lkml.org 
[lkml]   [2015]   [Dec]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] arm64: calculate the various pages number to show
On Fri, Nov 27, 2015 at 09:52:16AM +0800, Xishi Qiu wrote:
> On 2015/11/26 23:49, Mark Rutland wrote:
>
> > On Thu, Nov 26, 2015 at 11:05:32PM +0800, zhong jiang wrote:
> >> On 2015/11/25 23:04, Mark Rutland wrote:
> >>> On Wed, Nov 25, 2015 at 09:41:12PM +0800, zhongjiang wrote:
> >>>> This patch add the interface to show the number of 4KB or 64KB page,
> >>>> aims to statistics the number of different types of pages.
> >>>
> >>> What is this useful for? Why do we want it?
> >>>
> >>> What does it account for, just the swapper?
> >>>
> >>
> >> The patch is wirtten when I was in backport set_memory_ro. It can be used to
> >> detect whether there is a large page spliting and merging. large page will
> >> significantly reduce the TLB miss, and improve the system performance.
> >
> > Ok, but typically the user isn't going to be able to do much with this
> > information. It feels more like something that should be in the page
> > table dump code (where we can calculate the values as we walk the
> > tables).
> >
> > What is it intended to account for?
> >
> > The entire swapper?
> >
> > Just the linear mapping?
>
> Hi Mark,
>
> x86 has this information when cat /proc/meminfo, so how about just
> like x86 to show it?

The fact that another architecture has some implementation doesn't
necessarily mean it's a good idea. In this case there are concerns that
don't apply to x86, in that we support a number of page sizes, and
anything reading this needs to handle that fact.

If there's a sensible use-case, then I am not opposed to this. I don't
see the point in adding it just because we can.

A prerequisite for adding it is knowing precisely what it is intended to
describe. Otherwise it's impossible to review.

Thanks,
Mark.


\
 
 \ /
  Last update: 2015-12-03 19:41    [W:0.309 / U:0.152 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site