Re: [PATCH RFC -next 00/26] md/md-bitmap: introduce bitmap_operations

[Yu Kuai]

在 2024/08/13 15:21, Christoph Hellwig 写道:
> On Sat, Aug 10, 2024 at 10:08:28AM +0800, Yu Kuai wrote:
> > From: Yu Kuai <yukuai3@xxxxxxxxxx>
> >
> > The background is that currently bitmap is using a global spin_lock,
> > cauing lock contention and huge IO performance degration for all raid
> > levels.
> >
> > However, it's impossible to implement a new lock free bitmap with
> > current situation that md-bitmap exposes the internal implementation
> > with lots of exported apis. Hence bitmap_operations is invented, to
> > describe bitmap core implementation, and a new bitmap can be introduced
> > with a new bitmap_operations, we only need to switch to the new one
> > during initialization.
> >
> > And with this we can build bitmap as kernel module, but that's not
> > our concern for now.
> >
> > Noted I just compile this patchset, not tested yet.
>
> Refactoring the bitmap code to be modular seems like a good idea.
>
> But I'd just turn this into plain function calls and maybe a hidden
> data structure if you feel really fancy.  No need to introduce expensive
> indirect calls and a separate module.

Got it, and will make the struct bitmap a hidden structure in the next
version. This is exactly what I'm doing now locally, get rid of bitmap
direct dereference :).

Thanks for the review!
Kuai
> .