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From: Daeho Jeong <daeho43@gmail.com>
To: Chao Yu <chao@kernel.org>
Cc: linux-kernel@vger.kernel.org,
	linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com,
	Daeho Jeong <daehojeong@google.com>
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: introduce fragment allocation mode mount option
Date: Fri, 27 Aug 2021 08:22:25 -0700	[thread overview]
Message-ID: <CACOAw_yhgo1_wrejKskSm=Rsw27ogx=TS_A=z=-NGLcecA-gYA@mail.gmail.com> (raw)
In-Reply-To: <1f1e6d38-6bd1-17ea-b8ca-a45d1244728f@kernel.org>

> I'd like to add a fixed chunk/hole fragmentation mode in addition, then
> userspace can control the fragmented chunk/hole with fixed size.
>
> How do you think of renaming "fragment:block" to "fragment:rand_block", and
> then I can add "fragment:fixed_block" option and its logic in addition?
>

The reason I added the randomness on these values is the segment
selection in SSR mode.
If all the segments have the same free block counts, f2fs will
allocate a new segment sequentially in SSR.
This was what I didn't want. Plus, in the real world, the size of hole
and chunk will be different in different segments.

But, if you think we need this "fragment:fixed_block" mode, I am happy
to have it. :)

> Do we need to consider multiple thread scenario? in such case,
> .fragment_remained_chunk may update randomly.
>
> In addition, multiple log headers share one .fragment_remained_chunk,
> it may cause unexpected result, it means there may be continuous holes
> or chunks in locality due to swithing between different log headers.
>
> Thanks,
>

Oh, I overlooked that point. I am going to add the variable for each
segment as you said before.

Thanks,

  reply	other threads:[~2021-08-27 15:22 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-25 18:57 Daeho Jeong
2021-08-27  5:26 ` [f2fs-dev] " Chao Yu
2021-08-27 15:22   ` Daeho Jeong [this message]
2021-08-28  0:43     ` Chao Yu
2021-08-30 17:27       ` Daeho Jeong

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