Re: [linux-next:master] [mm] 98c9daf5ae: aim7.jobs-per-min -29.4% regression

[Roman Gushchin <roman.gushchin@linux.dev>]

On Mon, Jul 15, 2024 at 10:14:31PM +0800, Oliver Sang wrote:
> hi, Roman Gushchin,
> 
> On Fri, Jul 12, 2024 at 07:03:31PM +0000, Roman Gushchin wrote:
> > On Fri, Jul 12, 2024 at 02:04:48PM +0800, kernel test robot wrote:
> > > 
> > > 
> > > Hello,
> > > 
> > > kernel test robot noticed a -29.4% regression of aim7.jobs-per-min on:
> > > 
> > > 
> > > commit: 98c9daf5ae6be008f78c07b744bcff7bcc6e98da ("mm: memcg: guard memcg1-specific members of struct mem_cgroup_per_node")
> > > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> > 
> > Hello,
> > 
> > thank you for the report!
> > 
> > I'd expect that the regression should be fixed by the commit
> > "mm: memcg: add cache line padding to mem_cgroup_per_node".
> > 
> > Can you, please, confirm that it's not the case?
> > 
> > Thank you!
> 
> in our this aim7 test, we found the performance partially recovered by
> "mm: memcg: add cache line padding to mem_cgroup_per_node" but not fully

Thank you for providing the detailed information!

Can you, please, check if the following patch resolves the regression entirely?

Thanks,
Roman

--

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 60418934827c..3aae347cda09 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -110,6 +110,7 @@ struct mem_cgroup_per_node {
        /* Fields which get updated often at the end. */
        struct lruvec           lruvec;
        unsigned long           lru_zone_size[MAX_NR_ZONES][NR_LRU_LISTS];
+       CACHELINE_PADDING(_pad2_);
        struct mem_cgroup_reclaim_iter  iter;
 };