On Thu, 2014-07-31 at 12:42 +0200, Peter Zijlstra wrote:
> On Tue, Jul 29, 2014 at 02:39:40AM -0400, Rik van Riel wrote:
> > On Tue, 29 Jul 2014 13:24:05 +0800
> > Aaron Lu <aaron...@intel.com> wrote:
> >
> > > FYI, we noticed the below changes on
> > >
> > > git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> > > commit a43455a1d572daf7b730fe12eb747d1e17411365 ("sched/numa: Ensure
> > > task_numa_migrate() checks the preferred node")
> > >
> > > ebe06187bf2aec1 a43455a1d572daf7b730fe12e
> > > --------------- -------------------------
> > > 94500 ~ 3% +115.6% 203711 ~ 6%
> > > ivb42/hackbench/50%-threads-pipe
> > > 67745 ~ 4% +64.1% 111174 ~ 5%
> > > lkp-snb01/hackbench/50%-threads-socket
> > > 162245 ~ 3% +94.1% 314885 ~ 6% TOTAL
> > > proc-vmstat.numa_hint_faults_local
> >
> > Hi Aaron,
> >
> > Jirka Hladky has reported a regression with that changeset as
> > well, and I have already spent some time debugging the issue.
>
> So assuming those numbers above are the difference in
> numa_hint_local_faults, the report is actually a significant
> _improvement_, not a regression.
>
> On my IVB-EP I get similar numbers; using:
>
> PRE=`grep numa_hint_faults_local /proc/vmstat | cut -d' ' -f2`
> perf bench sched messaging -g 24 -t -p -l 60000
> POST=`grep numa_hint_faults_local /proc/vmstat | cut -d' ' -f2`
> echo $((POST-PRE))
>
>
> tip/mater+origin/master tip/master+origin/master-a43455a1d57
>
> local total local total
> faults time faults time
>
> 19971 51.384 10104 50.838
> 17193 50.564 9116 50.208
> 13435 49.057 8332 51.344
> 23794 50.795 9954 51.364
> 20255 49.463 9598 51.258
>
> 18929.6 50.2526 9420.8 51.0024
> 3863.61 0.96 717.78 0.49
>
> So that patch improves both local faults and runtime. Its good (even
> though for the runtime we're still inside stdev overlap, so ideally I'd
> do more runs).
>
>
> Now I also did a run with the proposed patch, NUMA_SCALE/8 variant, and
> that slightly reduces both again:
>
> tip/master+origin/master+patch
>
> local total
> faults time
>
> 21296 50.541
> 12771 50.54
> 13872 52.224
> 23352 50.85
> 16516 50.705
>
> 17561.4 50.972
> 4613.32 0.71
>
> So for hackbench a43455a1d57 is good and the proposed patch is making
> things worse.
It also seems to be the case on a 8-socket 80 core DL980:
tip/master baseline:
67276 169.590 [sec]
82400 188.406 [sec]
87827 201.122 [sec]
96659 228.243 [sec]
83180 192.422 [sec]
tip/master + a43455a1d57 reverted
36686 170.373 [sec]
52670 187.904 [sec]
55723 203.597 [sec]
41780 174.354 [sec]
36070 173.179 [sec]
Runtimes are pretty much all over the place, cannot really say if it's
gotten slower or faster. However, on avg, we nearly double the amount of
hint local faults with the commit in question.
After adding the proposed fix (NUMA_SCALE/8 variant), it goes down
again, closer to without a43455a1d57"
tip/master + patch
50591 175.272 [sec]
57858 191.969 [sec]
77564 215.429 [sec]
50613 179.384 [sec]
61673 201.694 [sec]
> Let me see if I can still find my SPECjbb2005 copy to see what that
> does.
I'll try to dig it up as well.
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