Re: [LKP] [cpuidle] 259231a045: will-it-scale.per_process_ops -12.6% regression

[Feng Tang]

On Tue, Dec 31, 2019 at 01:59:23PM +0800, Feng Tang wrote:
> Hi Marcelo,
> 
> On Wed, Sep 18, 2019 at 10:13:34AM +0800, kernel test robot wrote:
> > Greeting,
> > 
> > FYI, we noticed a -12.6% regression of will-it-scale.per_process_ops due to commit:
> > 
> > 
> > commit: 259231a045616c4101d023a8f4dcc8379af265a6 ("cpuidle: add poll_limit_ns to cpuidle_device structure")
> > https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next.git master
> 
> Any comments on this? We re-run the test for 5.5-rc1, and the regression remains.

Anyway, I found commit 259231a04 lost one "break" when moving
the original code, thus the semantics is changed to the last
enabled state's target_residency instead of the first enabled
one's.

I don't know if it's intentional, and I guess no, so here 
is a fix patch, please review, thanks

But even with this patch, the regression is still not recovered.

- Feng