From bf57225670bcbeb357182d800736b4782cde7295 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@suse.de>
Date: Wed, 19 Jul 2006 20:29:12 +0200
Subject: [PATCH] [PATCH] cfq-iosched: improve queue preemption
Don't touch the current queues, just make sure that the wanted queue
is selected next. Simplifies the logic.
Signed-off-by: Jens Axboe <axboe@suse.de>
---
block/cfq-iosched.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 9f684cc66bd163..1411048359524f 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1539,17 +1539,19 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
*/
static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
- struct cfq_queue *__cfqq, *next;
-
- list_for_each_entry_safe(__cfqq, next, &cfqd->cur_rr, cfq_list)
- cfq_resort_rr_list(__cfqq, 1);
+ cfq_slice_expired(cfqd, 1);
if (!cfqq->slice_left)
cfqq->slice_left = cfq_prio_to_slice(cfqd, cfqq) / 2;
+ /*
+ * Put the new queue at the front of the of the current list,
+ * so we know that it will be selected next.
+ */
+ BUG_ON(!cfq_cfqq_on_rr(cfqq));
+ list_move(&cfqq->cfq_list, &cfqd->cur_rr);
+
cfqq->slice_end = cfqq->slice_left + jiffies;
- cfq_slice_expired(cfqd, 1);
- __cfq_set_active_queue(cfqd, cfqq);
}
/*
--
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