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SubjectRe: [fsnotify] c738fbabb0: will-it-scale.per_process_ops -9.5% regression
On Fri, Jul 24, 2020 at 6:47 AM Amir Goldstein <amir73il@gmail.com> wrote:
>
> On Fri, Jul 24, 2020 at 5:45 AM Rong Chen <rong.a.chen@intel.com> wrote:
> >
> >
> >
> > On 7/21/20 11:59 PM, Amir Goldstein wrote:
> > > On Tue, Jul 21, 2020 at 3:15 AM kernel test robot <rong.a.chen@intel.com> wrote:
> > >> Greeting,
> > >>
> > >> FYI, we noticed a -9.5% regression of will-it-scale.per_process_ops due to commit:
> > >>
> > >>
> > >> commit: c738fbabb0ff62d0f9a9572e56e65d05a1b34c6a ("fsnotify: fold fsnotify() call into fsnotify_parent()")
> > > Strange, that's a pretty dumb patch moving some inlined code from one
> > > function to
> > > another (assuming there are no fsnotify marks in this test).
> > >
> > > Unless I am missing something the only thing that changes slightly is
> > > an extra d_inode(file->f_path.dentry) deference.
> > > I can get rid of it.
> > >
> > > Is it possible to ask for a re-test with fix patch (attached)?
> >
> > Hi Amir,
> >
> > We failed to apply this patch, could you tell us the base commit or the
> > base branch?
> >
>
> Hi Rong,
>
> The patch is applied on top of the reported offending commit:
> c738fbabb0ff62d0f9a9572e56e65d05a1b34c6a ("fsnotify: fold fsnotify()
> call into fsnotify_parent()")
>
> I pushed it to my github:
> https://github.com/amir73il/linux/commits/for_lkp
>

FWIW, I tried reproducing the reported regression on a local machine.

I ran the test twice on each of the branch commits:

26dc3d2bff62 fsnotify: pass inode to fsnotify_parent()
c738fbabb0ff fsnotify: fold fsnotify() call into fsnotify_parent()
71d734103edf fsnotify: Rearrange fast path to minimise overhead when
there is no watcher
47aaabdedf36 fanotify: Avoid softlockups when reading many events

Not only did I not observe a regression with the reported commit,
but there was a slight improvement. And then there yet was another
improvement with the fix commit on top of it.

But it could be that I am doing something wrong, because I have zero
millage with LKP.

=========================================================================================
compiler/cpufreq_governor/kconfig/mode/nr_task/rootfs/tbox_group/test/testcase:
gcc-7/performance/defconfig/process/16/ubuntu/amir-lkp/open1/will-it-scale

commit:
47aaabdedf366ac5894c7fddec388832f0d8193e
71d734103edfa2b4c6657578a3082ee0e51d767e
c738fbabb0ff62d0f9a9572e56e65d05a1b34c6a
26dc3d2bff623768cbbd0c8053ddd6390fd828d2

47aaabdedf366ac5 71d734103edfa2b4c6657578a30
c738fbabb0ff62d0f9a9572e56e 26dc3d2bff623768cbbd0c8053d
---------------- ---------------------------
--------------------------- ---------------------------
fail:runs %reproduction fail:runs %reproduction
fail:runs %reproduction fail:runs
| | | | |
| |
45:2 -555% 34:2 -807% 29:2
-996% 25:2 dmesg.timestamp:last
45:2 -555% 34:2 -807% 29:2
-996% 25:2 kmsg.timestamp:last
%stddev %change %stddev %change
%stddev %change %stddev
\ | \ | \
| \
1097404 +1.7% 1116452 +2.7% 1126533
+3.5% 1135663 will-it-scale.16.processes
0.02 ± 60% +20.0% 0.03 ± 66% +20.0% 0.03 ±
66% -20.0% 0.02 ± 50% will-it-scale.16.processes_idle
68587 +1.7% 69778 +2.7% 70408
+3.5% 70978 will-it-scale.per_process_ops


Thanks,
Amir.

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