lkml.org 
[lkml]   [2017]   [Jul]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC] mm/mremap: Remove redundant checks inside vma_expandable()
On Tue 11-07-17 08:26:40, Vlastimil Babka wrote:
> On 07/11/2017 08:03 AM, Michal Hocko wrote:
> > On Tue 11-07-17 09:58:42, Anshuman Khandual wrote:
> >>> here. This is hardly something that would save many cycles in a
> >>> relatively cold path.
> >>
> >> Though I have not done any detailed instruction level measurement,
> >> there is a reduction in real and system amount of time to execute
> >> the test with and without the patch.
> >>
> >> Without the patch
> >>
> >> real 0m2.100s
> >> user 0m0.162s
> >> sys 0m1.937s
> >>
> >> With this patch
> >>
> >> real 0m0.928s
> >> user 0m0.161s
> >> sys 0m0.756s
> >
> > Are you telling me that two if conditions cause more than a second
> > difference? That sounds suspicious.
>
> It's removing also a call to get_unmapped_area(), AFAICS. That means a
> vma search?

Ohh, right. I have somehow missed that. Is this removal intentional? The
changelog is silent about it.

--
Michal Hocko
SUSE Labs

\
 
 \ /
  Last update: 2017-07-11 08:51    [W:0.085 / U:0.216 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site