Messages in this thread | | | From | Jeff Moyer <> | Subject | Re: [RFC V2 PATCH 1/5] cfq-iosched: adapt slice to number of processes doing I/O | Date | Mon, 26 Oct 2009 11:10:17 -0400 |
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Corrado Zoccolo <czoccolo@gmail.com> writes:
> Hi Jeff, > On Wed, Oct 21, 2009 at 6:36 PM, Jeff Moyer <jmoyer@redhat.com> wrote: >> Corrado Zoccolo <czoccolo@gmail.com> writes: >> >> OK. The idea was to try to make the thing a bit more digestable. >> Honestly, I had to re-write it to figure out what it was doing. Could >> you rework it so the logic is more obvious to others and still correct? > > What about: > /* interested queues (we consider only the ones with the same priority class) */ > unsigned iq = cfq_get_avg_queues(cfqd, cfq_class_rt(cfqq)); > unsigned sync_slice = cfqd->cfq_slice[1]; > unsigned expected_latency = sync_slice * iq; > if (expected_latency > target_latency) { > unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; > /* scale low_slice according to IO priority and sync vs async */ > unsigned low_slice = min(slice, base_low_slice * slice / sync_slice); > /* the adapted slice value is scaled to fit all iqs into the target latency */ > slice = max(slice * cfq_target_latency / expected_latency, low_slice); > }
Yeah, that looks a ton better. Thanks for doing that!
Cheers, Jeff -- 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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