From: Namhyung Kim <namhyung@gmail.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH 2/4] cfq-iosched: reduce bit operations in cfq_choose_req()
Date: Tue, 24 May 2011 12:18:49 +0900 [thread overview]
Message-ID: <1306207131-2296-2-git-send-email-namhyung@gmail.com> (raw)
In-Reply-To: <1306207131-2296-1-git-send-email-namhyung@gmail.com>
Reduce the number of bit operations in cfq_choose_req() on average
(and worst) cases.
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
---
block/cfq-iosched.c | 14 +++++---------
1 files changed, 5 insertions(+), 9 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 151a050e692c..a79e62063144 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -665,15 +665,11 @@ cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2,
if (rq2 == NULL)
return rq1;
- if (rq_is_sync(rq1) && !rq_is_sync(rq2))
- return rq1;
- else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
- return rq2;
- if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
- return rq1;
- else if ((rq2->cmd_flags & REQ_META) &&
- !(rq1->cmd_flags & REQ_META))
- return rq2;
+ if (rq_is_sync(rq1) != rq_is_sync(rq2))
+ return rq_is_sync(rq1) ? rq1 : rq2;
+
+ if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_META)
+ return rq1->cmd_flags & REQ_META ? rq1 : rq2;
s1 = blk_rq_pos(rq1);
s2 = blk_rq_pos(rq2);
--
1.7.5.2
next prev parent reply other threads:[~2011-05-24 3:19 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-24 3:18 [PATCH 1/4] cfq-iosched: algebraic simplification in cfq_prio_to_maxrq() Namhyung Kim
2011-05-24 3:18 ` Namhyung Kim [this message]
2011-05-24 17:34 ` [PATCH 2/4] cfq-iosched: reduce bit operations in cfq_choose_req() Justin TerAvest
2011-05-25 2:34 ` Namhyung Kim
2011-05-24 3:18 ` [PATCH 3/4] cfq-iosched: remove unused 'group_changed' in cfq_service_tree_add() Namhyung Kim
2011-05-24 17:32 ` Justin TerAvest
2011-05-24 3:18 ` [PATCH 4/4] cfq-iosched: free cic_index if cfqd allocation fails Namhyung Kim
2011-05-24 8:13 ` [PATCH 1/4] cfq-iosched: algebraic simplification in cfq_prio_to_maxrq() Jens Axboe
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