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Subject: Re: [f2fs-dev] [PATCH v4] f2fs: introduce fragment allocation mode
 mount option
To:     Jaegeuk Kim <jaegeuk@kernel.org>
Cc:     Daeho Jeong <daeho43@gmail.com>,
        Daeho Jeong <daehojeong@google.com>, kernel-team@android.com,
        linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net
References: <20210902172404.3517626-1-daeho43@gmail.com>
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 <9f4a2954-e8c9-abc5-5df4-a7cec53433a3@kernel.org>
 <YUkR84sklj0SgosC@google.com>
From:   Chao Yu <chao@kernel.org>
Message-ID: <6c592379-104d-8975-4385-9778f23cda56@kernel.org>
Date:   Wed, 22 Sep 2021 23:23:39 +0800
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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,