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@intel.com/ (local)

On Mon, Jan 30, 2023 at 9:57 PM Shakeel Butt [off-list ref]
wrote:

quoted

[...]

quoted

quoted

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