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

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Message-ID: <20160822074052.GC13596@dhcp22.suse.cz>
Date:   Mon, 22 Aug 2016 09:40:52 +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 09:07:45, Minchan Kim wrote:
[...]
> #!/bin/sh
> ./smap_test &
> pid=$!
> 
> for i in $(seq 25)
> do
>         awk '/^Rss/{rss+=$2} /^Pss/{pss+=$2} END {}' \
>          /proc/$pid/smaps
> done
> kill $pid
> 
> root@...x:/home/barrios/test/smap# time ./s.sh 
> pid:21973
> 
> real    0m17.812s
> user    0m12.612s
> sys     0m5.187s

retested on the bare metal (x86_64 - 2CPUs)
        Command being timed: "sh s.sh"
        User time (seconds): 0.00
        System time (seconds): 18.08
        Percent of CPU this job got: 98%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:18.29

multiple runs are quite consistent in those numbers. I am running with
$ awk --version
GNU Awk 4.1.3, API: 1.1 (GNU MPFR 3.1.4, GNU MP 6.1.0)

> > like a problem we are not able to address. And I would even argue that
> > we want to address it in a generic way as much as possible.
> 
> Sure. What solution do you think as generic way?

either optimize seq_printf or replace it with something faster.

-- 
Michal Hocko
SUSE Labs