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

[prakash.sangappa]

On 09/12/2018 04:02 PM, Alexey Dobriyan wrote:
> > The /proc/pid/numa_vamaps shows mapped address ranges to numa node id
> > from where the physical pages are allocated.
> All these files make the problem with useless dentry and /proc/*/* inode
> instantiations worse (unlike top level /proc/* files which are
> tolerable).
>
> > +address-range	numa-node-id
> > +
> > +00400000-00410000 N1
> > +00410000-0047f000 N0
> > +0047f000-00480000 N2
> > +00480000-00481000 -
> > +00481000-004a0000 N0
> > +004a0000-004a2000 -
> > +004a2000-004aa000 N2
> > +004aa000-004ad000 N0
> > +004ad000-004ae000 -
> 'N' is useless data.

'N' could be dropped.

> Parsing with awk won't work because field #3 is separated with space
> but field #2 with '-'.
>
> %08lx-%08lx kind of sucks: 32-bit get aligned data so parsing can be
> faster by pointing to &p[8+1] but not on 64-bit.
> If scanf("%lx-%lx") is used then leading zeroes are useless.

This was similar to how '/proc/*/maps' file presents the  address range.
However, we could separate start and end address of the range with a
space, if that would be preferred.

> Text is harder than it looks.

We could make each line fixed length.  It could be  "%016lx %016lx %04d"
i.e 4 digit for node number?

> Please in the name of everything holy add new honest system call.