Re: [linus:master] [mm] f1a7941243: unixbench.score -19.2% regression

[Shakeel Butt]

+per-cpu memory maintainers for FYI.

Thread started at
https://lore.kernel.org/linux-mm/202301301057.e55dad5b-oliver.sang@xxxxxxxxx/

On Mon, Jan 30, 2023 at 9:57 PM Shakeel Butt <shakeelb@xxxxxxxxxx> wrote:
>
[...]
> >
> > We could cut down the number of calls to pcpu_alloc() by a factor of 4
> > by having a pcpu_alloc_bulk() that would allocate all four RSS counters
> > at once.
> >
> > Just throwing out ideas ...
>
> Thanks, I will take a stab at pcpu_alloc_bulk() and will share the
> result tomorrow.
>

OK, not a one day effort.

Andrew, which option do you prefer?

1. Keep the patches as the test workload (fork ping pong) is not a
representative of real world workload and work on improving
pcpu_alloc() for 6.4+.

2. Revert the patches for now, improve pcpu_alloc() and re-introduce
the patches once we confirm that fork-ping-pong is not regressed
anymore.

thanks,
Shakeel