Received-SPF: pass (google.com: domain of linux-kernel+bounces-147818-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:40f1:3f00::1 as permitted sender) client-ip=2604:1380:40f1:3f00::1;
Subject: Re: [PATCH RFC v2 0/6] blk-throttle: support enable and disable
 during runtime
To: =?UTF-8?Q?Michal_Koutn=c3=bd?= <mkoutny@suse.com>,
 Yu Kuai <yukuai1@huaweicloud.com>
Cc: axboe@kernel.dk, chenhuacai@kernel.org, tj@kernel.org,
 josef@toxicpanda.com, jhs@mojatatu.com, svenjoac@gmx.de, raven@themaw.net,
 pctammela@mojatatu.com, qde@naccy.de, zhaotianrui@loongson.cn,
 linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
 loongarch@lists.linux.dev, cgroups@vger.kernel.org, yi.zhang@huawei.com,
 yangerkun@huawei.com, "yukuai (C)" <yukuai3@huawei.com>
References: <20240406080059.2248314-1-yukuai1@huaweicloud.com>
 <4exmes2ilp2cmfj3evf3jhhhq6tapfzgfzuasjejrxbj6a3327@3ecptofffblf>
From: Yu Kuai <yukuai1@huaweicloud.com>
Message-ID: <f721f06e-e2c8-608e-0dd0-41f41e948f0d@huaweicloud.com>
Date: Wed, 17 Apr 2024 09:09:07 +0800
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101
 Thunderbird/60.8.0
Precedence: bulk
MIME-Version: 1.0
In-Reply-To: <4exmes2ilp2cmfj3evf3jhhhq6tapfzgfzuasjejrxbj6a3327@3ecptofffblf>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit

Hi,

在 2024/04/16 23:56, Michal Koutný 写道:
> On Sat, Apr 06, 2024 at 04:00:53PM +0800, Yu Kuai <yukuai1@huaweicloud.com> wrote:
>> I'm planning to support build all blk-throttle polices as kernel module,
> 
> There is only one blk-throttle policy (especially after your removal of
> io.low). Did you mean blkcg policies in general?

Yes, bfq already support that, and others are all rq_qos based, they
will be much easier than blk-throtl.
> 
> The current code is complex because of various lifecycles in
> 	devices x cgroups.
> Turning policies into modules seems to make it
> 	devices x cgroups x policy modules
> .
> 
> Could you please add more info why policies as modules is beneficial,
> how to keep complexity capped?

First of all, users can only load these policies when they need, and
reduce kernel size; Then, when these policies is not loaded, IO fast
path will be slightly shorter, and save some memory overhead for each
disk.

Thanks,
Kuai

> 
> Thanks,
> Michal
>