diff options
author | Shaohua Li <shaohua.li@intel.com> | 2011-12-16 08:00:31 -0500 |
---|---|---|
committer | Jens Axboe <axboe@kernel.dk> | 2011-12-16 08:00:31 -0500 |
commit | 274193224cdabd687d804a26e0150bb20f2dd52c (patch) | |
tree | f07a788183f2ac91b9b16295f8f146bd5b88fb96 /block | |
parent | 4a0b75c7d02c2bd46ed227d4ba5941ba8a0aba5d (diff) |
block: recursive merge requests
In my workload, thread 1 accesses a, a+2, ..., thread 2 accesses a+1,
a+3,.... When the requests are flushed to queue, a and a+1 are merged
to (a, a+1), a+2 and a+3 too to (a+2, a+3), but (a, a+1) and (a+2, a+3)
aren't merged.
With recursive merge below, the workload throughput gets improved 20%
and context switch drops 60%.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r-- | block/elevator.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/block/elevator.c b/block/elevator.c index 91e18f8af9be..99838f460b44 100644 --- a/block/elevator.c +++ b/block/elevator.c | |||
@@ -515,6 +515,7 @@ static bool elv_attempt_insert_merge(struct request_queue *q, | |||
515 | struct request *rq) | 515 | struct request *rq) |
516 | { | 516 | { |
517 | struct request *__rq; | 517 | struct request *__rq; |
518 | bool ret; | ||
518 | 519 | ||
519 | if (blk_queue_nomerges(q)) | 520 | if (blk_queue_nomerges(q)) |
520 | return false; | 521 | return false; |
@@ -528,14 +529,21 @@ static bool elv_attempt_insert_merge(struct request_queue *q, | |||
528 | if (blk_queue_noxmerges(q)) | 529 | if (blk_queue_noxmerges(q)) |
529 | return false; | 530 | return false; |
530 | 531 | ||
532 | ret = false; | ||
531 | /* | 533 | /* |
532 | * See if our hash lookup can find a potential backmerge. | 534 | * See if our hash lookup can find a potential backmerge. |
533 | */ | 535 | */ |
534 | __rq = elv_rqhash_find(q, blk_rq_pos(rq)); | 536 | while (1) { |
535 | if (__rq && blk_attempt_req_merge(q, __rq, rq)) | 537 | __rq = elv_rqhash_find(q, blk_rq_pos(rq)); |
536 | return true; | 538 | if (!__rq || !blk_attempt_req_merge(q, __rq, rq)) |
539 | break; | ||
537 | 540 | ||
538 | return false; | 541 | /* The merged request could be merged with others, try again */ |
542 | ret = true; | ||
543 | rq = __rq; | ||
544 | } | ||
545 | |||
546 | return ret; | ||
539 | } | 547 | } |
540 | 548 | ||
541 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) | 549 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |