Re: [LKP] [mm] 3484b2de949: -46.2% aim7.jobs-per-min

Huang Ying
2015-02-28T02:30:27Z

On Sat, 2015-02-28 at 01:46 +0000, Mel Gorman wrote:
> On Fri, Feb 27, 2015 at 03:21:36PM +0800, Huang Ying wrote:
> > FYI, we noticed the below changes on
> >
> > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > commit 3484b2de9499df23c4604a513b36f96326ae81ad ("mm: rearrange zone fields into read-only, page alloc, statistics and page reclaim lines")
> >
> > The perf cpu-cycles for spinlock (zone->lock) increased a lot. I suspect there are some cache ping-pong or false sharing.
> >
>
> Are you sure about this result? I ran similar tests here and found that
> there was a major regression introduced near there but it was commit
> 05b843012335 ("mm: memcontrol: use root_mem_cgroup res_counter") that
> cause the problem and it was later reverted. On local tests on a 4-node
> machine, commit 3484b2de9499df23c4604a513b36f96326ae81ad was within 1%
> of the previous commit and well within the noise.

I have double checked the result before sending out.

Do you do the test with same kernel config and test case/parameters
(aim7/page_test/load 6000)?

Best Regards,
Huang, Ying