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Date:   Thu, 13 Sep 2018 02:02:12 +0300
From:   Alexey Dobriyan <adobriyan@gmail.com>
To:     prakash.sangappa@oracle.com
Cc:     linux-kernel@vger.kernel.org, mhocko@kernel.org,
        dave.hansen@intel.com, cl@linux.com, khandual@linux.vnet.ibm.com
Subject: Re: [RFC PATCH] Add /proc/<pid>/numa_vamaps for numa node information
Message-ID: <20180912230212.GA6567@avx2>
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> 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.

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.

Text is harder than it looks.
Please in the name of everything holy add new honest system call.