linux-kernel - Re: [PACTH v2 0/3] Implement /proc/<pid>/totmaps

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Date:   Mon, 22 Aug 2016 19:29:37 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Minchan Kim <minchan@...nel.org>
Cc:     Sonny Rao <sonnyrao@...omium.org>, Jann Horn <jann@...jh.net>,
        Robert Foss <robert.foss@...labora.com>, corbet@....net,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Konstantin Khlebnikov <koct9i@...il.com>,
        Hugh Dickins <hughd@...gle.com>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        John Stultz <john.stultz@...aro.org>,
        ross.zwisler@...ux.intel.com, jmarchan@...hat.com,
        Johannes Weiner <hannes@...xchg.org>,
        Kees Cook <keescook@...omium.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Cyrill Gorcunov <gorcunov@...nvz.org>,
        Robin Humble <plaguedbypenguins@...il.com>,
        David Rientjes <rientjes@...gle.com>,
        eric.engestrom@...tec.com, Janis Danisevskis <jdanis@...gle.com>,
        calvinowens@...com, Alexey Dobriyan <adobriyan@...il.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        ldufour@...ux.vnet.ibm.com, linux-doc@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Ben Zhang <benzh@...omium.org>,
        Bryan Freed <bfreed@...omium.org>,
        Filipe Brandenburger <filbranden@...omium.org>,
        Mateusz Guzik <mguzik@...hat.com>
Subject: Re: [PACTH v2 0/3] Implement /proc/<pid>/totmaps

On Mon 22-08-16 18:45:54, Michal Hocko wrote:
[...]
> I have no idea why those numbers are so different on my laptop
> yet. It surely looks suspicious. I will try to debug this further
> tomorrow.

Hmm, so I've tried to use my version of awk on other machine and vice
versa and it didn't make any difference. So this is independent on the
awk version it seems. So I've tried to strace /usr/bin/time and
wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, {ru_utime={0, 0}, ru_stime={0, 688438}, ...}) = 9128

so the kernel indeed reports 0 user time for some reason. Note I
was testing with 4.7 and right now with 4.8.0-rc3 kernel (no local
modifications). The other machine which reports non-0 utime is 3.12
SLES kernel. Maybe I am hitting some accounting bug. At first I was
suspecting CONFIG_NO_HZ_FULL because that is the main difference between
my and the other machine but then I've noticed that the tests I was
doing in kvm have this disabled too.. so it must be something else.

Weird...
-- 
Michal Hocko
SUSE Labs