Messages in this thread | | | Date | Sat, 3 Oct 2009 15:50:46 +0200 | From | Jens Axboe <> | Subject | Re: [PATCH] cfq: enable idle for seeky processes on rotational NCQ devices |
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On Sat, Oct 03 2009, Corrado Zoccolo wrote: > Idle window is currently disabled for seeky processes on all NCQ devices. > This is causing large latencies when seeky processes are competing with async writes, > for rotational NCQ devices. > > This patch, based on Vivek Goyal's original idea (http://lkml.org/lkml/2009/7/12/110), > enables idle window for seeky processes on rotational NCQ devices. > As for non-NCQ devices, a smaller idle window (2ms) is used > for seeky processes compared to normal I/O (8ms). > > RAIDs should be marked as non-rotational as well (and probably a better flag > name should be devised), since they can carry multiple operations in parallel. > > Signed-off-by: Corrado Zoccolo <czoccolo@gmail.com> > --- > diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c > index 1ca813b..7116f11 100644 > --- a/block/cfq-iosched.c > +++ b/block/cfq-iosched.c > @@ -1951,10 +1951,12 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, > enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); > > if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || > - (cfqd->hw_tag && CIC_SEEKY(cic))) > + (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag && CIC_SEEKY(cic))) > enable_idle = 0; > else if (sample_valid(cic->ttime_samples)) { > - if (cic->ttime_mean > cfqd->cfq_slice_idle) > + unsigned idle_time = CIC_SEEKY(cic) ? CFQ_MIN_TT > + : cfqd->cfq_slice_idle; > + if (cic->ttime_mean > idle_time) > enable_idle = 0; > else > enable_idle = 1;
Please don't use the ?: constructs, they are not very readable (especially not with multi-lines).
Can you resend this on top of the current for-linus branch, it has a few cfq patches that cause this not to apply anyway.
-- Jens Axboe
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