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authorRoman Gushchin <guro@fb.com>2018-01-31 16:16:22 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-01-31 17:18:36 -0800
commitfcb2b0c577f145c7616843c9d4dcb4f9e5d88e29 (patch)
treee5e0adca3b30b9d2eac5cec139a9b588844766c8 /Documentation/vm
parent9852a7212324fd25f896932f4f4607ce47b0a22f (diff)
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: Roman Gushchin <guro@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: David 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/vm')
-rw-r--r--Documentation/vm/hugetlbpage.txt27
1 files changed, 18 insertions, 9 deletions
diff --git a/Documentation/vm/hugetlbpage.txt b/Documentation/vm/hugetlbpage.txt
index 59cbc803aad6..faf077d50d42 100644
--- a/Documentation/vm/hugetlbpage.txt
+++ b/Documentation/vm/hugetlbpage.txt
@@ -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.