linux-kernel - Re: [f2fs-dev] [PATCH v4] f2fs: introduce fragment allocation mode mount option

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Date:   Wed, 22 Sep 2021 23:23:39 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
Cc:     Daeho Jeong <daeho43@...il.com>,
        Daeho Jeong <daehojeong@...gle.com>, kernel-team@...roid.com,
        linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH v4] f2fs: introduce fragment allocation mode
 mount option

On 2021/9/21 6:57, Jaegeuk Kim wrote:
> On 09/12, Chao Yu wrote:
>> On 2021/9/11 7:13, Jaegeuk Kim wrote:
>>> Wait. Why do we need to add so many options here? I was expecting to see
>>> performance difference when getting random segments or random blocks as
>>> an extreme case. I don't get the point why we need the middle of those cases.
>>
>> I guess we can simply the aging test procedure of filesystem by changing a bit
>> based on this patch.
> 
> My question was on "fragment:fixed_block".

This mode can be used for below filesystem aging scenario.

Fragmenting filesystem with specified pattern:
1M chunk | 1M hole | 1M chunk | 1M hole | ...

e.g.

Before
1. create/write 10 1M files: file0 file1 file2 ... file9
2. remove file1 file3 file5 ... file9

After
mode=fragment:fixed_block
fragment_chunk_size=1M
fragment_hole_size=1M
1. create/write one 10M file

Thanks,

> 
>>
>> See comments in below thread.
>>
>> https://lore.kernel.org/lkml/425daf77-8020-26ce-dc9f-019d9a881b78@kernel.org/
>>
>> Thanks,