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authorJens Axboe <axboe@suse.de>2006-07-23 01:42:19 +0200
committerJens Axboe <axboe@nelson.home.kernel.dk>2006-09-30 20:29:43 +0200
commit374f84ac39ec7829a57a66efd5125d3561ff0e00 (patch)
treea1303aba1804f621ebea8304ba94e02c16a70a5c
parentcaa38fb0f481a3cb732b115cb59bfa6b59b6daaf (diff)
[PATCH] cfq-iosched: use metadata read flag
Give meta data reads preference over regular reads, as the process often needs to get that out of the way to do the io it was actually interested in. Signed-off-by: Jens Axboe <axboe@suse.de>
-rw-r--r--block/cfq-iosched.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 14110483595..6dbee46240c 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -141,6 +141,8 @@ struct cfq_queue {
int queued[2];
/* currently allocated requests */
int allocated[2];
+ /* pending metadata requests */
+ int meta_pending;
/* fifo list of requests in sort_list */
struct list_head fifo;
@@ -248,6 +250,10 @@ cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2)
return rq1;
else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
return rq2;
+ if (rq_is_meta(rq1) && !rq_is_meta(rq2))
+ return rq1;
+ else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
+ return rq2;
s1 = rq1->sector;
s2 = rq2->sector;
@@ -510,6 +516,11 @@ static void cfq_remove_request(struct request *rq)
list_del_init(&rq->queuelist);
cfq_del_rq_rb(rq);
+
+ if (rq_is_meta(rq)) {
+ WARN_ON(!cfqq->meta_pending);
+ cfqq->meta_pending--;
+ }
}
static int
@@ -1527,8 +1538,18 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
*/
if (new_cfqq->slice_left < cfqd->cfq_slice_idle)
return 0;
+ /*
+ * if the new request is sync, but the currently running queue is
+ * not, let the sync request have priority.
+ */
if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
return 1;
+ /*
+ * So both queues are sync. Let the new request get disk time if
+ * it's a metadata request and the current queue is doing regular IO.
+ */
+ if (rq_is_meta(rq) && !cfqq->meta_pending)
+ return 1;
return 0;
}
@@ -1564,6 +1585,9 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
{
struct cfq_io_context *cic = RQ_CIC(rq);
+ if (rq_is_meta(rq))
+ cfqq->meta_pending++;
+
/*
* check if this request is a better next-serve candidate)) {
*/