 192 CPUs.
>>
>> It looks like mid-load has notable changes on my side:
>> - netperf 50% num of threads in TCP mode has 27.25% improved
>> - tbench 50% num of threads has 9.52% regression
>>
>
> It's interesting that patch 3 would make any difference on x64 given that
> it's SMT2. The scan depth should have been similar. It's somewhat expected
> that it will not be a universal win, particularly once the utilisation
> is high enough to spill over in sched domains (25%, 50%, 75% utilisation
> being interesting on 4-socket systems). In such cases, double scanning can
> still show improvements for workloads that idle rapidly like tbench and
> hackbench even though it's expensive. The extra scanning gives more time
> for a CPU to go idle enough to be selected which can improve throughput
> but at the cost of wake-up latency,
aha, sorry for the confusion. Since you and Vincent discussed to drop
patch3, I just mentioned I tested 5 patches with patch3, not patch3 alone.
>
> Hopefully v4 can be tested as well which is now just a single scan.
>
Sure, may I know the baseline of v4?
Thanks,
-Aubrey
next prev parent reply other threads:[~2021-01-26 5:54 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-19 11:22 [PATCH v3 0/5] Scan for an idle sibling in a single pass Mel Gorman
2021-01-19 11:22 ` [PATCH 1/5] sched/fair: Remove SIS_AVG_CPU Mel Gorman
2021-01-19 11:22 ` [PATCH 2/5] sched/fair: Move avg_scan_cost calculations under SIS_PROP Mel Gorman
2021-01-19 11:22 ` [PATCH 3/5] sched/fair: Make select_idle_cpu() proportional to cores Mel Gorman
2021-01-19 11:22 ` [PATCH 4/5] sched/fair: Remove select_idle_smt() Mel Gorman
2021-01-19 11:22 ` [PATCH 5/5] sched/fair: Merge select_idle_core/cpu() Mel Gorman
2021-01-20 8:30 ` Gautham R Shenoy
2021-01-20 9:12 ` Mel Gorman
2021-01-20 9:21 ` Vincent Guittot
2021-01-20 9:54 ` Mel Gorman
2021-01-20 9:58 ` Vincent Guittot
2021-01-20 13:55 ` Gautham R Shenoy
2021-01-19 11:33 ` [PATCH v3 0/5] Scan for an idle sibling in a single pass Vincent Guittot
2021-01-19 12:02 ` Mel Gorman
2021-01-22 9:30 ` Vincent Guittot
2021-01-22 10:14 ` Mel Gorman
2021-01-22 13:22 ` Vincent Guittot
2021-01-25 4:29 ` Li, Aubrey
2021-01-25 9:04 ` Mel Gorman
2021-01-25 11:37 ` Li, Aubrey [this message]
2021-01-25 11:46 ` Mel Gorman
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