On Mon, May 21 2007, Alan D. Brunelle wrote:
> Jens Axboe wrote:
> >On Tue, May 01 2007, Alan D. Brunelle wrote:
> >
> >>Jens Axboe wrote:
> >>
> >>>On Mon, Apr 30 2007, Alan D. Brunelle wrote:
> >>>
> >>>>The results from a single run of an AIM7 DBase load on a 16-way ia64
> >>>>box (64GB RAM + 144 FC disks) showed a slight regression (~0.5%) by
> >>>>adding in this patch. (Graph can be found at
> >>>>http://free.linux.hp.com/~adb/cfq/cfq_dbase.png ) It is only a single
> >>>>set of runs, on a single platform, but it is something to keep an eye
> >>>>on as the regression showed itself across the complete run.
> >>>>
> >>>Do you know if this regression is due to worse IO performance, or
> >>>increased system CPU usage?
> >>>
> >>We performed two point runs yesterday (20,000 and 50,000 tasks) and here
> >>are the results:
> >>
> >>Kernel Tasks Jobs per Minute %sys (avg)
> >>------ ----- --------------- ----------
> >>2.6.21 20000 60,831.1 39.83%
> >>CFQ br 20000 60,237.4 40.80%
> >> -0.98% +2.44%
> >>
> >>2.6.21 50000 60,881.6 40.43%
> >>CFQ br 50000 60,400.6 40.80%
> >> -0.79% +0.92%
> >>
> >>So we're seeing a slight IO performance regression with a slight
> >>increase in %system with the CFQ branch. (A chart of the complete run
> >>values is up on http://free.linux.hp.com/~adb/cfq/cfq_20k50k.png ).
> >>
> >
> >Alan, can you repeat that same run with this patch applied? It
> >reinstates the cfq lookup hash, which could account for increased system
> >utilization.
> >
>
> Hi Jens -
>
> This test was performed over the weekend, results are updated on
>
> http://free.linux.hp.com/~adb/cfq/cfq_dbase.png
Thanks a lot, Alan! So the cfq hash does indeed improve things a little,
that's a shame. I guess I'll just reinstate the hash lookup.
--
Jens Axboe
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