Re: 2.6.4-mm2

[Mary Edie Meredith <maryedie@osdl.org>]

On Tue, 2004-03-23 at 11:32, Andrew Morton wrote:
> Mary Edie Meredith <maryedie@osdl.org> wrote:
> >
> > > 36% regression due to the CPU scheduler changes?  ow.
> >  > 
> >  > And that machine is a PIII, so presumably the setting of CONFIG_SCHED_SMT
> >  > makes no difference.
> >  > 
> >  > >From a quick look at the material you have there it appears that this
> >  > workload also is very I/O bound.  It's a little surprising that the CPU
> >  > scheduler could make so much difference.
> >  I'm not sure why you think this is IO bound. For 
> >  the throughput phase of the test (from which the 
> >  metric above is taken) there is very little physical 
> >  IO except at the start when the updates occur.  They
> >  finish in a few minutes, after which there is very
> >  little.
> > 
> >  http://khack.osdl.org/stp/290304/results/plot/thuput.vmstat_io.png
> >  http://khack.osdl.org/stp/290304/results/plot/thuput.vmstat.txt
> 
> There seems to be a large amount of idle time in the profiles and in the
> vmstat trace.
Yes.  There is considerably more idle time in the bad run:
Good one:
http://khack.osdl.org/stp/290298/results/plot/thuput.sar_cpu_all.png
Bad one:
http://khack.osdl.org/stp/290304/results/plot/thuput.sar_cpu_all.png

I am concerned with the drop in CPU utilization relative to
the other run.     

-- 
Mary Edie Meredith 
maryedie@osdl.org
503-626-2455 x42
Open Source Development Labs