linux-kernel - Re: [PATCH v4 00/40] lib/find: add atomic find

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Message-ID: <CAHk-=wiUTXC452qbypG3jW6XCZGfc8d-iehSavxn5JkQ=sv0zA@mail.gmail.com>
Date: Thu, 20 Jun 2024 11:00:38 -0700
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Yury Norov <yury.norov@...il.com>
Cc: linux-kernel@...r.kernel.org, "David S. Miller" <davem@...emloft.net>, 
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Subject: Re: [PATCH v4 00/40] lib/find: add atomic find_bit() primitives

On Thu, 20 Jun 2024 at 10:57, Yury Norov <yury.norov@...il.com> wrote:
>
>
> The typical lock-protected bit allocation may look like this:

If it looks like this, then nobody cares. Clearly the user in question
never actually cared about performance, and you SHOULD NOT then say
"let's optimize this that nobody cares about":.

Yury, I spend an inordinate amount of time just double-checking your
patches. I ended up having to basically undo one of them just days
ago.

New rule: before you send some optimization, you need to have NUMBERS.

Some kind of "look, this code is visible in profiles, so we actually care".

Because without numbers, I'm just not going to pull anything from you.
These insane inlines for things that don't matter need to stop.

And if they *DO* matter, you need to show that they matter.

               Linus