Re: Memory overcommit

["Vedran Furač" <vedran.furac@gmail.com>]

Hi and sorry for delay. Also, please CC me.

KAMEZAWA Hiroyuki wrote:

> On Tue, 13 Oct 2009 19:13:34 +0200
> Vedran FuraA? <vedranf@vedranf.mine.nu> wrote:
> 
>>> Against random-kill, you may have 2 choices.
>>>
>>> 1. use  /proc/<pid>/oom_adj 2. use  memory cgroup.
>>>
>>> Something more easy-to-use method may be appriciated. We have above 2
>>> now.
>> These are just bad workarounds for bad OOM algorithm. I tested this
>> little program on multiple systems (including windows) without any
>> tweaking and linux behavior is, unfortunately *the worst*.  :/
>>
> Yes, they are workaround. You can use /etc/sysctl.conf.
> But if making it default _now_, many threaded programs will not work.

Only Java ;) and only sometimes, at least from my experinence

> But I agree, OOM killer should be sophisticated.
> Please give us a sample program/test case which causes problem.
> linux-mm@kvack.org may be a better place. lkml has too much traffic.

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>

int main()
{
  char *buf;
  while(1) {
    buf = malloc (1024*1024*100);
    if ( buf == NULL ) {
      perror("malloc");
      getchar();
      exit(EXIT_FAILURE);
    }
    sleep(1);
    memset(buf, 1, 1024*1024*100);
  }
  return 0;
}


After running this on a typical desktop with gnome or kde, OOM killer
will kill 5-10 innocent processes before killing this one. Tested
multiple times on multiple installations.

Regards,

Vedran


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