Message ID | 6b11c67ea495ed9d44f067622d852de4a510ce65.1634822969.git.asml.silence@gmail.com (mailing list archive) |
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State | New |
Headers | show
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Thu, 21 Oct 2021 06:30:57 -0700 (PDT) Received: from 127.0.0.1localhost ([185.69.145.206]) by smtp.gmail.com with ESMTPSA id q188sm1753987wma.1.2021.10.21.06.30.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Oct 2021 06:30:57 -0700 (PDT) From: Pavel Begunkov <asml.silence@gmail.com> To: linux-block@vger.kernel.org Cc: Jens Axboe <axboe@kernel.dk>, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christoph Lameter <cl@linux.com>, Tejun Heo <tj@kernel.org>, Dennis Zhou <dennis@kernel.org>, Pavel Begunkov <asml.silence@gmail.com> Subject: [PATCH v2 2/2] block: kill extra rcu lock/unlock in queue enter Date: Thu, 21 Oct 2021 14:30:52 +0100 Message-Id: <6b11c67ea495ed9d44f067622d852de4a510ce65.1634822969.git.asml.silence@gmail.com> X-Mailer: git-send-email 2.33.1 In-Reply-To: <cover.1634822969.git.asml.silence@gmail.com> References: <cover.1634822969.git.asml.silence@gmail.com> MIME-Version: 1.0 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: F3DC7F00023A X-Stat-Signature: grgy1r44rpgqp8n7umhczjypm6hdshrg Authentication-Results: imf11.hostedemail.com; 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Series |
optimise blk_try_enter_queue()
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expand
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diff --git a/block/blk-core.c b/block/blk-core.c index 88752e51d2b6..20e76aeb50f5 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -389,7 +389,7 @@ EXPORT_SYMBOL(blk_cleanup_queue); static bool blk_try_enter_queue(struct request_queue *q, bool pm) { rcu_read_lock(); - if (!percpu_ref_tryget_live(&q->q_usage_counter)) + if (!percpu_ref_tryget_live_rcu(&q->q_usage_counter)) goto fail; /*
blk_try_enter_queue() already takes rcu_read_lock/unlock, so we can avoid the second pair in percpu_ref_tryget_live(), use a newly added percpu_ref_tryget_live_rcu(). As rcu_read_lock/unlock imply barrier()s, it's pretty noticeable, especially for for !CONFIG_PREEMPT_RCU (default for some distributions), where __rcu_read_lock/unlock() are not inlined. 3.20% io_uring [kernel.vmlinux] [k] __rcu_read_unlock 3.05% io_uring [kernel.vmlinux] [k] __rcu_read_lock 2.52% io_uring [kernel.vmlinux] [k] __rcu_read_unlock 2.28% io_uring [kernel.vmlinux] [k] __rcu_read_lock Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> --- block/blk-core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)