Re: [PATCH v5 1/2] mm: hugetlb: proc: add HugetlbPages field to /proc/PID/smaps

Naoya Horiguchi
2015-08-20T23:22:24Z

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On Thu, Aug 20, 2015 at 12:49:29PM +0200, Michal Hocko wrote:
> On Thu 20-08-15 08:26:26, Naoya Horiguchi wrote:
> > Currently /proc/PID/smaps provides no usage info for vma(VM_HUGETLB), which
> > is inconvenient when we want to know per-task or per-vma base hugetlb usage.
> > To solve this, this patch adds a new line for hugetlb usage like below:
> >
> > Size: 20480 kB
> > Rss: 0 kB
> > Pss: 0 kB
> > Shared_Clean: 0 kB
> > Shared_Dirty: 0 kB
> > Private_Clean: 0 kB
> > Private_Dirty: 0 kB
> > Referenced: 0 kB
> > Anonymous: 0 kB
> > AnonHugePages: 0 kB
> > HugetlbPages: 18432 kB
> > Swap: 0 kB
> > KernelPageSize: 2048 kB
> > MMUPageSize: 2048 kB
> > Locked: 0 kB
> > VmFlags: rd wr mr mw me de ht
>
> I have only now got to this thread. This is indeed very helpful. I would
> just suggest to update Documentation/filesystems/proc.txt to be explicit
> that Rss: doesn't count hugetlb pages for historical reasons.

I agree, I want the following diff to be folded to this patch.

>
> > Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> > Acked-by: Joern Engel <joern@logfs.org>
> > Acked-by: David Rientjes <rientjes@google.com>
>
> Acked-by: Michal Hocko <mhocko@suse.cz>

Thank you.
Naoya Horiguchi
---
From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Date: Fri, 21 Aug 2015 08:13:31 +0900
Subject: [PATCH] Documentation/filesystems/proc.txt: give additional comment
about hugetlb usage

---
Documentation/filesystems/proc.txt | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index f561fc46e41b..b775b6faaeda 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -446,7 +446,8 @@ indicates the amount of memory currently marked as referenced or accessed.
a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE
and a page is modified, the file page is replaced by a private anonymous copy.
"AnonHugePages" shows the ammount of memory backed by transparent hugepage.
-"HugetlbPages" shows the ammount of memory backed by hugetlbfs page.
+"HugetlbPages" shows the ammount of memory backed by hugetlbfs page (which is
+not counted in "Rss" or "Pss" field for historical reasons.)
"Swap" shows how much would-be-anonymous memory is also used, but out on swap.

"VmFlags" field deserves a separate description. This member represents the kernel
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