Re: [BENCHMARK] 2.5.39-mm1

From: Con Kolivas (conman@kolivas.net)
Date: Tue Oct 01 2002 - 07:19:21 EST


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On Tuesday 01 Oct 2002 8:20 pm, Andrew Morton wrote:
> Jens Axboe wrote:
> > On Mon, Sep 30 2002, Andrew Morton wrote:
> > > > io_load:
> > > > Kernel Time CPU Ratio
> > > > 2.4.19 216.05 33% 3.19
> > > > 2.5.38 887.76 8% 13.11
> > > > 2.5.38-mm3 105.17 70% 1.55
> > > > 2.5.39 229.4 34% 3.4
> > > > 2.5.39-mm1 239.5 33% 3.4
> > >
> > > I think I'll set fifo_batch to 16 again...
> >
> > As not to compare oranges and apples, I'd very much like to see a
> > 2.5.39-mm1 vs 2.5.39-mm1 with fifo_batch=16. Con, would you do that?
> > Thanks!
>
> The presence of /proc/sys/vm/fifo_batch should make that pretty easy.

Thanks. That made it a lot easier and faster, and made me curious enough to
create a family or very interesting results. All these are with 2.5.39-mm1
with fifo_batch set to 1->16, average of three runs. The first result is the
unmodified 2.5.39-mm1 (fifo_batch=32).

io_load:
Kernel Time CPU% Ratio
2.5.39-mm1 239.5 32 3.54
2539mm1fb16 131.2 57 1.94
2539mm1fb8 109.1 68 1.61
2539mm1fb4 146.4 51 2.16
2539mm1fb2 112.7 65 1.67
2539mm1fb1 125.4 60 1.85

What's most interesting is the variation was small until the number was <8;
then the variation between runs increased. Dare I say it there appears to be
a sweet spot in the results.

Con
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