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authorJens Axboe <jens.axboe@oracle.com>2007-01-02 18:32:11 +0100
committerLinus Torvalds <torvalds@woody.osdl.org>2007-01-02 09:46:16 -0800
commitec8acb6904fabb8e741f741ec99bb1c18f2b3dee (patch)
tree9d4da59b2ccc4b1424b90497c7b26778c272ca5a
parentdc3c3377f03634d351fafdfe35b237b283586c04 (diff)
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[PATCH] cfq-iosched: merging problem
Two issues: - The final return 1 should be a return 0, otherwise comparing cfqq is a noop. - bio_sync() only checks the sync flag, while rq_is_sync() checks both for READ and sync. The latter is what we want. Expand the bio check to include reads, and relax the restriction to allow merging of async io into sync requests. In the future we want to clean up the SYNC logic, right now it means both sync request (such as READ and O_DIRECT WRITE) and unplug-on-issue. Leave that for later. Signed-off-by: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--block/cfq-iosched.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 4b4217d9be7..07b70624377 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -577,9 +577,9 @@ static int cfq_allow_merge(request_queue_t *q, struct request *rq,
pid_t key;
/*
- * Disallow merge, if bio and rq aren't both sync or async
+ * Disallow merge of a sync bio into an async request.
*/
- if (!!bio_sync(bio) != !!rq_is_sync(rq))
+ if ((bio_data_dir(bio) == READ || bio_sync(bio)) && !rq_is_sync(rq))
return 0;
/*
@@ -592,7 +592,7 @@ static int cfq_allow_merge(request_queue_t *q, struct request *rq,
if (cfqq == RQ_CFQQ(rq))
return 1;
- return 1;
+ return 0;
}
static inline void