From: Andrew Morton <akpm@linux-foundation.org>
To: Prakash Sangappa <prakash.sangappa@oracle.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-api@vger.kernel.org, mhocko@suse.com,
kirill.shutemov@linux.intel.com, n-horiguchi@ah.jp.nec.com,
drepper@gmail.com, rientjes@google.com,
Naoya Horiguchi <nao.horiguchi@gmail.com>,
Dave Hansen <dave.hansen@intel.com>
Subject: Re: [RFC PATCH] Add /proc/<pid>/numa_vamaps for numa node information
Date: Wed, 2 May 2018 14:33:23 -0700 [thread overview]
Message-ID: <20180502143323.1c723ccb509c3497050a2e0a@linux-foundation.org> (raw)
In-Reply-To: <1525240686-13335-1-git-send-email-prakash.sangappa@oracle.com>
On Tue, 1 May 2018 22:58:06 -0700 Prakash Sangappa <prakash.sangappa@oracle.com> 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.
>
> The format of /proc/<pid>/numa_maps file content is dependent on
> /proc/<pid>/maps file content as mentioned in the manpage. i.e one line
> entry for every VMA corresponding to entries in /proc/<pids>/maps file.
> Therefore changing the output of /proc/<pid>/numa_maps may not be possible.
>
> Hence, this patch proposes adding file /proc/<pid>/numa_vamaps which will
> provide proper break down of VA ranges by numa node id from where the mapped
> pages are allocated. For Address ranges not having any pages mapped, a '-'
> is printed instead of numa node id. In addition, this file will include most
> of the other information currently presented in /proc/<pid>/numa_maps. The
> additional information included is for convenience. If this is not
> preferred, the patch could be modified to just provide VA range to numa node
> information as the rest of the information is already available thru
> /proc/<pid>/numa_maps file.
>
> Since the VA range to numa node information does not include page's PFN,
> reading this file will not be restricted(i.e requiring CAP_SYS_ADMIN).
>
> Here is the snippet from the new file content showing the format.
>
> 00400000-00401000 N0=1 kernelpagesize_kB=4 mapped=1 file=/tmp/hmap2
> 00600000-00601000 N0=1 kernelpagesize_kB=4 anon=1 dirty=1 file=/tmp/hmap2
> 00601000-00602000 N0=1 kernelpagesize_kB=4 anon=1 dirty=1 file=/tmp/hmap2
> 7f0215600000-7f0215800000 N0=1 kernelpagesize_kB=2048 dirty=1 file=/mnt/f1
> 7f0215800000-7f0215c00000 - file=/mnt/f1
> 7f0215c00000-7f0215e00000 N0=1 kernelpagesize_kB=2048 dirty=1 file=/mnt/f1
> 7f0215e00000-7f0216200000 - file=/mnt/f1
> ..
> 7f0217ecb000-7f0217f20000 N0=85 kernelpagesize_kB=4 mapped=85 mapmax=51
> file=/usr/lib64/libc-2.17.so
> 7f0217f20000-7f0217f30000 - file=/usr/lib64/libc-2.17.so
> 7f0217f30000-7f0217f90000 N0=96 kernelpagesize_kB=4 mapped=96 mapmax=51
> file=/usr/lib64/libc-2.17.so
> 7f0217f90000-7f0217fb0000 - file=/usr/lib64/libc-2.17.so
> ..
>
> The 'pmap' command can be enhanced to include an option to show numa node
> information which it can read from this new proc file. This will be a
> follow on proposal.
I'd like to hear rather more about the use-cases for this new
interface. Why do people need it, what is the end-user benefit, etc?
> There have been couple of previous patch proposals to provide numa node
> information based on pfn or physical address. They seem to have not made
> progress. Also it would appear reading numa node information based on PFN
> or physical address will require privileges(CAP_SYS_ADMIN) similar to
> reading PFN info from /proc/<pid>/pagemap.
>
> See
> https://marc.info/?t=139630938200001&r=1&w=2
>
> https://marc.info/?t=139718724400001&r=1&w=2
OK, let's hope that these people will be able to provide their review,
feedback, testing, etc. You missed a couple (Dave, Naoya).
> fs/proc/base.c | 2 +
> fs/proc/internal.h | 3 +
> fs/proc/task_mmu.c | 299 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
Some Documentation/ updates seem appropriate. I suggest you grep the
directory for "numa_maps" to find suitable locations.
And a quick build check shows that `size fs/proc/task_mmu.o' gets quite
a bit larger when CONFIG_SMP=n and CONFIG_NUMA=n. That seems wrong -
please see if you can eliminate the bloat from systems which don't need
this feature.
next prev parent reply other threads:[~2018-05-02 21:33 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-02 5:58 [RFC PATCH] Add /proc/<pid>/numa_vamaps for numa node information Prakash Sangappa
2018-05-02 21:33 ` Andrew Morton [this message]
2018-05-02 22:28 ` Dave Hansen
2018-05-02 23:17 ` prakash.sangappa
2018-05-03 8:46 ` Anshuman Khandual
2018-05-03 22:27 ` prakash.sangappa
2018-05-03 22:26 ` Dave Hansen
2018-05-07 23:22 ` prakash.sangappa
2018-05-08 0:05 ` Dave Hansen
2018-05-08 1:16 ` prakash.sangappa
2018-05-09 23:31 ` Dave Hansen
2018-09-12 20:42 ` prakash.sangappa
2018-09-12 20:57 ` prakash.sangappa
2018-09-14 1:33 ` Jann Horn
2018-09-14 6:21 ` Michal Hocko
2018-09-14 12:49 ` Jann Horn
2018-09-14 13:49 ` Michal Hocko
2018-09-14 18:07 ` Prakash Sangappa
2018-09-14 18:14 ` Jann Horn
2018-05-02 23:43 ` prakash.sangappa
2018-05-03 8:57 ` Michal Hocko
2018-05-03 22:37 ` prakash.sangappa
2018-05-04 11:10 ` Michal Hocko
2018-05-03 18:03 ` Christopher Lameter
2018-05-03 22:39 ` prakash.sangappa
2018-05-04 11:12 ` Michal Hocko
2018-05-04 16:18 ` Prakash Sangappa
2018-05-10 7:42 ` Michal Hocko
2018-05-10 16:00 ` Prakash Sangappa
2018-05-11 6:39 ` Michal Hocko
2018-05-04 14:57 ` Christopher Lameter
2018-05-04 16:27 ` Prakash Sangappa
2018-05-07 14:47 ` Christopher Lameter
2018-05-07 22:50 ` prakash.sangappa
2018-05-08 12:53 ` Christopher Lameter
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