Re: [PATCH 1/2] Revert "mm: make faultaround produce old ptes"

[Michal Hocko]

On Thu 16-06-16 15:27:35, Kirill A. Shutemov wrote:
> On Thu, Jun 16, 2016 at 02:20:02PM +0200, Michal Hocko wrote:
> > On Tue 14-06-16 11:42:29, Kirill A. Shutemov wrote:
> > > This reverts commit 5c0a85fad949212b3e059692deecdeed74ae7ec7.
> > > 
> > > The commit causes ~6% regression in unixbench.
> > 
> > Is the regression fully explained? My understanding from the email
> > thread is that this is suspiciously too high. It is not like I would
> > be against the revert but having an explanation would be really
> > appreciated.
> 
> My understanding is that it's overhead on setting accessed bit:
> 
> http://lkml.kernel.org/r/20160613125248.GA30109@xxxxxxxxxxxxxxxxxx

But those numbers cannot explain the regression completely AFAIU. It
smells like something else is going on. Anyway, as I've said I do not
have anything against the revert just more than "unixbench regresses"
would be nice.
-- 
Michal Hocko
SUSE Labs