Thread (4 messages) 4 messages, 2 authors, 2011-09-23

Re: [RFC][PATCH] show page size in /proc/$pid/numa_maps

From: David Rientjes <rientjes@google.com>
Date: 2011-09-22 20:43:47
Also in: lkml

On Wed, 21 Sep 2011, Dave Hansen wrote:
The output of /proc/$pid/numa_maps is in terms of number of pages
like anon=22 or dirty=54.  Here's some output:

7f4680000000 default file=/hugetlb/bigfile anon=50 dirty=50 N0=50
7f7659600000 default file=/anon_hugepage\040(deleted) anon=50 dirty=50 N0=50
7fff8d425000 default stack anon=50 dirty=50 N0=50

Looks like we have a stack and a couple of anonymous hugetlbfs
areas page which both use the same amount of memory.  They don't.

The 'bigfile' uses 1GB pages and takes up ~50GB of space.  The
anon_hugepage uses 2MB pages and takes up ~100MB of space while
the stack uses normal 4k pages.  You can go over to smaps to
figure out what the page size _really_ is with KernelPageSize
or MMUPageSize.  But, I think this is a pretty nasty and
counterintuitive interface as it stands.

The following patch adds a pagemult= field.  It is placed only
in cases where the VMA's page size differs from the base kernel
page size.  I'm calling it pagemult to emphasize that it is
indended to modify the statistics output rather than _really_
show the page size that the kernel or MMU is using.
Why not just add a pagesize={4K,2M,1G,...} field for every output?

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