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cfq-iosched: sort RT queues into the rbtree

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Currently CFQ does a linked insert into the current list for RT
queues. We can just factor the class into the rb insertion,
and then we don't have to treat RT queues in a special way. It's
faster, too.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jens Axboe 2007-04-18 20:01:57 +02:00 committed by Jens Axboe
parent cc09e2990f
commit 0c534e0a46
1 changed files with 12 additions and 15 deletions
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27
block/cfq-iosched.c
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@ -471,7 +471,16 @@ static void cfq_service_tree_add(struct cfq_data *cfqd,
parent = *p;
__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
if (rb_key < __cfqq->rb_key)
/*
* sort RT queues first, we always want to give
* preference to them. after that, sort on the next
* service time.
*/
if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq))
p = &(*p)->rb_left;
else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq))
p = &(*p)->rb_right;
else if (rb_key < __cfqq->rb_key)
p = &(*p)->rb_left;
else {
p = &(*p)->rb_right;
@ -490,7 +499,6 @@ static void cfq_service_tree_add(struct cfq_data *cfqd,
static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted)
{
struct cfq_data *cfqd = cfqq->cfqd;
struct list_head *n;
/*
* Resorting requires the cfqq to be on the RR list already.
@ -500,25 +508,14 @@ static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted)
list_del_init(&cfqq->cfq_list);
if (cfq_class_rt(cfqq)) {
/*
* At to the front of the current list, but behind other
* RT queues.
*/
n = &cfqd->cur_rr;
while (n->next != &cfqd->cur_rr)
if (!cfq_class_rt(cfqq))
break;
list_add(&cfqq->cfq_list, n);
} else if (cfq_class_idle(cfqq)) {
if (cfq_class_idle(cfqq)) {
/*
* IDLE goes to the tail of the idle list
*/
list_add_tail(&cfqq->cfq_list, &cfqd->idle_rr);
} else {
/*
* So we get here, ergo the queue is a regular best-effort queue
* RT and BE queues, sort into the rbtree
*/
cfq_service_tree_add(cfqd, cfqq);
}