OOM conditions

[Tomeu Vizoso]

On Sat, Nov 7, 2009 at 12:06, Martin Dengler <martin at martindengler.com> wrote:
> On Fri, Nov 06, 2009 at 04:50:53PM +0000, Tomeu Vizoso wrote:
>> On Wed, Nov 4, 2009 at 14:16, Martin Dengler <martin at martindengler.com> wrote:
>> > On Fri, Oct 30, 2009 at 11:22:13PM +0100, Tomeu Vizoso wrote:
>> >> On Fri, Oct 30, 2009 at 16:58, Richard A. Smith <richard at laptop.org> wrote:
>> >> > Working the table at the Boston book festival I was reminded how
>> >> > painful the OOM stuff is on a gen 1. The demo machines were in
>> >> > this state a lot as each visitor would open up a new
>> >> > program.  Basically you have to just turn the unit off and restart
>> >> > as trying to recover is futile.
>> >>
>> >> What if activities had a higher oom_score? Would that protect enough
>> >> the processes that once killed require a system restart (X, shell,
>> >> etc)?
>> >
>> > See patch vs sugar-toolkit HEAD below[1] (I can backport to 0.82 if
>> > wanted).
>>
>> Maybe would be better to have the shell do that? So it works for
>> non-python activities.
>
> Patch inline below.

Looks great, thanks a lot. Have you seen less memory-induced lockups
on the XO-1?

Regards,

Tomeu

>> >> Regards,
>> >>
>> >> Tomeu
>> >
>> > Martin
>> >
>> Thanks,
>>
>> Tomeu
>
> Martin
>
>
> (untested) patch against
> http://cgit.sugarlabs.org/sugar-toolkit/mainline/tree/src/sugar/activity/activityfactory.py
> :
>
> From 4bd6fb9f7f245c2aed92d6964746627d0c96cbec Mon Sep 17 00:00:00 2001
> From: Martin Dengler <martin at martindengler.com>
> Date: Sat, 7 Nov 2009 10:55:16 +0000
> Subject: [PATCH] sacrifice activities to the OOM killer first
>
> change the OOM-killer score of launched activities to be the maximum.
> See discussion at http://linux-mm.org/OOM_Killer
> ---
>  src/sugar/activity/activityfactory.py |   35 +++++++++++++++++++++++++++++++++
>  1 files changed, 35 insertions(+), 0 deletions(-)
>
> diff --git a/src/sugar/activity/activityfactory.py b/src/sugar/activity/activityfactory.py
> index ee0fd92..5deee6e 100644
> --- a/src/sugar/activity/activityfactory.py
> +++ b/src/sugar/activity/activityfactory.py
> @@ -65,6 +65,39 @@ def _close_fds():
>             pass
>
>
> +def __oom_adj_pid(pid, omm_adj_value=None):
> +    """ Change a process' OOM likelihood to oom_adj_value.
> +
> +    By default, use the value of gconf path
> +    "/desktop/sugar/performance/oom_adj_default"; if none exists, make
> +    this process most likely to be killed (oom_adj_value=15).
> +
> +    Linux-specific.  See http://linux-mm.org/OOM_Killer for details.
> +    """
> +    oom_adj_fullpath = "/proc/%s/oom_adj" % pid
> +    if os.path.exists(oom_adj_fullpath):
> +        try:
> +
> +            # get values/defaults from gconf
> +            import gconf
> +            gconf_dir = "/desktop/sugar/performance"
> +            gconf_key = "oom_adj_default"
> +            client = gconf.client_get_default()
> +            if not client.dir_exists(gconf_dir):
> +                client.add_dir(gconf_dir, gconf.CLIENT_PRELOAD_NONE)
> +            if oom_adj_value is None:
> +                oom_adj_value = client.get_int(gconf_dir + "/" + gconf_key)
> +                if oom_adj_value is None:
> +                    oom_adj_value = 15
> +                    client.set_int(gconf_dir + "/" + gconf_key,
> +                                   oom_adj_value)
> +
> +            file(oom_adj_fullpath).write(oom_adj_value)
> +
> +        except:
> +            pass
> +
> +
>  def create_activity_id():
>     """Generate a new, unique ID for this activity"""
>     pservice = presenceservice.get_instance()
> @@ -276,6 +309,8 @@ class ActivityCreationHandler(gobject.GObject):
>             stdout=log_file.fileno(),
>             stderr=log_file.fileno())
>
> +        __oom_adj_pid(child.pid)
> +
>         gobject.child_watch_add(child.pid,
>                                 _child_watch_cb,
>                                 (environment_dir, log_file))
> --
> 1.6.2.5
>
>



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