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

From: Jens Axboe <axboe@kernel.dk>
To: Kent Overstreet <kent.overstreet@gmail.com>
Cc: "Martin K . Petersen" <martin.petersen@oracle.com>,
	Mike Snitzer <snitzer@redhat.com>,
	Eric Biggers <ebiggers@google.com>,
	Ming Lei <ming.lei@redhat.com>,
	linux-block@vger.kernel.org, dm-devel@redhat.com,
	Dmitry Monakhov <dmonakhov@openvz.org>
Subject: Re: [dm-devel] [PATCH 5.20 1/4] block: add bio_rewind() API
Date: Wed, 29 Jun 2022 14:51:48 -0600	[thread overview]
Message-ID: <788DCE4B-8992-436B-B0D4-D101E9176345@kernel.dk> (raw)
In-Reply-To: <20220629192646.aoj5c7xdqkifwjdg@moria.home.lan>

On Jun 29, 2022, at 1:26 PM, Kent Overstreet <kent.overstreet@gmail.com> wrote:
> 
> On Wed, Jun 29, 2022 at 01:00:52PM -0600, Jens Axboe wrote:
>>> 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, you're just acting like your code is immune to criticism, and I don't have
> an eyeroll big enough for that. We all know how you care about chasing every
> last of those 10 million iops - and not much else.

Kent, the time for your unsolicited opinions and attacks have passed. Just go away, not interested in interacting with you. You have no idea what you’re talking about. 

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