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authorJens Axboe <jaxboe@fusionio.com>2011-08-19 08:34:48 +0200
committerJens Axboe <jaxboe@fusionio.com>2011-08-19 08:34:48 +0200
commitb53d1ed734a2b9af8da115b836b658daa7d47a48 (patch)
tree07ed12caa6fd50f97568f419448cf03906d980c4 /block
parent4853abaae7e4a2af938115ce9071ef8684fb7af4 (diff)
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Revert "cfq: Remove special treatment for metadata rqs."
We have a kernel build regression since 3.1-rc1, which is about 10% regression. The kernel source is in an ext3 filesystem. Alex Shi bisect it to commit: commit a07405b7802691d29ab3b23bdc76ee6d006aad0b Author: Justin TerAvest <teravest@google.com> Date: Sun Jul 10 22:09:19 2011 +0200 cfq: Remove special treatment for metadata rqs. Apparently this is caused by lack metadata preemption, where ext3/ext4 do use READ_META. I didn't see a way to fix the issue, so suggest reverting the patch. This reverts commit a07405b7802691d29ab3b23bdc76ee6d006aad0b. Reported-by: Alex Shi<alex.shi@intel.com> Reported-by: Shaohua Li<shaohua.li@intel.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'block')
-rw-r--r--block/cfq-iosched.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 65083453760..a33bd4377c6 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -130,6 +130,8 @@ struct cfq_queue {
unsigned long slice_end;
long slice_resid;
+ /* pending metadata requests */
+ int meta_pending;
/* number of requests that are on the dispatch list or inside driver */
int dispatched;
@@ -682,6 +684,9 @@ cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2,
if (rq_is_sync(rq1) != rq_is_sync(rq2))
return rq_is_sync(rq1) ? rq1 : rq2;
+ if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_META)
+ return rq1->cmd_flags & REQ_META ? rq1 : rq2;
+
s1 = blk_rq_pos(rq1);
s2 = blk_rq_pos(rq2);
@@ -1607,6 +1612,10 @@ static void cfq_remove_request(struct request *rq)
cfqq->cfqd->rq_queued--;
cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
rq_data_dir(rq), rq_is_sync(rq));
+ if (rq->cmd_flags & REQ_META) {
+ WARN_ON(!cfqq->meta_pending);
+ cfqq->meta_pending--;
+ }
}
static int cfq_merge(struct request_queue *q, struct request **req,
@@ -3360,6 +3369,13 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
return true;
/*
+ * 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->cmd_flags & REQ_META) && !cfqq->meta_pending)
+ return true;
+
+ /*
* Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
*/
if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
@@ -3423,6 +3439,8 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct cfq_io_context *cic = RQ_CIC(rq);
cfqd->rq_queued++;
+ if (rq->cmd_flags & REQ_META)
+ cfqq->meta_pending++;
cfq_update_io_thinktime(cfqd, cfqq, cic);
cfq_update_io_seektime(cfqd, cfqq, rq);