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authorJens Axboe <jaxboe@fusionio.com>2011-04-19 13:32:46 +0200
committerJens Axboe <jaxboe@fusionio.com>2011-04-19 13:32:46 +0200
commitc21e6beba8835d09bb80e34961430b13e60381c5 (patch)
treecdf6f6d40130b95e641ab5db1de0f6ecc179054a /drivers/scsi/scsi_lib.c
parent5f45c69589b7d2953584e6cd0b31e35dbe960ad0 (diff)
block: get rid of QUEUE_FLAG_REENTER
We are currently using this flag to check whether it's safe to call into ->request_fn(). If it is set, we punt to kblockd. But we get a lot of false positives and excessive punts to kblockd, which hurts performance. The only real abuser of this infrastructure is SCSI. So export the async queue run and convert SCSI over to use that. There's room for improvement in that SCSI need not always use the async call, but this fixes our performance issue and they can fix that up in due time. Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'drivers/scsi/scsi_lib.c')
-rw-r--r--drivers/scsi/scsi_lib.c17
1 files changed, 1 insertions, 16 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index ab55c2fa7ce2..e9901b8f8443 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -411,8 +411,6 @@ static void scsi_run_queue(struct request_queue *q)
list_splice_init(&shost->starved_list, &starved_list);
while (!list_empty(&starved_list)) {
- int flagset;
-
/*
* As long as shost is accepting commands and we have
* starved queues, call blk_run_queue. scsi_request_fn
@@ -435,20 +433,7 @@ static void scsi_run_queue(struct request_queue *q)
continue;
}
- spin_unlock(shost->host_lock);
-
- spin_lock(sdev->request_queue->queue_lock);
- flagset = test_bit(QUEUE_FLAG_REENTER, &q->queue_flags) &&
- !test_bit(QUEUE_FLAG_REENTER,
- &sdev->request_queue->queue_flags);
- if (flagset)
- queue_flag_set(QUEUE_FLAG_REENTER, sdev->request_queue);
- __blk_run_queue(sdev->request_queue);
- if (flagset)
- queue_flag_clear(QUEUE_FLAG_REENTER, sdev->request_queue);
- spin_unlock(sdev->request_queue->queue_lock);
-
- spin_lock(shost->host_lock);
+ blk_run_queue_async(sdev->request_queue);
}
/* put any unprocessed entries back */
list_splice(&starved_list, &shost->starved_list);