Re: [LKP] Re: [mm/memcg] bd0b230fe1: will-it-scale.per_process_ops -22.7% regression

[Xing Zhengjun]

On 11/2/2020 6:02 PM, Michal Hocko wrote:
> On Mon 02-11-20 17:53:14, Rong Chen wrote:
> > On 11/2/20 5:27 PM, Michal Hocko wrote:
> > > On Mon 02-11-20 17:15:43, kernel test robot wrote:
> > > > Greeting,
> > > >
> > > > FYI, we noticed a -22.7% regression of will-it-scale.per_process_ops due to commit:
> > > >
> > > >
> > > > commit: bd0b230fe14554bfffbae54e19038716f96f5a41 ("mm/memcg: unify swap and memsw page counters")
> > > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> > > I really fail to see how this can be anything else than a data structure
> > > layout change. There is one counter less.
> > >
> > > btw. are cgroups configured at all? What would be the configuration?
> >
> > Hi Michal,
> >
> > We used the default configure of cgroups, not sure what configuration you
> > want,
> > could you give me more details? and here is the cgroup info of will-it-scale
> > process:
> >
> > $ cat /proc/3042/cgroup
> > 12:hugetlb:/
> > 11:memory:/system.slice/lkp-bootstrap.service
>
> OK, this means that memory controler is enabled and in use. Btw. do you
> get the original performance if you add one phony page_counter after the
> union?
I add one phony page_counter after the union and re-test, the regression 
reduced to -1.2%. It looks like the regression caused by the data 
structure layout change.

=========================================================================================
tbox_group/testcase/rootfs/kconfig/compiler/nr_task/mode/test/cpufreq_governor/ucode/debug-setup:

lkp-hsw-4ex1/will-it-scale/debian-10.4-x86_64-20200603.cgz/x86_64-rhel-8.3/gcc-9/50%/process/page_fault2/performance/0x16/test1

commit:
  8d387a5f172f26ff8c76096d5876b881dec6b7ce
  bd0b230fe14554bfffbae54e19038716f96f5a41
  b3233916ab0a883e1117397e28b723bd0e4ac1eb (debug patch add one phony 
page_counter after the union)

8d387a5f172f26ff bd0b230fe14554bfffbae54e190 b3233916ab0a883e1117397e28b
---------------- --------------------------- ---------------------------
         %stddev     %change         %stddev     %change         %stddev
             \          |                \          |                \
    187632           -22.8%     144931            -1.2%     185391 
   will-it-scale.per_process_ops
  13509525           -22.8%   10435073            -1.2%   13348181 
   will-it-scale.workload



--
Zhengjun Xing