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authorJens Axboe <jens.axboe@oracle.com>2009-04-15 12:12:46 +0200
committerJens Axboe <jens.axboe@oracle.com>2009-04-15 12:12:46 +0200
commit2d870722965211de072bb36b446a4df99dae07e1 (patch)
treee9b884d9969157f87e6a88a0de147af4022301e5 /block
parent40bb54d197a10fe86d73073ee8202ba2812a05fa (diff)
downloadlinux-2d870722965211de072bb36b446a4df99dae07e1.tar.bz2
cfq-iosched: tweak kick logic a bit more
We only kick the dispatch for an idling queue, if we think it's a (somewhat) fully merged request. Also allow a kick if we have other busy queues in the system, since we don't want to risk waiting for a potential merge in that case. It's better to get some work done and proceed. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block')
-rw-r--r--block/cfq-iosched.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index e59f2108272f..579f31822469 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1905,10 +1905,13 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
* of tiny requests, because we disrupt the normal plugging
* and merging. If the request is already larger than a single
* page, let it rip immediately. For that case we assume that
- * merging is already done.
+ * merging is already done. Ditto for a busy system that
+ * has other work pending, don't risk delaying until the
+ * idle timer unplug to continue working.
*/
if (cfq_cfqq_wait_request(cfqq)) {
- if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE) {
+ if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
+ cfqd->busy_queues > 1) {
del_timer(&cfqd->idle_slice_timer);
blk_start_queueing(cfqd->queue);
}