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

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Message-ID: <20171116142152.GA21028@cmpxchg.org>
Date:   Thu, 16 Nov 2017 09:22:16 -0500
From:   Johannes Weiner <hannes@...xchg.org>
To:     Roman Gushchin <guro@...com>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Dave Hansen <dave.hansen@...el.com>,
        David Rientjes <rientjes@...gle.com>, kernel-team@...com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mm: show total hugetlb memory consumption in
 /proc/meminfo

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@...com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: Johannes Weiner <hannes@...xchg.org>
> Cc: Mike Kravetz <mike.kravetz@...cle.com>
> Cc: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
> Cc: Andrea Arcangeli <aarcange@...hat.com>
> Cc: Dave Hansen <dave.hansen@...el.com>
> Cc: David Rientjes <rientjes@...gle.com>
> Cc: kernel-team@...com
> Cc: linux-mm@...ck.org
> Cc: linux-kernel@...r.kernel.org

Acked-by: Johannes Weiner <hannes@...xchg.org>