OOM conditions

[Tomeu Vizoso]

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.

>> Maybe even have the background activities have a higher
>> oom_score than the one in the foreground?
>
> Interesting.  Another approach I'd love feedback on would be to set
> the allowed number of simultaneous running activities to be 2 (1 +
> Journal) and writing a simple control panel extension that would allow
> tweaking that, this oom_adj, and other related gconf values.

The downside I see to that is its complexity, maybe something simpler
would be enough?

Thanks,

Tomeu

>> Regards,
>>
>> Tomeu
>
> Martin
>
>
> 1. patch against
> http://cgit.sugarlabs.org/sugar-toolkit/mainline/tree/src/sugar/activity/main.py :
>
> diff --git a/src/sugar/activity/main.py b/src/sugar/activity/main.py
> index 93f34e6..c868e11 100644
> --- a/src/sugar/activity/main.py
> +++ b/src/sugar/activity/main.py
> @@ -31,7 +31,40 @@ from sugar.bundle.activitybundle import ActivityBundle
>  from sugar import logger
>
>
> +def __oom_adj_self(omm_adj_value=None):
> +    """ Change this 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/self/oom_adj"
> +    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_instance(constructor, handle):
> +    __oom_adj_self()
>     activity = constructor(handle)
>     activity.show()
>
>



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