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. Let me see if I can still find my SPECjbb2005 copy to see what that does.
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