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authorJens Axboe <axboe@fb.com>2015-04-17 16:15:18 -0600
committerJens Axboe <axboe@fb.com>2015-05-05 13:32:47 -0600
commitc4cf5261f8bffd9de132b50660a69148e7575bd6 (patch)
treec3ff2d0d2db5f7392e8651b4f0d2958895faf8b2 /drivers/md/dm-snap.c
parentd9cee5d4f66ef36f69b0108dedbad7f7009bb6a8 (diff)
bio: skip atomic inc/dec of ->bi_remaining for non-chains
Struct bio has an atomic ref count for chained bio's, and we use this to know when to end IO on the bio. However, most bio's are not chained, so we don't need to always introduce this atomic operation as part of ending IO. Add a helper to elevate the bi_remaining count, and flag the bio as now actually needing the decrement at end_io time. Rename the field to __bi_remaining to catch any current users of this doing the incrementing manually. For high IOPS workloads, this reduces the overhead of bio_endio() substantially. Tested-by: Robert Elliott <elliott@hp.com> Acked-by: Kent Overstreet <kent.overstreet@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'drivers/md/dm-snap.c')
-rw-r--r--drivers/md/dm-snap.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index f83a0f3fc365..8bfeae218531 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1478,7 +1478,7 @@ out:
if (full_bio) {
full_bio->bi_end_io = pe->full_bio_end_io;
full_bio->bi_private = pe->full_bio_private;
- atomic_inc(&full_bio->bi_remaining);
+ bio_inc_remaining(full_bio);
}
increment_pending_exceptions_done_count();