Re: [PATCH 5.20 1/4] block: add bio_rewind() API

[Jens Axboe <axboe@kernel.dk>]

On 6/29/22 12:40 PM, Kent Overstreet wrote:
> On Wed, Jun 29, 2022 at 11:16:10AM -0600, Jens Axboe wrote:
>> Not sure what Christoph change you are referring to, but all the ones
>> that I did to improve the init side were all backed by numbers I ran at
>> that time (and most/all of the commit messages will have that data). So
>> yes, it is indeed still very noticeable. Maybe not at 100K IOPS, but at
>> 10M on a core it most certainly is.
> 
> I was referring to 609be1066731fea86436f5f91022f82e592ab456. You
> signed off on it, you must remember it...?

I'm sure we all remember each and every commit that gets applied,
particularly with such a precise description of the change.

>> I'm all for having solid and maintainable code, obviously, but frivolous
>> bloating of structures and more expensive setup cannot be hand waved
>> away with "it doesn't matter if we touch 3 or 6 cachelines" because we
>> obviously have a disagreement on that.
> 
> I wouldn't propose inflating struct _bio_ like that. But Jens, to be
> blunt - I know we have different priorities in the way we write code.
> Your writeback throttling code was buggy for _ages_ and I had users
> hitting deadlocks there that I pinged you about, and I could not make
> heads or tails of how that code was supposed to work and not for lack
> of time spent trying!

OK Kent, you just wasted your 2nd chance here. Plonk. There are many
rebuttals that could be made here, but I won't waste my time on it, nor
would it be appropriate.

Come back when you know how to act professionally. Or don't come back
at all.

-- 
Jens Axboe