From 0c534e0a463e2eeafc97ba25ab23c14f3cdf2bdb Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 18 Apr 2007 20:01:57 +0200 Subject: [PATCH] cfq-iosched: sort RT queues into the rbtree 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 --- block/cfq-iosched.c | 27 ++++++++++++--------------- 1 file changed, 12 insertions(+), 15 deletions(-) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 55c476baa692..81c057eadfcc 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -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); } -- 2.20.1