From: Divyesh Shah Date: Thu, 7 Jan 2010 02:58:20 +0000 (-0800) Subject: cfq-iosched: Respect ioprio_class when preempting X-Git-Tag: v2.6.33-rc5~8^2~3 X-Git-Url: http://ftp.safe.ca/?p=safe%2Fjmp%2Flinux-2.6;a=commitdiff_plain;h=875feb63b9567442be73efbcc9a8470e376d6423 cfq-iosched: Respect ioprio_class when preempting In cfq_should_preempt(), we currently allow some cases where a non-RT request can preempt an ongoing RT cfqq timeslice. This should not happen. Examples include: o A sync_noidle wl type non-RT request pre-empting a sync_noidle wl type cfqq on which we are idling. o Once we have per-cgroup async queues, a non-RT sync request pre-empting a RT async cfqq. Signed-off-by: Divyesh Shah Signed-off-by: Jens Axboe --- diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 918c7fd..ee130f1 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3077,6 +3077,12 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, return true; /* + * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice. + */ + if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq)) + return false; + + /* * if the new request is sync, but the currently running queue is * not, let the sync request have priority. */