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

[Yin, Fengwei]

Hi Andrew, Shakeel,

On Tue, 2023-01-31 at 10:26 -0800, Shakeel Butt wrote:
> +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.
This performance regression still can be reproduced on latest master
branch. So we took option1 here. Right? Thanks.

Regards
Yin, Fengwei

> 
> thanks,
> Shakeel