From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH 7/9] cfq-iosched: move cfq_group determination from cfq_find_alloc_queue() to cfq_get_queue() Date: Tue, 7 Jul 2015 11:35:59 -0400 Message-ID: <1436283361-3889-8-git-send-email-tj@kernel.org> References: <1436283361-3889-1-git-send-email-tj@kernel.org> Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=1nHfoXh8aIlbhQxz1I1ry5GXgxw80kWzyRwZElu6w1I=; b=LsAzKczj3OeJBBtqXqHuTQdSz4+L1nBjmzALovCDhdvGwAaP9IAuf/+eBXVtyjCX9T lUOR/A3MZCW61UApddxnrQZ1JCS/6Ngz79LKVFO5Fg7aBYiP1QYgpGYqy9IEZRSpu+N3 8Xsxy3rW5O70NPeQwwlmfTF9S/DxjInhmCkKxR00FE1b6jogZaipAjJi7PjaXk0Nzchx nFVfJSGi4TYERC3EpRSEfYmgEoCLgOX938TzGR2ZTy9vtf6ttwpKosFuuCAz617mQ6AC 05IK/271Jrlse/+5uCNfm4V4wQUTP77nkx/evgmyuHB5NHFbKxwWbz1sHYIcMdyG0I92 tS5w== In-Reply-To: <1436283361-3889-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: axboe@kernel.dk Cc: jack@suse.cz, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, kernel-team@fb.com, vgoyal@redhat.com, Tejun Heo , Arianna Avanzini This is necessary for making async cfq_cgroups per-cfq_group instead of per-cfq_data. While this change makes cfq_get_queue() perform RCU locking and look up cfq_group even when it reuses async queue, the extra overhead is extremely unlikely to be noticeable given that this is already sitting behind cic->cfqq[] cache and the overall cost of cfq operation. Signed-off-by: Tejun Heo Reviewed-by: Jeff Moyer Cc: Vivek Goyal Cc: Arianna Avanzini --- block/cfq-iosched.c | 28 ++++++++++++---------------- 1 file changed, 12 insertions(+), 16 deletions(-) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 146b03d..f3ea8a1 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3641,21 +3641,10 @@ static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { #endif /* CONFIG_CFQ_GROUP_IOSCHED */ static struct cfq_queue * -cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic, - struct bio *bio) +cfq_find_alloc_queue(struct cfq_data *cfqd, struct cfq_group *cfqg, bool is_sync, + struct cfq_io_cq *cic, struct bio *bio) { - struct blkcg *blkcg; struct cfq_queue *cfqq; - struct cfq_group *cfqg; - - rcu_read_lock(); - - blkcg = bio_blkcg(bio); - cfqg = cfq_lookup_create_cfqg(cfqd, blkcg); - if (!cfqg) { - cfqq = &cfqd->oom_cfqq; - goto out; - } cfqq = cic_to_cfqq(cic, is_sync); @@ -3675,8 +3664,6 @@ cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic, } else cfqq = &cfqd->oom_cfqq; } -out: - rcu_read_unlock(); return cfqq; } @@ -3706,6 +3693,14 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic, int ioprio = IOPRIO_PRIO_DATA(cic->ioprio); struct cfq_queue **async_cfqq; struct cfq_queue *cfqq; + struct cfq_group *cfqg; + + rcu_read_lock(); + cfqg = cfq_lookup_create_cfqg(cfqd, bio_blkcg(bio)); + if (!cfqg) { + cfqq = &cfqd->oom_cfqq; + goto out; + } if (!is_sync) { if (!ioprio_valid(cic->ioprio)) { @@ -3719,7 +3714,7 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic, goto out; } - cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio); + cfqq = cfq_find_alloc_queue(cfqd, cfqg, is_sync, cic, bio); /* * pin the queue now that it's allocated, scheduler exit will prune it @@ -3730,6 +3725,7 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic, } out: cfqq->ref++; + rcu_read_unlock(); return cfqq; } -- 2.4.3