Re: Fw: some questions about uploading a Linux kernel driver

[Song Liu <song@kernel.org>]

Hi Xiaosong,

On Wed, Apr 22, 2020 at 5:26 AM Xiaosong Ma <xma@qf.org.qa> wrote:
>
> Dear Song,
>
> This is Xiaosong Ma from Qatar Computing Research Institute. I am
> writing to follow up with the questions posed by a co-author from
> Tsinghua U, regarding upstreaming our alternative md implementation
> that is designed to significantly reduce SSD RAID latency (both median
> and tail) for large SSD pools (such as 20-disk or more).
>
> We read the Linux kernel upstreaming instructions, and believe that
> our implementation has excellent separability from the current code
> base (as a plug-and-play module with identical interfaces as md).

Plug-and-play is not the key for upstream new code/module. There are
some other keys to consider:

1. Why do we need it? (better performance is a good reason here).
2. What's the impact on existing users?
3. Can we improve existing code to achieve the same benefit?

> Meanwhile, we wonder whether there are standard test cases or
> preferred applications that we should test our system with, before
> doing code cleaning up. Your guidance is much appreciated.

For testing, "mdadm test" is a good starting point (if it works here).
We also need data integrity tests and stress tests.

Thanks,
Song