Messages in this thread | | | Subject | Re: [RFC PATCH] Add /proc/<pid>/numa_vamaps for numa node information | From | "prakash.sangappa" <> | Date | Wed, 2 May 2018 16:43:58 -0700 |
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On 05/02/2018 02:33 PM, Andrew Morton wrote: > 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?
This is mainly for debugging / performance analysis. Oracle Database team is looking to use this information.
>> 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.
Sure, I can update Documentation/filesystems/proc.txt file which is where 'numa_maps' is documented.
> > 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. > > Ok will take a look.
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