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[PATCH] cfq-iosched: use metadata read flag

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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>
This commit is contained in:
Jens Axboe 2006-07-23 01:42:19 +02:00 committed by Jens Axboe
parent caa38fb0f4
commit 374f84ac39
1 changed files with 24 additions and 0 deletions
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24
block/cfq-iosched.c
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@ -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)) {
*/