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Message-ID: <20171116091126.rqfvvdqngdbv3l4p@dhcp22.suse.cz>
Date: Thu, 16 Nov 2017 10:11:26 +0100
From: Michal Hocko <mhocko@...nel.org>
To: Roman Gushchin <guro@...com>
Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
Johannes Weiner <hannes@...xchg.org>,
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 15-11-17 23:14:09, 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: Michal Hocko <mhocko@...e.com>
Thanks!
> ---
> Documentation/vm/hugetlbpage.txt | 27 ++++++++++++++++++---------
> mm/hugetlb.c | 36 ++++++++++++++++++++++++------------
> 2 files changed, 42 insertions(+), 21 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.
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 4b3bbd2980bb..672377e6de9f 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -2973,20 +2973,32 @@ int hugetlb_overcommit_handler(struct ctl_table *table, int write,
>
> void hugetlb_report_meminfo(struct seq_file *m)
> {
> - struct hstate *h = &default_hstate;
> + struct hstate *h;
> + unsigned long total = 0;
> +
> if (!hugepages_supported())
> return;
> - 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,
> - h->free_huge_pages,
> - h->resv_huge_pages,
> - h->surplus_huge_pages,
> - 1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
> +
> + 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",
> + count,
> + h->free_huge_pages,
> + h->resv_huge_pages,
> + h->surplus_huge_pages,
> + (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)
> --
> 2.13.6
>
--
Michal Hocko
SUSE Labs
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