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

Andrew Morton
2005-09-11T00:59:33Z

Christoph Lameter <clameter@engr.sgi.com> wrote:
>
> On Sat, 10 Sep 2005, Andrew Morton wrote:
>
> > Andi Kleen <ak@suse.de> 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.

It would be useful to see these.

> > > - 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.
>

Important to whom? Kernel developers or userspace developers? If the
latter, what use do they actually make of it? Shouldn't it be documented?

> > > - 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.

If it's useful to application developers then fine. It it's only useful to
kernel developers then the argument is weakened. However there's still
quite a lot of development going on in this area, so there's still some
argument for having the monitoring ability in the mainline tree.