Messages in this thread | | | Date | Wed, 14 Nov 2007 19:55:26 +0100 | From | Ingo Molnar <> | Subject | Re: [patch] Give kjournald a IOPRIO_CLASS_RT io priority |
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* Arjan van de Ven <arjan@infradead.org> wrote:
> > > > * The read-a-different-kernel-tree task, average over 10 runs: > > > > o 2.6.24 - 46.8145945549 seconds > > > > o 2.6.24 + Arjan's patch - 39.6430601119 seconds > > > > > > > > * The large-linear-read task (on an 8GiB file), average over > > > > 10 runs: o 2.6.24 - 290.32522 seconds > > > > o 2.6.24 + Arjan's patch - 386.34860 seconds > > > > > > These are *large* differences, making this a very signifcant > > > patch. Much care is needed now. > > > > and the numbers suggest it's mostly a severe performance regression. > > That's not what i have expected - ho hum. Apologies for my earlier > > "please merge it already!" whining. > > that's.. not automatic; it depends on what the right thing is :-( What > for sure changes is that who gets to do IO changes. Some of the tests > we ran internally (we didn't publish yet because we saw REALLY large > variations for most of them even without any patch) show for example > that "dbench" got slower. But.. dbench gets slower when things get > more fair, and faster when things get unfair. What conclusion you draw > out of that is a whole different matter and depends on exactly what > the test is doing, and what is the right thing for the OS to do in > terms of who gets to do the IO.
yeah, i'd agree to not too much faith into dbench results.
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