Re: [RFC PATCH] Add /proc/<pid>/numa_vamaps for numa node information

[prakash.sangappa]

On 05/03/2018 11:03 AM, Christopher Lameter wrote:
> On Tue, 1 May 2018, Prakash Sangappa wrote:
>
> > For analysis purpose it is useful to have numa node information
> > corresponding mapped address ranges of the process. Currently
> > /proc/<pid>/numa_maps provides list of numa nodes from where pages are
> > allocated per VMA of the process. This is not useful if an user needs to
> > determine which numa node the mapped pages are allocated from for a
> > particular address range. It would have helped if the numa node information
> > presented in /proc/<pid>/numa_maps was broken down by VA ranges showing the
> > exact numa node from where the pages have been allocated.
> Cant you write a small script that scans the information in numa_maps and
> then displays the total pages per NUMA node and then a list of which
> ranges have how many pages on a particular node?

Don't think we can determine which numa node a given user process
address range has pages from, based on the existing 'numa_maps' file.

> > reading this file will not be restricted(i.e requiring CAP_SYS_ADMIN).
> So a prime motivator here is security restricted access to numa_maps?
No it is the opposite. A regular user should be able to determine
numa node information.