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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/elevator.c
parent84c124da9ff50bd71fab9c939ee5b7cd8bef2bd9 (diff)
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/elevator.c')
-rw-r--r--block/elevator.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/block/elevator.c b/block/elevator.c
index 76e3702d538..5e734592bb4 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -539,6 +539,15 @@ void elv_merge_requests(struct request_queue *q, struct request *rq,
q->last_merge = rq;
}
+void elv_bio_merged(struct request_queue *q, struct request *rq,
+ struct bio *bio)
+{
+ struct elevator_queue *e = q->elevator;
+
+ if (e->ops->elevator_bio_merged_fn)
+ e->ops->elevator_bio_merged_fn(q, rq, bio);
+}
+
void elv_requeue_request(struct request_queue *q, struct request *rq)
{
/*