On Thu, Jul 31, 2014 at 12:42:41PM +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
Yes, they are.
It means, for commit ebe06187bf2aec1, the number for
num_hint_local_faults is 94500 for ivb42 machine and 67745 for lkp-snb01
machine. The 3%, 4% following that number means the deviation of the
different runs to their average(we usually run it multiple times to
phase out possible sharp values). We should probably remove that
percentage, as they cause confusion if no detailed explanation and may
not mean much to the commit author and others(if the deviation is big
enough, we should simply drop that result).
The percentage in the middle is the change between the two commits.
Another thing is the meaning of the numbers, it doesn't seem that
evident they are for proc-vmstat.numa_hint_faults_local. Maybe something
like this is better?
ebe06187bf2aec1 a43455a1d572daf7b730fe12e proc-vmstat.numa_hint_faults_local
--------------- ------------------------- -----------------------------
94500 +115.6% 203711 ivb42/hackbench/50%-threads-pipe
67745 +64.1% 111174
lkp-snb01/hackbench/50%-threads-socket
162245 +94.1% 314885 TOTAL
Regards,
Aaron
> 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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