From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id 69A026B0006 for ; Wed, 2 May 2018 17:33:27 -0400 (EDT) Received: by mail-pf0-f200.google.com with SMTP id c4so13820362pfg.22 for ; Wed, 02 May 2018 14:33:27 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id w12-v6si10012391pgs.183.2018.05.02.14.33.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 02 May 2018 14:33:26 -0700 (PDT) Date: Wed, 2 May 2018 14:33:23 -0700 From: Andrew Morton Subject: Re: [RFC PATCH] Add /proc//numa_vamaps for numa node information Message-Id: <20180502143323.1c723ccb509c3497050a2e0a@linux-foundation.org> In-Reply-To: <1525240686-13335-1-git-send-email-prakash.sangappa@oracle.com> References: <1525240686-13335-1-git-send-email-prakash.sangappa@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Prakash Sangappa 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 , Dave Hansen On Tue, 1 May 2018 22:58:06 -0700 Prakash Sangappa wrote: > For analysis purpose it is useful to have numa node information > corresponding mapped address ranges of the process. Currently > /proc//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//numa_maps was broken down by VA ranges showing the > exact numa node from where the pages have been allocated. > > The format of /proc//numa_maps file content is dependent on > /proc//maps file content as mentioned in the manpage. i.e one line > entry for every VMA corresponding to entries in /proc//maps file. > Therefore changing the output of /proc//numa_maps may not be possible. > > Hence, this patch proposes adding file /proc//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//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//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//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.