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authorDivyesh Shah <dpshah@google.com>2010-04-08 21:14:23 -0700
committerJens Axboe <jens.axboe@oracle.com>2010-04-09 08:36:07 +0200
commit812d402648f4fc1ab1091b2172a46fc1b367c724 (patch)
tree9dc52d5bfdbc170559169a0157ed3295d551e9cf /block/cfq-iosched.c
parent84c124da9ff50bd71fab9c939ee5b7cd8bef2bd9 (diff)
downloadtalos-op-linux-812d402648f4fc1ab1091b2172a46fc1b367c724.tar.gz
talos-op-linux-812d402648f4fc1ab1091b2172a46fc1b367c724.zip
blkio: Add io_merged stat
This includes both the number of bios merged into requests belonging to this cgroup as well as the number of requests merged together. In the past, we've observed different merging behavior across upstream kernels, some by design some actual bugs. This stat helps a lot in debugging such problems when applications report decreased throughput with a new kernel version. This needed adding an extra elevator function to capture bios being merged as I did not want to pollute elevator code with blkiocg knowledge and hence needed the accounting invocation to come from CFQ. Signed-off-by: Divyesh Shah<dpshah@google.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/cfq-iosched.c')
-rw-r--r--block/cfq-iosched.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 5617ae030b15..4eb1906cf6c6 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1467,6 +1467,14 @@ static void cfq_merged_request(struct request_queue *q, struct request *req,
}
}
+static void cfq_bio_merged(struct request_queue *q, struct request *req,
+ struct bio *bio)
+{
+ struct cfq_queue *cfqq = RQ_CFQQ(req);
+ blkiocg_update_io_merged_stats(&cfqq->cfqg->blkg, bio_data_dir(bio),
+ cfq_bio_sync(bio));
+}
+
static void
cfq_merged_requests(struct request_queue *q, struct request *rq,
struct request *next)
@@ -1484,6 +1492,8 @@ cfq_merged_requests(struct request_queue *q, struct request *rq,
if (cfqq->next_rq == next)
cfqq->next_rq = rq;
cfq_remove_request(next);
+ blkiocg_update_io_merged_stats(&cfqq->cfqg->blkg, rq_data_dir(next),
+ rq_is_sync(next));
}
static int cfq_allow_merge(struct request_queue *q, struct request *rq,
@@ -3861,6 +3871,7 @@ static struct elevator_type iosched_cfq = {
.elevator_merged_fn = cfq_merged_request,
.elevator_merge_req_fn = cfq_merged_requests,
.elevator_allow_merge_fn = cfq_allow_merge,
+ .elevator_bio_merged_fn = cfq_bio_merged,
.elevator_dispatch_fn = cfq_dispatch_requests,
.elevator_add_req_fn = cfq_insert_request,
.elevator_activate_req_fn = cfq_activate_request,
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