Re: [LKP] [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement

[Lu, Aaron]

On Mon, 2018-05-28 at 14:03 +0200, Michal Hocko wrote:
> On Mon 28-05-18 19:40:19, kernel test robot wrote:
> > 
> > Greeting,
> > 
> > FYI, we noticed a +23.0% improvement of vm-scalability.throughput due to commit:
> > 
> > 
> > commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol: implement memory.swap.events")
> > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> 
> This doesn't make any sense to me. The patch merely adds an accounting.
> It doesn't optimize anything. So I strongly suspect the result is just
> misleading or the test (environment) misconfigured. Not the first time
> I am seeing something like that I am afraid.
> 

Most likely the same situation as:
"
FYI, we noticed a -27.2% regression of will-it-scale.per_process_ops
due to commit:


commit: e27be240df53f1a20c659168e722b5d9f16cc7f4 ("mm: memcg: make sure
memory.events is uptodate when waking pollers")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
"

Where the performance change is due to layout change of
'struct mem_cgroup':
http://lkml.kernel.org/r/20180528085201.GA2918@xxxxxxxxx