linux-kernel - Re: [f2fs-dev] [PATCH v2] f2fs: add sysfs nodes to get accumulated compression info

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Date:   Wed, 10 Mar 2021 09:31:01 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Daeho Jeong <daeho43@...il.com>
CC:     <linux-kernel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>,
        <kernel-team@...roid.com>, Daeho Jeong <daehojeong@...gle.com>
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: add sysfs nodes to get accumulated
 compression info

On 2021/3/9 21:00, Daeho Jeong wrote:
> 2021년 3월 9일 (화) 오후 6:22, Chao Yu <yuchao0@...wei.com>님이 작성:
>>
>> On 2021/3/5 10:24, Daeho Jeong wrote:
>>> From: Daeho Jeong <daehojeong@...gle.com>
>>>
>>> Added acc_compr_inodes to show accumulated compressed inode count and
>>> acc_compr_blocks to show accumulated secured block count with
>>
>> I noticed that these stat numbers are recorded in extra reserved area in
>> hot node curseg journal, the journal will be persisted only for umount
>> or fastboot checkpoint, so the numbers are not so accurate... does this
>> satisfy your requirement?
>>
> 
> Yes, we are satisfied with just getting rough number of them. But, it

Alright,

> would be better if you suggest more accurate way. :)

I think this is the cheapest way to store rough number, otherwise it needs to change
f2fs_checkpoint structure layout or add a new inner inode to persist these stat
numbers if we want more accurate one.

> 
>>> compression in sysfs. These can be re-initialized to "0" by writing "0"
>>> value in one of both.
>>
>> Why do we allow reset the stat numbers?
>>
> 
> Actually, I want to have a way to clear any stale number of them, but
> I agree we don't need this.
> 
>> Why not covering all code with macro CONFIG_F2FS_FS_COMPRESSION, since these
>> numbers are only be updated when we enable compression.
>>
> 
> I wanted to keep the info even in the kernel with doesn't support
> per-file compression if those had been written once. What do you
> think?

Sure, if so it's fine to me. :)

Thanks,

> 
>> Thanks,
> .
>