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Message-ID: <51A7FA14.70902@intel.com>
Date: Fri, 31 May 2013 09:17:08 +0800
From: Alex Shi <alex.shi@...el.com>
To: Morten Rasmussen <morten.rasmussen@....com>
CC: peterz@...radead.org, mingo@...nel.org, preeti@...ux.vnet.ibm.com,
vincent.guittot@...aro.org, efault@....de, pjt@...gle.com,
linux-kernel@...r.kernel.org, linaro-kernel@...ts.linaro.org,
arjan@...ux.intel.com, len.brown@...el.com, corbet@....net,
tglx@...utronix.de
Subject: Re: [RFC] Comparison of power-efficient scheduling patch sets
On 05/30/2013 09:47 PM, Morten Rasmussen wrote:
> Hi,
>
> A number of patch sets related to power-efficient scheduling have been
> posted over the last couple of months. Most of them do not have much
> data to back them up, so I decided to do some testing.
>
> Common for all of the patch sets that I have tested, except one, is that
> they attempt to pack tasks on as few cpus as possible to allow the
> remaining cpus to enter deeper sleep states - a strategy that should
> make sense on most platforms that support per-cpu power gating and
> multi-socket machines.
>
> Kernel: 3.9
>
> Patch sets:
> rlb-v4: sched: use runnable load based balance (Alex Shi)
> <https://lkml.org/lkml/2013/4/27/13>
Thanks for the valuable comparison!
The runnable load balance target is performance. It is still try to
disperse tasks to as much as possible CPUs. :)
The latest v7 version remove the 6th patch(wake_affine change) in v4.
and plus fix a slept time double counting issue, and remove
blocked_load_avg in tg load.
http://comments.gmane.org/gmane.linux.kernel/1498988
Enjoy!
> pas-v7: sched: power aware scheduling (Alex Shi)
> <https://lkml.org/lkml/2013/4/3/732>
We still have some internal discussion on this patch set before update
it. Sorry for response late on this patchset!
> pst-v3: sched: packing small tasks (Vincent Guittot)
> <https://lkml.org/lkml/2013/3/22/183>
> pst-v4: sched: packing small tasks (Vincent Guittot)
> <https://lkml.org/lkml/2013/4/25/396>
>
> Configuration:
> pas-v7: Set to "powersaving" mode.
> pst-v4: Set to "Full" packing mode.
>
> Platform:
> ARM TC2 (test-chip), 2xCortex-A15 + 3xCortex-A7. Cortex-A15s disabled.
>
> Measurement technique:
> Time spent non-idle (not in idle state) for each cpu based on cpuidle
> ftrace events. TC2 does not have per-core power-gating, so packing
> inside the A7 cluster does not lead to any significant power savings.
> Note that any product grade hardware (TC2 is a test-chip) will very
> likely have per-core power-gating, so in those cases packing will have
> an appreciable effect on power savings.
> Measuring non-idle time rather than power should give a more clear idea
> about the effect of the patch sets given that the idle back-end is
> highly implementation specific.
>
> Benchmarks:
> audio playback (Android): 30s mp3 file playback on Android.
> bbench+audio (Android): Web page rendering while doing mp3 playback.
> andebench_native (Android): Android benchmark running in native mode.
> cyclictest: Short periodic tasks.
>
> Results:
> Two runs for each patch set.
>
> audio playback (Android) SMP
> non-idle % cpu 0 cpu 1 cpu 2
> 3.9_1 11.96 2.86 2.48
> 3.9_2 12.64 2.81 1.88
> rlb-v4_1 12.61 2.44 1.90
> rlb-v4_2 12.45 2.44 1.90
> pas-v7_1 16.17 0.03 0.24
> pas-v7_2 16.08 0.28 0.07
> pst-v3_1 15.18 2.76 1.70
> pst-v3_2 15.13 0.80 0.38
> pst-v4_1 16.14 0.05 0.00
> pst-v4_2 16.34 0.06 0.00
>
> bbench+audio (Android) SMP
> non-idle % cpu 0 cpu 1 cpu 2 render time
> 3.9_1 25.00 20.73 21.22 812
> 3.9_2 24.29 19.78 22.34 795
> rlb-v4_1 23.84 19.36 22.74 782
> rlb-v4_2 24.07 19.36 22.74 797
> pas-v7_1 28.29 17.86 16.01 869
> pas-v7_2 28.62 18.54 15.05 908
> pst-v3_1 29.14 20.59 21.72 830
> pst-v3_2 27.69 18.81 20.06 830
> pst-v4_1 42.20 13.63 2.29 880
> pst-v4_2 41.56 14.40 2.17 935
>
> andebench_native (8 threads) (Android) SMP
> non-idle % cpu 0 cpu 1 cpu 2 Score
> 3.9_1 99.22 98.88 99.61 4139
> 3.9_2 99.56 99.31 99.46 4148
> rlb-v4_1 99.49 99.61 99.53 4153
> rlb-v4_2 99.56 99.61 99.53 4149
> pas-v7_1 99.53 99.59 99.29 4149
> pas-v7_2 99.42 99.63 99.48 4150
> pst-v3_1 97.89 99.33 99.42 4097
> pst-v3_2 99.16 99.62 99.42 4097
> pst-v4_1 99.34 99.01 99.59 4146
> pst-v4_2 99.49 99.52 99.20 4146
>
> cyclictest SMP
> non-idle % cpu 0 cpu 1 cpu 2
> 3.9_1 9.13 8.88 8.41
> 3.9_2 10.27 8.02 6.30
> rlb-v4_1 8.88 8.09 8.11
> rlb-v4_2 8.49 8.09 8.11
> pas-v7_1 10.20 0.02 11.50
> pas-v7_2 7.86 14.31 0.02
> pst-v3_1 20.44 8.68 7.97
> pst-v3_2 20.41 0.78 1.00
> pst-v4_1 21.32 0.21 0.05
> pst-v4_2 21.56 0.21 0.04
>
> Overall, pas-v7 seems to do a fairly good job at packing. The idle time
> distribution seems to be somewhere between pst-v3 and the more
> aggressive pst-v4 for all the benchmarks. pst-v4 manages to keep two
> cpus nearly idle (<0.25% non-idle) for both cyclictest and audio, which
> is better than both pst-v3 and pas-v7. pas-v7 fails to pack cyclictest.
> Packing does come at at cost which can be seen for bbench+audio, where
> pst-v3 and rlb-v4 get better render times than pas-v7 and pst-v4 which
> do more aggressive packing. rlb-v4 does not pack, it is only included
> for reference.
>
> From a packing perspective pst-v4 seems to do the best job for the
> workloads that I have tested on ARM TC2. The less aggressive packing in
> pst-v3 may be a better choice for in terms of performance.
>
> I'm well aware that these tests are heavily focused on mobile workloads.
> I would therefore encourage people to share your test results for your
> workloads on your platforms to complete the picture. Comments are also
> welcome.
>
> Thanks,
> Morten
>
>
--
Thanks
Alex
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