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

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Message-ID: <CAHk-=wjv-DkukaKb7f04WezyPjRERp=xfxv34j5fA8cDQ_JudA@mail.gmail.com>
Date: Thu, 20 Jun 2024 12:26:18 -0700
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Yury Norov <yury.norov@...il.com>
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Subject: Re: [PATCH v4 00/40] lib/find: add atomic find_bit() primitives

On Thu, 20 Jun 2024 at 11:32, Yury Norov <yury.norov@...il.com> wrote:
>
> Is that in master already? I didn't get any email, and I can't find
> anything related in the master branch.

It's 5d272dd1b343 ("cpumask: limit FORCE_NR_CPUS to just the UP case").

> > New rule: before you send some optimization, you need to have NUMBERS.
>
> I tried to underline that it's not a performance optimization at my
> best.

If it's not about performance, then it damn well shouldn't be 90%
inline functions in a header file.

If it's a helper function, it needs to be a real function elsewhere. Not this:

 include/linux/find_atomic.h                  | 324 +++++++++++++++++++

because either performance really matters, in which case you need to
show profiles, or performance doesn't matter, in which case it damn
well shouldn't have special cases for small bitsets that double the
size of the code.

              Linus