On Tue, 1 May 2018 22:58:06 -0700 Prakash Sangappa <prakash.sangappa@xxxxxxxxxx> 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. -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
