Re: [patch v2 1/2] sched: check for prev_cpu == this_cpu beforecalling wake_affine()

From: Mike Galbraith
Date: Thu Apr 15 2010 - 01:17:33 EST


On Wed, 2010-04-14 at 13:45 -0700, Suresh Siddha wrote:
> On Thu, 2010-04-01 at 23:20 -0700, Mike Galbraith wrote:
> > Do you have a compute load bouncing painfully which this patch cures?
> >
> > I have no strong objections, and the result is certainly easier on the
> > eye. If I were making the decision, I'd want to see some numbers.
>
> Mike, PeterZ,
>
> Finally got sometime to get back to this and provide some data backing
> up my patch under discussion. Here are my test results:
>
> System is a two socket quad-core NHM-EP with SMT enabled and the
> workload is specjbb2005.
>
> Warehouses Throughput
> tip tip+proposed-fix
> 1 35142 35027
> 2 73563 75977
> 3 105806 109836
> 4 133421 142490
> 5 152151 168888
> 6 164936 195392
> 7 184763 208155
> 8 192419 223846
>
> PeterZ, I think the above clearly shows that we have a problem with the
> current -tip code. Please consider the proposed patch (which can be
> found at http://marc.info/?l=linux-kernel&m=127007936408754&w=2)
>
> Mike, with the above data, can I have your Ack for the patch?

Sure (not that you need it). A bit of abbreviated testing this morning
showed no big hairy differences. A bit of loss to very fast switchers,
but OTOH it improved ramp a bit for mysql/pgsql+oltp.

tip = v2.6.34-rc4-937-gba0b2c9
tip-x = tip + your patches

netperf TCP_RR
unpinned
tip 102877.39 102860.66 103210.25 avg 102982.76 1.000
tip-x 100926.59 100380.26 100536.35 avg 100614.40 .977

pinned
tip 100181.70 100288.34 99711.16 avg 100060.40 1.000
tip-x 99347.12 100551.80 99827.22 avg 99908.71 .998

tbench 8
tip 1195.51 1194.49 1197.46 avg 1195.82 1.000
tip-x 1183.19 1188.00 1188.13 avg 1186.44 .992

mysql+oltp
clients 1 2 4 8 16 32 64 128 256
tip 10424.24 20417.42 37151.84 36777.79 36442.06 36122.14 33803.15 30109.81 28368.75
11196.80 20443.43 37560.39 37358.14 36822.26 36132.95 34411.88 30349.47 28909.04
11204.02 20513.21 37550.11 37219.52 36840.44 36150.47 34445.02 30975.95 28840.59
tip avg 10941.68 20458.02 37420.78 37118.48 36701.58 36135.18 34220.01 30478.41 28706.12

tip-x 10331.62 20981.89 36768.45 36556.19 36069.56 35612.24 34100.70 30459.80 29043.76
11101.77 21153.77 37622.83 37228.68 36845.37 36256.04 34606.37 31287.36 28635.98
11076.66 21153.41 37703.80 37242.89 36842.93 36296.27 34733.06 30578.00 29313.10
tip-x avg 10836.68 21096.35 37365.02 37009.25 36585.95 36054.85 34480.04 30775.05 28997.61
vs tip .990 1.031 .998 .997 .996 .997 1.007 1.009 1.010

pgsql+oltp
clients 1 2 4 8 16 32 64 128 256
tip 14683.30 30452.18 53826.68 53793.77 52931.67 51959.47 51326.82 49205.13 46884.50
16154.17 30811.46 54277.20 53916.07 52792.89 52031.80 50967.99 48757.04 46259.84
16151.36 29913.89 54071.21 53499.94 52707.50 51867.73 50887.40 49310.96 46544.42
tip avg 15662.94 30392.51 54058.36 53736.59 52810.68 51953.00 51060.73 49091.04 46562.92

tip-x 14641.30 31402.11 54267.43 53835.83 53024.57 51992.08 50336.10 49083.58 46662.24
16167.44 31427.53 54008.47 53685.56 52709.81 52131.85 50848.08 48824.32 45973.29
16259.76 31381.42 54327.51 53791.91 52857.70 51912.42 50941.33 49028.19 45938.22
tip-x avg 15689.50 31403.68 54201.13 53771.10 52864.02 52012.11 50708.50 48978.69 46191.25
vs tip 1.001 1.033 1.002 1.000 1.001 1.001 .993 .997 .992


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