Re: [kernfs] ea7c5fc39a: stress-ng.stream.ops_per_sec 11827.2% improvement

[Greg Kroah-Hartman]

On Sat, Jun 06, 2020 at 11:52:16PM +0800, kernel test robot wrote:
> Greeting,
> 
> FYI, we noticed a 11827.2% improvement of stress-ng.stream.ops_per_sec due to commit:
> 
> 
> commit: ea7c5fc39ab005b501e0c7666c29db36321e4f74 ("[PATCH 1/4] kernfs: switch kernfs to use an rwsem")
> url: https://github.com/0day-ci/linux/commits/Ian-Kent/kernfs-proposed-locking-and-concurrency-improvement/20200525-134849
> 

Seriously?  That's a huge performance increase, and one that feels
really odd.  Why would a stress-ng test be touching sysfs?

thanks,

greg k-h