Re: [PATCH, RFC] block: always use a list_head for requests

[Jens Axboe <axboe@kernel.dk>]

On 6/12/25 1:42 AM, Christoph Hellwig wrote:
> Turn the remaining lists of requests into the standard doubly linked
> list.  This removes a lot of hairy list manipulation code and allows
> east reverse walking of the lists, which will be needed to improve
> merging.
> 
> XXX: the ublk queue_rqs code is pretty much broken here, because
> it's so different from the other drivers and I don't understand it.

First of all, we're definitely not doing this for 6.16-rc, and secondly
it'd need to be properly tested in terms of performance implications as
well.

I'm somewhat annoyed that ordered plug lists turned into this, which I
already strongly suspected would be the case back then. And doubly so
that a really basic performance regression was also caused by that, and
then the proposed "fix" is to go further into the "let's slow down the
fast path" of code. Yes deleting some code is nice, but let's not
pretend that it's free.

-- 
Jens Axboe