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

[Yu Kuai <yukuai1@huaweicloud.com>]

Hi,

在 2024/06/14 0:15, Bart Van Assche 写道:
> On 6/12/24 10:54 PM, Greg KH wrote:
>> On Thu, Jun 13, 2024 at 09:49:30AM +0800, Yu Kuai wrote:
>>> From: Yu Kuai <yukuai3@huawei.com>
>>>
>>> Yu Kuai (7):
>>>    kernfs: export pr_cont_kernfs_path()
>>>    cgroup: export cgroup_parse_float
>>>    block: export some API
>>>    blk-iocost: factor out helpers to handle params from ioc_qos_write()
>>>    blk-iocost: parse params before initializing iocost
>>>    blk-iocost: support to free iocost
>>>    blk-iocost: support to build iocost as kernel module
>>
>> No where do you say _why_ building this as a module is a good idea.
>>
>> Why do this at all?
> 
> With CONFIG_BLK_CGROUP_IOCOST=y (as in the Android kernel), the
> blk-iocost kernel module causes a (small) runtime overhead, even if it
> is not being used.

I think this is not true... Because iocost is lazy initialized, and if
iocost is not initialized, there should not be such overhead.

Thanks,
Kuai

> 
> Thanks,
> 
> Bart.
> 
> 
> .
>