From: Mike Snitzer Subject: [PATCH v2 1/2] block: skip elevator initialization for flush requests Date: Tue, 1 Feb 2011 17:46:12 -0500 Message-ID: <1296600373-6906-1-git-send-email-snitzer@redhat.com> References: <20110201185225.GT14211@htj.dyndns.org> Cc: tytso@mit.edu, djwong@us.ibm.com, shli@kernel.org, neilb@suse.de, adilger.kernel@dilger.ca, jack@suse.cz, linux-kernel@vger.kernel.org, kmannth@us.ibm.com, cmm@us.ibm.com, linux-ext4@vger.kernel.org, rwheeler@redhat.com, hch@lst.de, josef@redhat.com, jmoyer@redhat.com, vgoyal@redhat.com, snitzer@redhat.com To: Tejun Heo , Jens Axboe Return-path: In-Reply-To: <20110201185225.GT14211@htj.dyndns.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Skip elevator initialization during request allocation if REQ_SORTED is not set in the @rw_flags passed to the request allocator. Set REQ_SORTED for all requests that may be put on IO scheduler. Flush requests are not put on IO scheduler so REQ_SORTED is not set for them. Signed-off-by: Mike Snitzer --- block/blk-core.c | 24 +++++++++++++++++++----- 1 files changed, 19 insertions(+), 5 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 72dd23b..f6fcc64 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -764,7 +764,7 @@ static struct request *get_request(struct request_queue *q, int rw_flags, struct request_list *rl = &q->rq; struct io_context *ioc = NULL; const bool is_sync = rw_is_sync(rw_flags) != 0; - int may_queue, priv; + int may_queue, priv = 0; may_queue = elv_may_queue(q, rw_flags); if (may_queue == ELV_MQUEUE_NO) @@ -808,9 +808,14 @@ static struct request *get_request(struct request_queue *q, int rw_flags, rl->count[is_sync]++; rl->starved[is_sync] = 0; - priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); - if (priv) - rl->elvpriv++; + /* + * Only initialize elevator data if REQ_SORTED is set. + */ + if (rw_flags & REQ_SORTED) { + priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); + if (priv) + rl->elvpriv++; + } if (blk_queue_io_stat(q)) rw_flags |= REQ_IO_STAT; @@ -1197,6 +1202,7 @@ static int __make_request(struct request_queue *q, struct bio *bio) const unsigned short prio = bio_prio(bio); const bool sync = !!(bio->bi_rw & REQ_SYNC); const bool unplug = !!(bio->bi_rw & REQ_UNPLUG); + const bool flush = !!(bio->bi_rw & (REQ_FLUSH | REQ_FUA)); const unsigned long ff = bio->bi_rw & REQ_FAILFAST_MASK; int where = ELEVATOR_INSERT_SORT; int rw_flags; @@ -1210,7 +1216,7 @@ static int __make_request(struct request_queue *q, struct bio *bio) spin_lock_irq(q->queue_lock); - if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) { + if (flush) { where = ELEVATOR_INSERT_FLUSH; goto get_rq; } @@ -1293,6 +1299,14 @@ get_rq: rw_flags |= REQ_SYNC; /* + * Set REQ_SORTED for all requests that may be put on IO scheduler. + * The request allocator's IO scheduler initialization will be skipped + * if REQ_SORTED is not set. + */ + if (!flush) + rw_flags |= REQ_SORTED; + + /* * Grab a free request. This is might sleep but can not fail. * Returns with the queue unlocked. */ -- 1.7.3.4