Re: [PATCH v2] mm: show total hugetlb memory consumption in /proc/meminfo

From: Johannes Weiner
Date: Thu Nov 16 2017 - 09:22:49 EST


On Wed, Nov 15, 2017 at 11:14:09PM +0000, Roman Gushchin wrote:
> 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.
>
> Signed-off-by: Roman Gushchin <guro@xxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
> Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>
> Cc: kernel-team@xxxxxx
> Cc: linux-mm@xxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx

Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>