On Mon, Jan 05, 2015 at 01:35:00PM -0800, Andrew Morton wrote: > On Mon, 5 Jan 2015 12:44:31 -0500 Rafael Aquini <aquini@xxxxxxxxxx> wrote: > > > This patch introduces 'kernelpagesize_kB' line element to /proc/<pid>/numa_maps > > report file in order to help identifying the size of pages that are backing > > memory areas mapped by a given task. This is specially useful to > > help differentiating between HUGE and GIGANTIC page backed VMAs. > > > > This patch is based on Dave Hansen's proposal and reviewer's follow-ups > > taken from the following dicussion threads: > > * https://lkml.org/lkml/2011/9/21/454 > > Dave's changelog contains useful information which this one lacked. I > stole some of it. > > : 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. > : > : This patch introduces 'kernelpagesize_kB' line element to > : /proc/<pid>/numa_maps report file in order to help identifying the size of > : pages that are backing memory areas mapped by a given task. This is > : specially useful to help differentiating between HUGE and GIGANTIC page > : backed VMAs. > : > : This patch is based on Dave Hansen's proposal and reviewer's follow-ups > : taken from the following dicussion threads: > : * https://lkml.org/lkml/2011/9/21/454 > : * https://lkml.org/lkml/2014/12/20/66 > > > > + seq_printf(m, " kernelpagesize_kB=%lu", vma_kernel_pagesize(vma) >> 10); > > This changes the format of the numa_maps file and can potentially break > existing parsers. Please discuss. > > I'd complain about the patch's failure to update the documentation, > except numa_maps appears to be undocumented. Sigh. What the heck is "N0"? > That's a nice opportunity to attempt to sharp my doc writing skills. Sorry for the total failure to identify it earlier. I just took it as a TODO note to send a patch to document this interface soon. Happy new year. -- Rafael -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>