[Sugar-devel] Killing activities when memory gets short

Gary Martin garycmartin at googlemail.com
Wed Aug 11 12:23:20 EDT 2010

Hi James,

On 11 Aug 2010, at 04:05, James Cameron wrote:

> On Tue, Aug 10, 2010 at 05:48:00PM -0700, John Gilmore wrote:
>> ... and was also unsuccessful in convincing OLPC to prelink the shared
>> libraries before shipping a release, thus allowing read-only pages to
>> not get dirtied with shared library linkage relocations.
> 10.1.2 release candidate os851 has prelink before shipping, it's done in
> the builder.

Out of curiosity, just been testing two XO-1s side by side one os850 and one os851. Rough observations (repeated about 12 times):

- resuming/starting a sequence of activities after another reliably gets to 9 simultaneous activities (Terminal, Calculate, Log, Pippy, Implode, Chat, Moon, Paint, Memorize)

- the tenth activity I happened to be testing, Turtle Blocks, usually triggered an OOM hang of some kind

- the OOM hang was usually Turtle Blocks failing to launch. Failed launch would consist of the pulsing startup window, then hanging at a mainly dark grey screen with some partial toolbar light grey fill, non-responsive UI for ~30 seconds to a number of minutes (possibly 5 or 10min), finally you'd be dropped back at the last activity you had successfully launched (Memorize in my test cases).

- on three occasions os851 successfully started Turtle Blocks

- on one occasion os850 successfully started Turtle Blocks, however on one occasion resuming Turtle Blocks os850 managed to trigger an OOM kill of the Sugar shell resulting in all resumed activities dying and being dropped back at the home fav ring view.

- as Turtle Blocks seems a little more memory intensive than some other activities, I tried a few others as the tenth and onward test case. Write as no. ten usually was fine and Distance as eleven. Then trying Maze, or Speak as no. twelve would trigger OOM and the activity would be killed (after some delay, as noted above).

- on one occasion trying to start Maze in os850 as activity no. twelve, managed to trigger an OOM kill of the Sugar shell.

So, not significant results over just 12 cycles for each XO-1 (need finer grained testing rather than 'number of activities'). Both exhibited long UI lockup's when launching an activity while resources were already maxed out, usually resulting with the activity in question being killed; but os850 did trigger OOM to kill the Sugar shell twice, bringing down all activities with it, where as os851 didn't.


P.S. of corse you'll now tell me os850 was also pre-linked (I couldn't see anything about it in the build notes for either os850 or os851), and I'll look silly for trying to test for a difference, confirming my results were non significant ;-)

> -- 
> James Cameron
> http://quozl.linux.org.au/
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