Re: Memory overcommit

[Minchan Kim]

On Tue, Oct 27, 2009 at 3:36 PM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> On Tue, 27 Oct 2009 15:34:29 +0900
> Minchan Kim <minchan.kim@xxxxxxxxx> wrote:
>
>> On Tue, 27 Oct 2009 15:10:52 +0900
>> KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> wrote:
>>
>> > 2009/10/27 KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>:
>> > > On Mon, 26 Oct 2009 17:16:14 +0100
>> > > Vedran FuraÄ <vedran.furac@xxxxxxxxx> wrote:
>> > >> > Â- Could you show me /var/log/dmesg and /var/log/messages at OOM ?
>> > >>
>> > >> It was catastrophe. :) X crashed (or killed) with all the programs, but
>> > >> my little program was alive for 20 minutes (see timestamps). And for
>> > >> that time computer was completely unusable. Couldn't even get the
>> > >> console via ssh. Rally embarrassing for a modern OS to get destroyed by
>> > >> a 5 lines of C run as an ordinary user. Luckily screen was still alive,
>> > >> oomk usually kills it also. See for yourself:
>> > >>
>> > >> dmesg: http://pastebin.com/f3f83738a
>> > >> messages: http://pastebin.com/f2091110a
>> > >>
>> > >> (CCing to lklm again... I just want people to see the logs.)
>> > >>
>> > > Thank you for reporting and your patience. It seems something strange
>> > > that your KDE programs are killed. I agree.
>> > >
>> > > I attached a scirpt for checking oom_score of all exisiting process.
>> > > (oom_score is a value used for selecting "bad" processs.")
>> > > please run if you have time.
>> > >
>> > > This is a result of my own desktop(on virtual machine.)
>> > > In this environ (Total memory is 1.6GBytes), mmap(1G) program is running.
>> > >
>> > > %check_badness.pl | sort -n | tail
>> > > --
>> > > 89924 Â 3938 Â Âmixer_applet2
>> > > 90210 Â 3942 Â Âtomboy
>> > > 94753 Â 3936 Â Âclock-applet
>> > > 101994 Â3919 Â Âpulseaudio
>> > > 113525 Â4028 Â Âgnome-terminal
>> > > 127340 Â1 Â Â Â init
>> > > 128177 Â3871 Â Ânautilus
>> > > 151003 Â11515 Â bash
>> > > 256944 Â11653 Â mmap
>> > > 425561 Â3829 Â Âgnome-session
>> > > --
>> > > Sigh, gnome-session has twice value of mmap(1G).
>> > > Of course, gnome-session only uses 6M bytes of anon.
>> > > I wonder this is because gnome-session has many children..but need to
>> > > dig more. Does anyone has idea ?
>> > > (CCed kosaki)
>> >
>> > Following output address the issue.
>> > The fact is, modern desktop application linked pretty many library. it
>> > makes bloat VSS size and increase
>> > OOM score.
>> >
>> > Ideally, We shouldn't account evictable file-backed mappings for oom_score.
>> >
>> Hmm.
>> I wonder why we consider VM size for OOM kiling.
>> How about RSS size?
>>
>
> Maybe the current code assumes "Tons of swap have been generated, already" if
> oom-kill is invoked. Then, just using mm->anon_rss will not be correct.
>
> Hm, should we count # of swap entries reference from mm ?....

In Vedran case, he didn't use swap. So, Only considering vm is the problem.
I think it would be better to consider both RSS + # of swap entries as
Kosaki mentioned.


>
> Regards,
> -Kame
>
>
>



-- 
Kind regards,
Minchan Kim
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