Commit fcb2b0c5 authored by Roman Gushchin's avatar Roman Gushchin Committed by Linus Torvalds
Browse files

mm: show total hugetlb memory consumption in /proc/meminfo 

Currently we display some hugepage statistics (total, free, etc) in
/proc/meminfo, but only for default hugepage size (e.g.  2Mb).

If hugepages of different sizes are used (like 2Mb and 1Gb on x86-64),
/proc/meminfo output can be confusing, as non-default sized hugepages
are not reflected at all, and there are no signs that they are existing
and consuming system memory.

To solve this problem, let's display the total amount of memory,
consumed by hugetlb pages of all sized (both free and used).  Let's call
it "Hugetlb", and display size in kB to match generic /proc/meminfo
style.

For example, (1024 2Mb pages and 2 1Gb pages are pre-allocated):
  $ cat /proc/meminfo
  MemTotal:        8168984 kB
  MemFree:         3789276 kB
  <...>
  CmaFree:               0 kB
  HugePages_Total:    1024
  HugePages_Free:     1024
  HugePages_Rsvd:        0
  HugePages_Surp:        0
  Hugepagesize:       2048 kB
  Hugetlb:         4194304 kB
  DirectMap4k:       32632 kB
  DirectMap2M:     4161536 kB
  DirectMap1G:     6291456 kB

Also, this patch updates corresponding docs to reflect Hugetlb entry
meaning and difference between Hugetlb and HugePages_Total * Hugepagesize.

Link: http://lkml.kernel.org/r/20171115231409.12131-1-guro@fb.com


Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9852a721

Documentation/vm/hugetlbpage.txt

+18 −9
Original line number Diff line number Diff line
@@ -20,19 +20,20 @@ options. 


The /proc/meminfo file provides information about the total number of

persistent hugetlb pages in the kernel's huge page pool.  It also displays

information about the number of free, reserved and surplus huge pages and the

default huge page size.  The huge page size is needed for generating the

proper alignment and size of the arguments to system calls that map huge page

regions.

default huge page size and information about the number of free, reserved

and surplus huge pages in the pool of huge pages of default size.

The huge page size is needed for generating the proper alignment and

size of the arguments to system calls that map huge page regions.



The output of "cat /proc/meminfo" will include lines like:



.....

HugePages_Total: vvv

HugePages_Free:  www

HugePages_Rsvd:  xxx

HugePages_Surp:  yyy

Hugepagesize:    zzz kB

HugePages_Total: uuu

HugePages_Free:  vvv

HugePages_Rsvd:  www

HugePages_Surp:  xxx

Hugepagesize:    yyy kB

Hugetlb:         zzz kB



where:

HugePages_Total is the size of the pool of huge pages.
@@ -47,6 +48,14 @@ HugePages_Surp is short for "surplus," and is the number of huge pages in 
                the pool above the value in /proc/sys/vm/nr_hugepages. The

                maximum number of surplus huge pages is controlled by

                /proc/sys/vm/nr_overcommit_hugepages.

Hugepagesize    is the default hugepage size (in Kb).

Hugetlb         is the total amount of memory (in kB), consumed by huge

                pages of all sizes.

                If huge pages of different sizes are in use, this number

                will exceed HugePages_Total * Hugepagesize. To get more

                detailed information, please, refer to

                /sys/kernel/mm/hugepages (described below).





/proc/filesystems should also show a filesystem of type "hugetlbfs" configured

in the kernel.

mm/hugetlb.c

+24 −12
Original line number Diff line number Diff line
@@ -2975,20 +2975,32 @@ out: 


void hugetlb_report_meminfo(struct seq_file *m)

{

	struct hstate *h = &default_hstate;

	struct hstate *h;

	unsigned long total = 0;



	if (!hugepages_supported())

		return;



	for_each_hstate(h) {

		unsigned long count = h->nr_huge_pages;



		total += (PAGE_SIZE << huge_page_order(h)) * count;



		if (h == &default_hstate)

			seq_printf(m,

				   "HugePages_Total:   %5lu\n"

				   "HugePages_Free:    %5lu\n"

				   "HugePages_Rsvd:    %5lu\n"

				   "HugePages_Surp:    %5lu\n"

				   "Hugepagesize:   %8lu kB\n",

			h->nr_huge_pages,

				   count,

				   h->free_huge_pages,

				   h->resv_huge_pages,

				   h->surplus_huge_pages,

			1UL << (huge_page_order(h) + PAGE_SHIFT - 10));

				   (PAGE_SIZE << huge_page_order(h)) / 1024);

	}



	seq_printf(m, "Hugetlb:        %8lu kB\n", total / 1024);

}



int hugetlb_report_node_meminfo(int nid, char *buf)

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