Re: NUMA mempolicy /proc code in mainline shouldn't have been merged

[Christoph Lameter]

On Sat, 10 Sep 2005, Andrew Morton wrote:

> Andi Kleen <ak@xxxxxxx> wrote:
> >
> >  Just noticed the ugly SGI /proc/*/numa_maps code got merged.

Well its ugly because you said that the fixes to make it less ugly were 
"useless". I can still submit those fixes that make numa_maps a part of 
smaps and that cleanup the way policies are displayed.

> Been in -mm for over two months.
> 
> >  I argued several times against it

Nope you argued against changing memory policies via proc. The numa_maps 
patch is displaying on which node a vma uses memory.

> > and I very deliberately didn't include
> >  a similar facility when I wrote the NUMA policy code because it's a bad
> >  idea.

Thats the idea of changing memory policies right? NBot displaying memory 
usages across nodes?

> >  - it presents lots of kernel internal information and mempolicy
> >  internals (like how many people have a page mapped) etc.
> >  to userland that shouldn't be exposed to this.

Very important information. Somewhat similar information is already 
available via smaps.

> >  - the format is very complicated and the chance of bug free
> >  userland parsers of this is near zero.

What is complicated about the format? And the basic use is to see where 
memory for it was placed. I have code here that parses the format.

> >  - there is no demonstrated application that needs it
> >  (there was a theoretical usecase where it might be needed,
> >  but there were better solutions proposed for this) 

Could you be more specific? The application is to figure out how memory is 
placed. Just to cat /proc/<pid>/numa_maps. Seems to be a favorite with 
some people.

> >  Can the patch please be removed? 
> 
> OK by me.  I queued a revert patch.

No idea why that would be necessary.
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