diff options
| author | Jens Axboe <jens.axboe@oracle.com> | 2006-12-22 09:38:53 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.osdl.org> | 2006-12-22 14:13:08 -0800 |
| commit | 719d34027e1a186e46a3952e8a24bf91ecc33837 (patch) | |
| tree | f0b9074069777c430045e7be803d8c5a2187ecc9 | |
| parent | c2fda5fed81eea077363b285b66eafce20dfd45a (diff) | |
[PATCH] cfq-iosched: tighten allow merge criteria
The logic in cfq_allow_merge() wasn't clear enough - basically allow
merging for the same queues only. Do a fast check for 'rq and bio both
sync/async' before doing the cfqq hash lookup.
This is verified to work with the fixed elv_try_merge() from commit
bb4067e34159648d394943d5e2a011f838bff22f.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | block/cfq-iosched.c | 21 |
1 files changed, 8 insertions, 13 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 9fc5eafa6c0e..4b4217d9be78 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -577,25 +577,20 @@ static int cfq_allow_merge(request_queue_t *q, struct request *rq, pid_t key; /* - * If bio is async or a write, always allow merge + * Disallow merge, if bio and rq aren't both sync or async */ - if (!bio_sync(bio) || rw == WRITE) - return 1; - - /* - * bio is sync. if request is not, disallow. - */ - if (!rq_is_sync(rq)) + if (!!bio_sync(bio) != !!rq_is_sync(rq)) return 0; /* - * Ok, both bio and request are sync. Allow merge if they are - * from the same queue. + * Lookup the cfqq that this bio will be queued with. Allow + * merge only if rq is queued there. */ - key = cfq_queue_pid(current, rw, 1); + key = cfq_queue_pid(current, rw, bio_sync(bio)); cfqq = cfq_find_cfq_hash(cfqd, key, current->ioprio); - if (cfqq != RQ_CFQQ(rq)) - return 0; + + if (cfqq == RQ_CFQQ(rq)) + return 1; return 1; } |