On Sat, Mar 4, 2023 at 1:01 PM Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> It's still completely untested. Treat this very much as a "Let's make
> the common cases faster, at least for !MAXSMP".
Ok, so I started "testing" it in the sense that I actually looked at
the code it generated, and went all "why didn't it make any
difference".
And that's because the patch had the
#ifdef CONFIG_CPUMASK_OFFSTACK
condition exactly the wrong way around.
So if somebody actually wants to play with that patch, you need to
change that to be
#ifndef CONFIG_CPUMASK_OFFSTACK
(and then you obviously need to have a kernel config that does *not*
have MAXSMP set).
That at least simplifies some of the code generation when I look at
it. Whether the end result _works_ or not, I still haven't checked.
That patch is still very much meant as a "look, something like this
should make our cpumask handling much more efficient"
Linus
