Re: -mm seems significanty slower than mainline on kernbench

[Peter Williams <pwil3058@bigpond.net.au>]

Peter Williams wrote:
> Martin Bligh wrote:
>
> > > Thanks and looks like the results are in from 2.6.14-rc2-mm1 with the 
> > > patch backed out.
> > >
> > > Drumroll....
> > >
> > > http://test.kernel.org/perf/kernbench.moe.png
> > >
> > > The performance goes back to a range similar to 2.6.14-rc1-mm1 (see 
> > > 2.6.14-rc2-mm1 + 20328 in blue). Unfortunately this does implicate 
> > > this patch. Can we put it back into -mm only and allow Peter's 
> > > tweaks/fixes to go on top and have it tested some more before going 
> > > upstream?
> >
> >
> >
> > Hmm. Looks like we didn't get this as fixed up as I thought. Moe seems 
> > to be fixed (16x NUMA-Q), but elm3b132 is not (it's 4x, flat SMP ia32).
> > Look at the latest graphs ....
> >
> > Is it possible it only got fixed for NUMA boxes?
>
>
> It should be totally independent.
>
> But anyhow, I can't see the problem.  The only numbers that I can see 
> for 2.6.16-rc1-mm[1|2] (which are the ones with the latest fix) on this 
> graph are approx. 101 which is much the same as the best of the rest. Or 
> have I missed something?

Oops.  I was looking at the graphs for Moe but 
<http://test.kernel.org/perf/dbench.elm3b132.png> doesn't appear to be 
demonstrating a problem either.  Given the fluctuation in the 2.6.16-rc1 
results (235, 234, 211, 228.5 and 237.5), the results for 2.6.16-rc1-mm1 
(229) and 2.6.16-mm2 (219) aren't significantly different.

Peter
PS I have a modification for kernbench that calculates and displays the 
standard deviations for the various averages if you're interested.  This 
would enable you to display 95% (say) confidence bars on the graphed 
results which in turn makes it easier to spot significant differences.
--
Peter Williams                                   pwil3058@bigpond.net.au

"Learning, n. The kind of ignorance distinguishing the studious."
 -- Ambrose Bierce
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