Messages in this thread | | | Date | Mon, 21 May 2007 14:19:44 +0200 | From | Jens Axboe <> | Subject | Re: CFQ IO scheduler patch series - AIM7 DBase results on a 16-way IA64 |
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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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