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From: Andrew Morton <akpm@linux-foundation.org>
To: Jiang Liu <liuj97@gmail.com>
Cc: David Rientjes <rientjes@google.com>,
	sworddragon2@aol.com, Jiang Liu <jiang.liu@huawei.com>,
	bugzilla-daemon@bugzilla.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v2] mm: let /proc/meminfo report physical memory installed as "MemTotal"
Date: Wed, 20 Feb 2013 14:49:17 -0800	[thread overview]
Message-ID: <20130220144917.7d289ef0.akpm@linux-foundation.org> (raw)
In-Reply-To: <1361381245-14664-1-git-send-email-jiang.liu@huawei.com>

On Thu, 21 Feb 2013 01:27:25 +0800
Jiang Liu <liuj97@gmail.com> wrote:

> As reported by https://bugzilla.kernel.org/show_bug.cgi?id=53501,
> "MemTotal" from /proc/meminfo means memory pages managed by the buddy
> system (managed_pages), but "MemTotal" from /sys/.../node/nodex/meminfo
> means phsical pages present (present_pages) within the NUMA node.
> There's a difference between managed_pages and present_pages due to
> bootmem allocator and reserved pages.
> 
> So change /proc/meminfo to report physical memory installed as
> "MemTotal", which is
> MemTotal = sum(pgdat->present_pages)

Documentation/filesystems/proc.txt says

    MemTotal: Total usable ram (i.e. physical ram minus a few reserved
              bits and the kernel binary code)

And arguably, that is more useful than "total physical memory".

Presumably the per-node MemTotals are including kernel memory and
reserved memory.  Maybe they should be fixed instead (sounds hard).

Or maybe we just leave everything as-is and document it carefully.

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  reply	other threads:[~2013-02-20 22:49 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <bug-53501-27@https.bugzilla.kernel.org/>
2013-02-13  0:51 ` [Bug 53501] New: Duplicated MemTotal with different values Andrew Morton
2013-02-13  1:45   ` David Rientjes
2013-02-13  3:59     ` Andrew Morton
2013-02-14  3:19       ` David Rientjes
2013-02-14  4:01         ` Jiang Liu
2013-02-15  0:26           ` David Rientjes
2013-02-20  5:21             ` Simon Jeons
2013-02-20  7:09               ` David Rientjes
2013-03-02  2:21                 ` Simon Jeons
2013-03-04 11:18                   ` David Rientjes
2013-03-04 23:39                     ` Simon Jeons
2013-03-05 21:53                       ` David Rientjes
2013-02-16 16:27         ` [PATCH 1/2] vm: add 'MemManaged' field to /proc/meminfo and /sys/.../nodex/meminfo Jiang Liu
2013-02-19 21:29           ` David Rientjes
2013-02-20 17:27             ` [PATCH v2] mm: let /proc/meminfo report physical memory installed as "MemTotal" Jiang Liu
2013-02-20 22:49               ` Andrew Morton [this message]
2013-02-21 17:26                 ` Jiang Liu
2013-02-21 21:31                   ` Andrew Morton
2013-02-22 19:22                     ` Jiang Liu
2013-02-16 16:27         ` [PATCH 2/2] mm: protect si_meminfo() and si_meminfo_node() from memory hotplug operations Jiang Liu
2013-02-19 21:32           ` David Rientjes

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