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"? -- 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>