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

[Chao Yu]

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@xxxxxxxxxx/
> >
> > Thanks,