From nobody Fri Oct 3 03:20:13 2025 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BF71C2EB5BF; Mon, 8 Sep 2025 09:29:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757323771; cv=none; b=IfseIv4Je2DWNc0qfqGZpB9UYeLFpcranyhgdbYIvX9YgWFvROSSk4dLpYwMYc0gsVFOSk3jYMT8VgztVQAh+Hy98/ePxoAj+TNtOHZ3agakWcd4JoihWVcH9aha9lOft8sy0KVtG0p4wuLQLndiifCwoAiimoM3KXGW10SG/0Y= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757323771; c=relaxed/simple; bh=zcUoMdH7hBNz7MSsR7/dhT0RSHn4wSbUyGgnmqAeiNs=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=f7ZbRV6nEpZ/8ZKI4X6r2cbt2bi2sbFjuNyul212MmR8qalVlnYrJCHEmDJAyHj62qgH6hVB4CzlNMdCsQ8/izjw5tfLfMj3XMFM0B5YFhQ4xdChwEnb1WR8TCpxU8W3efgaHlq5lhxrwMvlPTG0i7pe+le3igAu6lSEXuGcxhc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.93.142]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4cL1qp4pNVzKHN7F; Mon, 8 Sep 2025 17:29:26 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id BE88F1A0E98; Mon, 8 Sep 2025 17:29:26 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP4 (Coremail) with SMTP id gCh0CgAXYIzzob5oGjMyBw--.46699S5; Mon, 08 Sep 2025 17:29:26 +0800 (CST) From: Yu Kuai To: dlemoal@kernel.org, hare@suse.de, bvanassche@acm.org, ming.lei@redhat.com, tj@kernel.org, josef@toxicpanda.com, axboe@kernel.dk, yukuai3@huawei.com Cc: cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com Subject: [PATCH v4 for-6.18/block 1/5] blk-mq-sched: introduce high level elevator lock Date: Mon, 8 Sep 2025 17:20:03 +0800 Message-Id: <20250908092007.3796967-2-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20250908092007.3796967-1-yukuai1@huaweicloud.com> References: <20250908092007.3796967-1-yukuai1@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: gCh0CgAXYIzzob5oGjMyBw--.46699S5 X-Coremail-Antispam: 1UD129KBjvJXoWxXw1UJw47Gr1fGr1kCr1kGrg_yoWrGF45pF 4rGa98Kw1kXF42gF97A3W3Xw43K34v9r9xZrWxZ3y7tFn7Jr4fW3W8GF1UZF4UZr4fGFsF qr18taykWay7G3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUmY14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_Jr4l82xGYIkIc2 x26xkF7I0E14v26r4j6ryUM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJw A2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq3wAS 0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2 IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0 Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2kIc2 xKxwCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWU JVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67 kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY 6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0x vEx4A2jsIE14v26r4j6F4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr1j6F4UJbIYCTnIWIev Ja73UjIFyTuYvjfU8XdbUUUUU X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ Content-Type: text/plain; charset="utf-8" From: Yu Kuai Currently, both mq-deadline and bfq have global spin lock that will be grabbed inside elevator methods like dispatch_request, insert_requests, and bio_merge. And the global lock is the main reason mq-deadline and bfq can't scale very well. While dispatching request, blk_mq_get_disatpch_budget() and blk_mq_get_driver_tag() must be called, and they are not ready to be called inside elevator methods, hence introduce a new method like dispatch_requests is not possible. Hence introduce a new high level elevator lock, currently it is protecting dispatch_request only. Following patches will convert mq-deadline and bfq to use this lock and finally support request batch dispatching by calling the method multiple time while holding the lock. Signed-off-by: Yu Kuai --- block/blk-mq-sched.c | 9 ++++++++- block/elevator.c | 1 + block/elevator.h | 31 +++++++++++++++++++++++++++++-- 3 files changed, 38 insertions(+), 3 deletions(-) diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c index d06bb137a743..6f2b0573a8ff 100644 --- a/block/blk-mq-sched.c +++ b/block/blk-mq-sched.c @@ -113,7 +113,14 @@ static int __blk_mq_do_dispatch_sched(struct blk_mq_hw= _ctx *hctx) if (budget_token < 0) break; =20 - rq =3D e->type->ops.dispatch_request(hctx); + if (blk_queue_sq_sched(q)) { + elevator_dispatch_lock(e); + rq =3D e->type->ops.dispatch_request(hctx); + elevator_dispatch_unlock(e); + } else { + rq =3D e->type->ops.dispatch_request(hctx); + } + if (!rq) { blk_mq_put_dispatch_budget(q, budget_token); /* diff --git a/block/elevator.c b/block/elevator.c index e2ebfbf107b3..e132a24f9ce3 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -146,6 +146,7 @@ struct elevator_queue *elevator_alloc(struct request_qu= eue *q, eq->type =3D e; kobject_init(&eq->kobj, &elv_ktype); mutex_init(&eq->sysfs_lock); + spin_lock_init(&eq->lock); hash_init(eq->hash); eq->et =3D et; =20 diff --git a/block/elevator.h b/block/elevator.h index c4d20155065e..4864add27136 100644 --- a/block/elevator.h +++ b/block/elevator.h @@ -119,13 +119,13 @@ struct request *elv_rqhash_find(struct request_queue = *q, sector_t offset); /* * each queue has an elevator_queue associated with it */ -struct elevator_queue -{ +struct elevator_queue { struct elevator_type *type; struct elevator_tags *et; void *elevator_data; struct kobject kobj; struct mutex sysfs_lock; + spinlock_t lock; unsigned long flags; DECLARE_HASHTABLE(hash, ELV_HASH_BITS); }; @@ -133,6 +133,33 @@ struct elevator_queue #define ELEVATOR_FLAG_REGISTERED 0 #define ELEVATOR_FLAG_DYING 1 #define ELEVATOR_FLAG_ENABLE_WBT_ON_EXIT 2 +#define ELEVATOR_FLAG_DISPATCH_IRQ 3 + +#define elevator_lock(e) spin_lock(&(e)->lock) +#define elevator_unlock(e) spin_unlock(&(e)->lock) +#define elevator_lock_irq(e) spin_lock_irq(&(e)->lock) +#define elevator_unlock_irq(e) spin_unlock_irq(&(e)->lock) +#define elevator_lock_irqsave(e, flags) \ + spin_lock_irqsave(&(e)->lock, flags) +#define elevator_unlock_irqrestore(e, flags) \ + spin_unlock_irqrestore(&(e)->lock, flags) +#define elevator_lock_assert_held(e) lockdep_assert_held(&(e)->lock) + +static inline void elevator_dispatch_lock(struct elevator_queue *eq) +{ + if (test_bit(ELEVATOR_FLAG_DISPATCH_IRQ, &eq->flags)) + elevator_lock_irq(eq); + else + elevator_lock(eq); +} + +static inline void elevator_dispatch_unlock(struct elevator_queue *eq) +{ + if (test_bit(ELEVATOR_FLAG_DISPATCH_IRQ, &eq->flags)) + elevator_unlock_irq(eq); + else + elevator_unlock(eq); +} =20 /* * block elevator interface --=20 2.39.2