Re: [PATCH md-6.9 00/10] md/raid1: refactor read_balance() and some minor fix

[Song Liu]

Hi Kuai and Paul,

On Thu, Feb 22, 2024 at 12:03 AM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:
>
> From: Yu Kuai <yukuai3@xxxxxxxxxx>
>
> The orignial idea is that Paul want to optimize raid1 read
> performance([1]), however, we think that the orignial code for
> read_balance() is quite complex, and we don't want to add more
> complexity. Hence we decide to refactor read_balance() first, to make
> code cleaner and easier for follow up.
>
> Before this patchset, read_balance() has many local variables and many
> braches, it want to consider all the scenarios in one iteration. The
> idea of this patch is to devide them into 4 different steps:
>
> 1) If resync is in progress, find the first usable disk, patch 5;
> Otherwise:
> 2) Loop through all disks and skipping slow disks and disks with bad
> blocks, choose the best disk, patch 10. If no disk is found:
> 3) Look for disks with bad blocks and choose the one with most number of
> sectors, patch 8. If no disk is found:
> 4) Choose first found slow disk with no bad blocks, or slow disk with
> most number of sectors, patch 7.

Thanks for your great work in this set. It looks great.

Please address feedback from folks and send v2. We can still get this in
6.9 merge window.

Thanks,
Song