On Fri, Oct 02, 2009 at 05:32:00PM +0200, Mike Galbraith wrote: > On Fri, 2009-10-02 at 17:27 +0200, Corrado Zoccolo wrote: > > On Fri, Oct 2, 2009 at 2:49 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: > > > On Fri, Oct 02, 2009 at 12:55:25PM +0200, Corrado Zoccolo wrote: > > > > > > Actually I am not touching this code. Looking at the V10, I have not > > > changed anything here in idling code. > > > > I based my analisys on the original patch: > > http://lkml.indiana.edu/hypermail/linux/kernel/0907.1/01793.html > > > > Mike, can you confirm which version of the fairness patch did you use > > in your tests? > > That would be this one-liner. > Ok. Thanks. Sorry, I got confused and thought that you are using "io controller patches" with fairness=1. In that case, Corrado's suggestion of refining it further and disabling idling for seeky process only on non-rotational media (SSD and hardware RAID), makes sense to me. Thanks Vivek > o CFQ provides fair access to disk in terms of disk time used to processes. > Fairness is provided for the applications which have their think time with > in slice_idle (8ms default) limit. > > o CFQ currently disables idling for seeky processes. So even if a process > has think time with-in slice_idle limits, it will still not get fair share > of disk. Disabling idling for a seeky process seems good from throughput > perspective but not necessarily from fairness perspecitve. > > 0 Do not disable idling based on seek pattern of process if a user has set > /sys/block/<disk>/queue/iosched/fairness = 1. > > Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx> > --- > block/cfq-iosched.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > Index: linux-2.6/block/cfq-iosched.c > =================================================================== > --- linux-2.6.orig/block/cfq-iosched.c > +++ linux-2.6/block/cfq-iosched.c > @@ -1953,7 +1953,7 @@ cfq_update_idle_window(struct cfq_data * > 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))) > + (!cfqd->cfq_fairness && cfqd->hw_tag && CIC_SEEKY(cic))) > enable_idle = 0; > else if (sample_valid(cic->ttime_samples)) { > if (cic->ttime_mean > cfqd->cfq_slice_idle) > -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
