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Date:   Wed, 16 Feb 2022 10:09:08 +0800
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Subject: Re: [RFC V2 5/6] blk-ioprio: make ioprio pluggable and modular
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To:     Bart Van Assche <bvanassche@acm.org>, Jens Axboe <axboe@kernel.dk>
Cc:     hch@infradead.org, Josef Bacik <jbacik@fb.com>,
        Tejun Heo <tj@kernel.org>, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20220215123705.58968-1-jianchao.wan9@gmail.com>
 <20220215123705.58968-6-jianchao.wan9@gmail.com>
 <cb5677fc-01ac-f97f-ccf8-eb91505ad0e3@acm.org>
From:   Wang Jianchao <jianchao.wan9@gmail.com>
In-Reply-To: <cb5677fc-01ac-f97f-ccf8-eb91505ad0e3@acm.org>
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Precedence: bulk


On 2022/2/16 5:26 上午, Bart Van Assche wrote:
> On 2/15/22 04:37, Wang Jianchao (Kuaishou) wrote:
>> diff --git a/block/Makefile b/block/Makefile
>> index f38eaa612929..f6a3995af285 100644
>> --- a/block/Makefile
>> +++ b/block/Makefile
>> @@ -17,7 +17,8 @@ obj-$(CONFIG_BLK_DEV_BSGLIB)    += bsg-lib.o
>>   obj-$(CONFIG_BLK_CGROUP)    += blk-cgroup.o
>>   obj-$(CONFIG_BLK_CGROUP_RWSTAT)    += blk-cgroup-rwstat.o
>>   obj-$(CONFIG_BLK_DEV_THROTTLING)    += blk-throttle.o
>> -obj-$(CONFIG_BLK_CGROUP_IOPRIO)    += blk-ioprio.o
>> +io-prio-y             := blk-ioprio.o
>> +obj-$(CONFIG_BLK_CGROUP_IOPRIO)    += io-prio.o
>>   obj-$(CONFIG_BLK_CGROUP_IOLATENCY)    += blk-iolatency.o
>>   obj-$(CONFIG_BLK_CGROUP_IOCOST)    += blk-iocost.o
>>   obj-$(CONFIG_MQ_IOSCHED_DEADLINE)    += mq-deadline.o
> 
> Is the above change really necessary?

Except for making maintaining easier on a running system, removing a
rqos policy module with cgroup supporting can release a blk-cgroup
policy slots. As BLKCG_MAX_POLS, the max slots number is fixed now.

> 
>> +static int blk_ioprio_init(struct request_queue *q);
>>   static struct rq_qos_ops blkcg_ioprio_ops = {
> 
> Please insert a blank line between a function declaration and a structure definition.

Yes, I will do it in next version.

Thanks
Jianchao