Re: [LKP] Re: [x86/mce] 1de08dccd3: will-it-scale.per_process_ops -14.1% regression

Feng Tang
2020-08-24T15:48:40Z

On Mon, Aug 24, 2020 at 11:38:53PM +0800, Luck, Tony wrote:
> > Yes, that's what we suspected. And I just did another try to force the
> > percpu mce structure aligned. And the regression seems to be gone (reduced
> > from 14.1% to 2%), which further proved it.
>
> I wonder whether it would be useful for bisection of performance issues
> for you to change the global definition of DEFINE_PER_CPU() to make
> all per CPU definitions aligned. Just like you switch compiler flags to make
> all functions aligned.

Thanks for the hint! This will definitely help tracking strange performance
changes like this, as a general debug mthod.

Thanks,
Feng

>
> -Tony