Messages in this thread | | | Date | Mon, 21 May 2007 11:11:10 -0400 | From | "Alan D. Brunelle" <> | Subject | Re: CFQ IO scheduler patch series - AIM7 DBase results on a 16-way IA64 |
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Jens Axboe wrote: > 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. > > You're welcome Jens, but remember: It's one set of data; from one benchmark; on one architecture; on one platform...don't know if you should scrap the whole thing for that! :-) At the very least, I could look into trying it out on another architecture. Let me see what I can dig up...
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