Re: [mm] 2d146aa3aa: vm-scalability.throughput -36.4% regression

[Michal Koutný]

On Tue, Aug 31, 2021 at 02:30:36PM +0800, Feng Tang <feng.tang@xxxxxxxxx> wrote:
> Yes, I tried many re-arrangement of the members of cgroup_subsys_state,
> and even close members of memcg, but there were no obvious changes.
> What can recover the regresion is adding 128 bytes padding in the css,
> no matter at the start, end or in the middle.

Do you mean the padding added outside the .cgroup--.refcnt members area
also restores the benchmark results? (Or you refer to paddings that move
.cgroup and .refcnt across a cacheline border ?) I'm asking to be sure
we have correct understanding of what members are contended (what's the
frequent writer).

Thanks,
Michal