linux-kernel - Re: [f2fs-dev] [PATCH] f2fs: include non-compressed blocks in compr_written

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Message-ID: <16840026-35ba-cce6-4e0b-3332b0902d2a@kernel.org>
Date:   Wed, 13 Oct 2021 22:17:07 +0800
From:   Chao Yu <chao@...nel.org>
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] f2fs: include non-compressed blocks in
 compr_written_block

On 2021/10/12 0:02, Daeho Jeong wrote:
>>> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
>>> index c1bf9ad4c220..9b663eaf4805 100644
>>> --- a/fs/f2fs/compress.c
>>> +++ b/fs/f2fs/compress.c
>>> @@ -1530,6 +1530,7 @@ int f2fs_write_multi_pages(struct compress_ctx *cc,
>>>        if (cluster_may_compress(cc)) {
>>>                err = f2fs_compress_pages(cc);
>>>                if (err == -EAGAIN) {
>>> +                     add_compr_block_stat(cc->inode, cc->cluster_size);
>>
>> Shouldn't we relocate this after 'write' label?
>>
>> One more concern, it looks we've changed what compr_block stat indicated,
>> literally, the block we account should be compressed..., how about accounting
>> it by introducing .presist_blocks, used_blocks or occupied_blocks.... thoughts?
>>
> 
> What I wanted to add here is just one case in which compression was
> tried, but couldn't save any block, so gave up.
> If we put this below the "write" label, we will count blocks, even if
> the file is turned off for compression in "user-controlled
> compression" mode.
> Like the commit comment says, I want to estimate the overall compression rate.
> But, if we include every other compression disabled condition, it
> won't work like that.

Got it, thanks for the explanation.

Any thoughts about renaming compr_block? since some blocks accounted in
.compr_block weren't compressed blocks.

Thanks,

> 
> Thanks,
>