[maemo-developers] Why should I write apps for Maemo?

[From: Eero Tamminen]

Hi,

ext Dawid Lorenz wrote:
> On 10 May 2010 14:09, Eero Tamminen <eero.tamminen at nokia.com<mailto:eero.tamminen at nokia.com>> wrote:
> Actually, what I'd love to be able to do is simply flush swap space
> periodically. I've noticed that once swap space usage passes approx.
> 20%, device gradually becomes unbearable with regular day-to-day usage,
> hence reboot is essential.

I think the problem you're getting that almost all of that 20% is
fairly actively used.

Rest of the swap is mainly useful for the cases when there's just a very
temporary large memory need, or for applications that leak large amounts
of memory they'll never again touch.


> Manually restarting
> /etc/init.d/tablet-browser-daemon doesn't help much, yet it seems that
> browsing web is quite sluggish regardless of restarting browserd. I'd
> simply like to know the way to release swap space somehow, instead of
> rebooting device.

Something that could help slightly is disabling pre-starting for
applications that you don't use. Comment out the pre-starting lines
where  appropriate:
   grep Prestarted /usr/share/applications/hildon/*.desktop


 > Perhaps restarting some other services?

sp-endurance is created for catching things that leak resources:
http://wiki.maemo.org/Documentation/devtools/maemo5/sp-endurance
http://wiki.maemo.org/Documentation/devtools/maemo5/sp-endurance-postproc

Probably the best way to use it in your case is to write a small script
that takes a snapshot to some directory under MyDocs every night
(untested):
------ snapshot.sh -------
#!/bin/sh
# take endurance snapshot once a day
while true; do
	save-incremental-endurance-stats /home/user/MyDocs/endurance
	sleep $((24*60*60))
done
--------------------------

Then run it as root, so that it gets started first time some
time at night (let's assume night is in 6 hours):
	# sleep $((6*60*60)); ./snapshot.sh

The reason to take the snapshots at night is that usually the device
is then in consistent state, apps aren't actively used etc.  Best would
be if you could always leave the device to same state for the night.


After device starts to be slow (you said 5-6 days?), post-process
the data:
	parse-endurance-measurements /home/user/MyDocs/endurance/1*

And see what processes it reports to be growing in memory usage.

If the process specific bar charts show something going to swap
and coming back from there, it means that this amount of memory is
actively used, not just dormant.


> The other option is tell specific "core" (like phone app) applications
> to be never swapped away, yet I don't know whether that's possible at all.

This is already done to a reasonable level with memory locking and
the policy daemon.


	- Eero