From mboxrd@z Thu Jan 1 00:00:00 1970 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 84F8625F7B4; Thu, 31 Jul 2025 07:14:15 +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=1753946059; cv=none; b=b3Rw6f101fVSKt5G1HfAYdy8KSHSQPI7QIcD+Sqr3LBkxTzAjtbTkFHsWHjoMgU8GDxDknStxiNCOB6Cjh+cOoWsO6ZZBJeyjdmmYiZgOs2Rf6hQuTPFQ3MexNsn1NbZEqa06PTx2wV9FNSOFtghpWN5/uwc7zwG3ddEFZc9v4E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753946059; c=relaxed/simple; bh=r7jURrF6I5tBL8grNAQw88uKKLsBi8rIxDnW6t0DDv0=; h=Subject:To:Cc:References:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=JsUzM/aZ+bW82bfUpouFIQ92RS+UWank9nmchFmNsGWMUedJBtY+v+ElIyaCY3FQ9o7WrZ3ySaQ3fz3j6/E8UTaoeJtBnroCSh3rZ6LOfxNorTdH87yxXPWc7nVACe+hKZ/gr9GHL0lymDb0jX9T9wno+dErxJaoN9QGYNSHe08= 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 [172.19.163.216]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4bt0gm2NPYzKHMtL; Thu, 31 Jul 2025 15:14:12 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 3F63C1A1478; Thu, 31 Jul 2025 15:14:11 +0800 (CST) Received: from [10.174.179.143] (unknown [10.174.179.143]) by APP4 (Coremail) with SMTP id gCh0CgDHjxC_F4tooJxPCA--.62453S3; Thu, 31 Jul 2025 15:14:09 +0800 (CST) Subject: Re: [PATCH v2 2/5] mq-deadline: switch to use elevator lock To: Damien Le Moal , Yu Kuai , Hannes Reinecke , jack@suse.cz, tj@kernel.org, josef@toxicpanda.com, axboe@kernel.dk Cc: cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com, "yukuai (C)" References: <20250730082207.4031744-1-yukuai1@huaweicloud.com> <20250730082207.4031744-3-yukuai1@huaweicloud.com> <750643e5-9f24-4e4c-8270-e421a03cf463@suse.de> <226d1cd7-bd35-4773-8f1c-d03f9c870133@kernel.org> <9d918e77-73ef-41ad-87cf-cf87803041b5@kernel.org> From: Yu Kuai Message-ID: <2ada440d-5121-6c3e-71db-1f8eb63864a7@huaweicloud.com> Date: Thu, 31 Jul 2025 15:14:06 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <9d918e77-73ef-41ad-87cf-cf87803041b5@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID:gCh0CgDHjxC_F4tooJxPCA--.62453S3 X-Coremail-Antispam: 1UD129KBjvJXoW3GrWkuF15Xr18Zw1UWr45Wrg_yoW7CrW7pr 4kKFW5JrWrJrn7Xr1qgr4UZry5tw4UJw1DXr1fJay8JFsrtFnIgr4UXr1v9r1DJr4fGrn8 JF1UXrZxuF17Jr7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBF14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_Jrv_JF1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvEwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7CjxVA2Y2ka 0xkIwI1lc7I2V7IY0VAS07AlzVAYIcxG8wCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x 0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E 7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcV C0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF 04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7 CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JUpwZcUUUUU= X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ Hi, 在 2025/07/31 15:04, Damien Le Moal 写道: > On 7/31/25 3:32 PM, Yu Kuai wrote: >> Hi, >> >> 在 2025/07/31 14:22, Damien Le Moal 写道: >>> On 7/31/25 3:20 PM, Hannes Reinecke wrote: >>>> On 7/30/25 10:22, Yu Kuai wrote: >>>>> From: Yu Kuai >>>>> >>>>> Replace the internal spinlock 'dd->lock' with the new spinlock in >>>>> elevator_queue, there are no functional changes. >>>>> >>>>> Signed-off-by: Yu Kuai >>>>> --- >>>>>    block/mq-deadline.c | 58 +++++++++++++++++++++------------------------ >>>>>    1 file changed, 27 insertions(+), 31 deletions(-) >>>>> >>>>> diff --git a/block/mq-deadline.c b/block/mq-deadline.c >>>>> index 9ab6c6256695..2054c023e855 100644 >>>>> --- a/block/mq-deadline.c >>>>> +++ b/block/mq-deadline.c >>>>> @@ -101,7 +101,7 @@ struct deadline_data { >>>>>        u32 async_depth; >>>>>        int prio_aging_expire; >>>>>    -    spinlock_t lock; >>>>> +    spinlock_t *lock; >>>>>    }; >>>>>      /* Maps an I/O priority class to a deadline scheduler priority. */ >>>>> @@ -213,7 +213,7 @@ static void dd_merged_requests(struct request_queue *q, >>>>> struct request *req, >>>>>        const u8 ioprio_class = dd_rq_ioclass(next); >>>>>        const enum dd_prio prio = ioprio_class_to_prio[ioprio_class]; >>>>>    -    lockdep_assert_held(&dd->lock); >>>>> +    lockdep_assert_held(dd->lock); >>>>>          dd->per_prio[prio].stats.merged++; >>>>>    @@ -253,7 +253,7 @@ static u32 dd_queued(struct deadline_data *dd, enum >>>>> dd_prio prio) >>>>>    { >>>>>        const struct io_stats_per_prio *stats = &dd->per_prio[prio].stats; >>>>>    -    lockdep_assert_held(&dd->lock); >>>>> +    lockdep_assert_held(dd->lock); >>>>>          return stats->inserted - atomic_read(&stats->completed); >>>>>    } >>>>> @@ -323,7 +323,7 @@ static struct request *__dd_dispatch_request(struct >>>>> deadline_data *dd, >>>>>        enum dd_prio prio; >>>>>        u8 ioprio_class; >>>>>    -    lockdep_assert_held(&dd->lock); >>>>> +    lockdep_assert_held(dd->lock); >>>>>          if (!list_empty(&per_prio->dispatch)) { >>>>>            rq = list_first_entry(&per_prio->dispatch, struct request, >>>>> @@ -434,7 +434,7 @@ static struct request >>>>> *dd_dispatch_prio_aged_requests(struct deadline_data *dd, >>>>>        enum dd_prio prio; >>>>>        int prio_cnt; >>>>>    -    lockdep_assert_held(&dd->lock); >>>>> +    lockdep_assert_held(dd->lock); >>>>>          prio_cnt = !!dd_queued(dd, DD_RT_PRIO) + !!dd_queued(dd, >>>>> DD_BE_PRIO) + >>>>>               !!dd_queued(dd, DD_IDLE_PRIO); >>>>> @@ -466,10 +466,9 @@ static struct request *dd_dispatch_request(struct >>>>> blk_mq_hw_ctx *hctx) >>>>>        struct request *rq; >>>>>        enum dd_prio prio; >>>>>    -    spin_lock(&dd->lock); >>>>>        rq = dd_dispatch_prio_aged_requests(dd, now); >>>>>        if (rq) >>>>> -        goto unlock; >>>>> +        return rq; >>>>>          /* >>>>>         * Next, dispatch requests in priority order. Ignore lower priority >>>>> @@ -481,9 +480,6 @@ static struct request *dd_dispatch_request(struct >>>>> blk_mq_hw_ctx *hctx) >>>>>                break; >>>>>        } >>>>>    -unlock: >>>>> -    spin_unlock(&dd->lock); >>>>> - >>>>>        return rq; >>>>>    } >>>>>    @@ -538,9 +534,9 @@ static void dd_exit_sched(struct elevator_queue *e) >>>>>            WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_READ])); >>>>>            WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_WRITE])); >>>>>    -        spin_lock(&dd->lock); >>>>> +        spin_lock(dd->lock); >>>>>            queued = dd_queued(dd, prio); >>>>> -        spin_unlock(&dd->lock); >>>>> +        spin_unlock(dd->lock); >>>>>              WARN_ONCE(queued != 0, >>>>>                  "statistics for priority %d: i %u m %u d %u c %u\n", >>>> >>>> Do you still need 'dd->lock'? Can't you just refer to the lock from the >>>> elevator_queue structure directly? >>> >>> Indeed. Little inline helpers for locking/unlocking q->elevator->lock would be >>> nice. >> >> How about the first patch to factor out inline helpers like dd_lock() >> and dd_unlock(), still use dd->lock without any functional changes, and >> then switch to use q->elevator->lock in the next patch? (same for bfq) > > Patch one can introduce elv->lock and the helpers, then patch 2 use the helpers > to replace dd->lock. Just don't say "no functional change" in the commit > message and rather explain that things keep working the same way as before, but > using a different lock. That will address Bart's comment too. > And same for bfq in patch 3. > Ok, this is what I did in the first RFC version: https://lore.kernel.org/all/20250530080355.1138759-3-yukuai1@huaweicloud.com/ I somehow convince myself using dd->lock is better. :( Will change this in the next version. Thanks, Kuai >