# Re: \[PATCH V4 0/2\] mm: FAULT\_AROUND\_ORDER patchset performance data for powerpc

- From: Andrew Morton \<akpm@linux-foundation.org\>
- Date: 2014-05-20 07:32:25 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2014/05/4256560
- Thread: https://ratatoskr.run/linuxppc-dev/2014/05/4248701/t.md

```text
On Tue, 20 May 2014 15:52:07 +0930 Rusty Russell [ref] wrote:

> "Kirill A. Shutemov" [ref] writes:
> > Andrew Morton wrote:
> >> On Mon, 19 May 2014 16:23:07 -0700 (PDT) Hugh Dickins [ref] wrote:
> >> 
> >> > Shouldn't FAULT_AROUND_ORDER and fault_around_order be changed to be
> >> > the order of the fault-around size in bytes, and fault_around_pages()
> >> > use 1UL << (fault_around_order - PAGE_SHIFT)
> >> 
> >> Yes.  And shame on me for missing it (this time!) at review.
> >> 
> >> There's still time to fix this.  Patches, please.
> >
> > Here it is. Made at 3.30 AM, build tested only.
> 
> Prefer on top of Maddy's patch which makes it always a variable, rather
> than CONFIG_DEBUG_FS.  It's got enough hair as it is.
> 

We're at 3.15-rc5 and this interface should be finalised for 3.16.  So
Kirrill's patch is pretty urgent and should come first.

Well.  It's only a debugfs interface at this stage so we are allowed to
change it later, but it's better not to.
```