Messages in this thread | | | Date | Fri, 9 Jul 2010 21:45:22 +0200 | Subject | Re: [PATCH 0/2] cfq-iosched: fixing RQ_NOIDLE handling. | From | Corrado Zoccolo <> |
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On Fri, Jul 9, 2010 at 4:07 PM, Jeff Moyer <jmoyer@redhat.com> wrote: > Corrado Zoccolo <czoccolo@gmail.com> writes: > >> On Wed, Jul 7, 2010 at 10:06 PM, Jeff Moyer <jmoyer@redhat.com> wrote: >>> Corrado Zoccolo <czoccolo@gmail.com> writes: >>> >>>> On Wed, Jul 7, 2010 at 7:03 PM, Jeff Moyer <jmoyer@redhat.com> wrote: >>>>> Corrado Zoccolo <czoccolo@gmail.com> writes: >>>>> >>>>>> Hi Jens, >>>>>> patch 8e55063 "cfq-iosched: fix corner cases in idling logic", is >>>>>> suspected for some regressions on high end hardware. >>>>>> The two patches from this series: >>>>>> - [PATCH 1/2] cfq-iosched: fix tree-wide handling of rq_noidle >>>>>> - [PATCH 2/2] cfq-iosched: RQ_NOIDLE enabled for SYNC_WORKLOAD >>>>>> fix two issues that I have identified, related to how RQ_NOIDLE is >>>>>> used by the upper layers. >>>>>> First patch makes sure that a RQ_NOIDLE coming after a sequence of >>>>>> possibly idling requests from the same queue on the no-idle tree will >>>>>> clear the noidle_tree_requires_idle flag. >>>>>> Second patch enables RQ_NOIDLE for queues in the idling tree, >>>>>> restoring the behaviour pre-8e55063 patch. >>>>> >>>>> Hi, Corrado, >>>>> >>>>> I ran your kernel through my tests. Here are the results, up against >>>>> vanilla, deadline, and the blk_yield patch set: >>>>> >>>> Hi Jeff, >>>> can you also add cfq with 8e55063 reverted to the testing mix? >>> >>> Sure, the results now look like this: >>> >>> just just >>> fs_mark fio mixed >>> -------------------------------+-------------- >>> deadline 529.44 151.4 | 450.0 78.2 >>> vanilla cfq 107.88 164.4 | 6.6 137.2 >>> blk_yield cfq 530.82 158.7 | 113.2 78.6 >>> corrado cfq 110.16 220.6 | 7.0 159.8 >>> 8e55063 revert 559.66 198.9 | 16.1 153.3 >>> >>> I had accidentally run your patch set (corrado cfq) on ext3, so the >>> numbers were a bit off (everything else was run against ext4). The >>> corrected numbers above reflect the performance on ext4, which is much >>> better for the sequential reader, but still not great for the fs_mark >>> run. Reverting 8e55063 definitely gets us into better shape. However, >>> if we care about the mixed workload, then it won't be enough. >> >> Wondering why deadline performs so well in the fs_mark workload. Is it >> because it doesn't distinguish between sync and async writes? > > It performs well because it doesn't do any idling. > >> Maybe we can achieve something similar by putting all sync writes >> (that are marked as REQ_NOIDLE) in the noidle tree? This, coupled with >> making jbd(2) perform sync writes, should make the yield automatic, >> since they all live in the same tree for which we don't idle between >> queues, and should be able to provide fairness compared to a >> sequential reader (that lives in the other tree). >> >> Can you test the attached patch, where I also added your changes to >> make jbd(2) to perform sync writes? > > I'm not sure what kernel you generated that patch against. I'm working > with 2.6.35-rc3 or later, and your patch does not apply there. It's Jens' block/for-2.6.36 tree.
> > Cheers, > Jeff >
-- __________________________________________________________________________
dott. Corrado Zoccolo mailto:czoccolo@gmail.com PhD - Department of Computer Science - University of Pisa, Italy -------------------------------------------------------------------------- The self-confidence of a warrior is not the self-confidence of the average man. The average man seeks certainty in the eyes of the onlooker and calls that self-confidence. The warrior seeks impeccability in his own eyes and calls that humbleness. Tales of Power - C. Castaneda -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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