linux-kernel - Re: [PATCH RFC md-6.16 v3 00/19] md: introduce a new lockless bitmap

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Message-ID: <934fdd89-3963-98d5-b450-f36024aa47b2@huaweicloud.com>
Date: Mon, 12 May 2025 21:41:36 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Christoph Hellwig <hch@....de>, Yu Kuai <yukuai1@...weicloud.com>
Cc: xni@...hat.com, colyli@...nel.org, agk@...hat.com, snitzer@...nel.org,
 mpatocka@...hat.com, song@...nel.org, linux-kernel@...r.kernel.org,
 dm-devel@...ts.linux.dev, linux-raid@...r.kernel.org, yi.zhang@...wei.com,
 yangerkun@...wei.com, johnny.chenyi@...wei.com,
 "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH RFC md-6.16 v3 00/19] md: introduce a new lockless bitmap

Hi,

在 2025/05/12 21:27, Christoph Hellwig 写道:
> On Mon, May 12, 2025 at 04:40:02PM +0800, Yu Kuai wrote:
>> I don't have such plan for now, actually I tend to remove bitmap file,
>> once llbitmap is ready with lightweight overhead, I expect perforamce
>> can be better than old bitmap with bitmap file.
>>
>> If there are cases that llbitmap performace is still much worse than
>> none bitmap, and bitmap file can reduce the gap, we'll probable think
>> about bitmap file again.
> 
> I'd really love to see this replace the old code as soon as possible.
> But can we simply drop support for users with the bitmap in a file
> in the file system (no matter how much I dislike that use case..)?
> 

Do you mean drop it now?

AFAIK, bitmap file in a file system is problem the only case for now, I
don't see any users pass in a raw disk in this case, because bitmap file
is at most 128k by default.

Thanks,
Kuai

> .
>