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. 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
