linux-kernel - Re: [PATCH RFC v2 0/7] blk-iocost: support to build iocost as kernel module

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Message-ID: <1775a296-6ce0-afaf-cf4a-2e7171966654@huaweicloud.com>
Date: Tue, 18 Jun 2024 16:03:04 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Christoph Hellwig <hch@...radead.org>, Yu Kuai <yukuai1@...weicloud.com>
Cc: axboe@...nel.dk, tj@...nel.org, gregkh@...uxfoundation.org,
 bvanassche@....org, josef@...icpanda.com, lizefan.x@...edance.com,
 hannes@...xchg.org, linux-block@...r.kernel.org,
 linux-kernel@...r.kernel.org, cgroups@...r.kernel.org, yi.zhang@...wei.com,
 yangerkun@...wei.com, "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH RFC v2 0/7] blk-iocost: support to build iocost as kernel
 module

Hi,

在 2024/06/18 15:12, Christoph Hellwig 写道:
> On Tue, Jun 18, 2024 at 11:17:44AM +0800, Yu Kuai wrote:
>> The motivation is that iocost is not used widely in our production, and
>> some customers don't want to increase kernel size to enable iocost that
>> they will never use, and it'll be painful to maintain a new downstream
>> kernel. Hence it'll be beneficially to build iocost as kernel module:
>>
>> - Kernel Size and Resource Usage, modules are loaded only when their
>> specific functionality is required.
>>
>> - Flexibility and Maintainability, allows for dynamic loading and unloading
>> of modules at runtime without the need to recompile and restart the kernel,
>> for example we can just replace blk-iocost.ko to fix iocost CVE in our
>> production environment.
> 
> Given the amount of new exports and infrastructure it adds this still
> feels like a bad tradeoff.

Yes, I understand your concern, let's see if we can export less and
hopefully accept the tradeoff. :) All other cgroup policies and wbt can
benefit the same without more helpers to be exported.

Thanks,
Kuai
> 
> 
> .
>