Re: Can apps that disable dyntick be considered bugs?
 

Yes, this is heavier approach with other issues.
1. really everything is frozen so even some stuff that should be done is not done and system is mildly confused with amnesia after wakeup.
2. you need to wake up periodically each minute to ping the watchdog or system reboots. This means that your programs are periodically woken up too for short moments and can feel bad about it too (e.g. when playing sound or using network). SIGSTOP/SIGCONT may cause similar issues but at least it is not done every minute.

s2ram may indeed save more power but most people don't care if your tablet lasts 20 or 40 days in such standby mode. With clean firmware N810 lasts 30 days after fresh charge when not used at all. So it is not that bad when power management really works.

For better effect both ways can be combined (first send SIGSTOP to all suitable tasks and then do s2ram trick periodically).

Another solution for longer periods of inactivity is to implement suspend to disk (=card). Wakeup may take few seconds though. Still much better than current shutdown/boot procedure taking tenths of seconds.

Re: Can apps that disable dyntick be considered bugs?
 

30 days? I thought everyone recharged their NIT every day :)

The issue isn't only the time it requires the device to boot. The issue is also booting drains the battery life. An embedded device either doesn't boot much, or booting is quick. With the NIT's low battery life you get neither which drains the battery even more.

Say you fire up the NIT in the morning to check mail. Then you drive to work, suspend it, and after 8 hours you fire it up to check your mail again. Or you did this during your lunch break.

If you want a really high battery life while not using the device for long you'd suspend to disk. This is slower than suspend to RAM though, and on a computer it costs some time and energy to do this. You really don't want to suspend to disk every minute your laptop isn't in use, but I think for the NIT the difference is minor (especially with the SDHC kernel).

If you are using a lot of RAM suspend to RAM will use the swap to suspend to provided you have one (else it'll fail). In any case, only if you need to reboot suspend isn't an option. Else, it is almost always worth it after X minutes where X is e.g. 15, provided the suspending works correct. The ideal X is something one can researh after an implementation exists. This not only counts for laptops as well. It also counts for PCs.

Re: Can apps that disable dyntick be considered bugs?
 

All Linux palmtops I've used, indeed all palmtops, take a long while to boot (e.g. Zaurus, Psion Series 5, Newton).

Why suspend though? I can quite happily do this all week using the default dyntick+cpufreq+powering off components powersaving and still have battery life left.

As well as that, I can leave my N810 with wifi up and an ssh session running on my PC all evening (~4 hours, not doing much though, but that's like email), every night of the week and it will probably last a week.

Re: Can apps that disable dyntick be considered bugs?
 

Yes, I admit I got backup N810 which I currently don't use much. Ideal for various power management related tests. So far I managed to do only this one 'test' of keeping it unused in the drawer 3 or four times :-) Was around 30 days every time.
Not sure if you mean tablet and not sure if you mean suspend to disk or RAM (both are not part of current system) but anyway for tablet this is debatable. Tablet is more like a phone, not laptop with bad power management. It is meant to be always on always online so you can get your mail or receive Skype call anytime you wish. With no buggy application it works fine as is and lasts days while connected to wi-fi with light usage. Do you turn your phone off every X minutes where X is e.g. 15?

Re: Can apps that disable dyntick be considered bugs?
 

Suspending indeed goes against the 'always online' idea, even though my guess is large number of users don't actually use their tablets this way. Still If we assume that leaving it online is the way to go then something needs to be done about runaway processes.

How about a GUI to see which (userspace) applications have used lots of resources in a certain timeframe, and way to indicate which applications to halt (with SIGSTOP) when not using the tablet.

Re: Can apps that disable dyntick be considered bugs?
 

Well, I'm sorry, but I have a laptop at home and this device is always online when I have it at home (and soon with me, with 3G). If I wouldn't have a laptop I would use a desktop or workstation instead (actually, I do, but its almost always off, also to save costs on power which is becoming more expensive these days). I do like to wake up and see if I have e-mail based on the NIT's ambient light... but come on... its simply much easier to read e-mail on a bit bigger screen with my own favourite e-mail application with calendar support and so on.

When I leave the house I immediately don't have a connection anymore. No more WLAN. How am I always-on then? I'd need a seperate device for always-on. So, if you look at it this way, the NIT doesn't have the hardware to be always-on while on the move. If I travel, and I don't need to use the NIT, I should either close my resource hungry applications or use suspend. Heck, if I'd travel with my NIT, I wouldn't be able to use the on-board GPS because the chipset is crappy. The NIT doesn't have 3G either. It doesn't have as much storage as my Iriver H340 (with only 25 GB filled) which works several hours with Rockbox. So, IMO, or at least for me, the NIT isn't very useful as a always-on device.

Perhaps I should clearlify how I use my NIT: as a backup device in case I lost my way on the road, or if I'd need to look up something on the Internet while on the road. This doesn't happen much; so why leave the device on the whole time? I don't run many non-standard applications on the NIT either.

PowerTOP is a great application to see how many W an application uses but it requires a patched kernel.

Re: Can apps that disable dyntick be considered bugs?
 

Indeed. Ideally they'd be fixed, but I probably want a way of saying "the only non-system processes I want running when the screen is locked is Media Player, mplayer, MediaBox" (for example).

I'd envisage three lists:
* A whitelist of core system processes which should never be stopped.
* A whitelist of processes to keep running when locked/screen off
* A blacklist of processes to always stop when locking or the screen goes off after some timeout.

In fact, I remember suggesting SIGSTOP as part of Hildon Desktop and/or Maemo back in the OS2005 days :-)

There's a trickiness in measuring "lots of resources in a certain timeframe"; however some central database of processes/versions and whether they should be stopped, can be stopped or mustn't be stopped would solve a lot of those issues: the community can build it up over time.

Re: Can apps that disable dyntick be considered bugs?
 

This catch-all solution seems like a good idea considering the many ways apps can consume resources . I also like leaving it up to the user as some may actually want to let an app run even if it is resource hungry. Now we only need someoneone to er.. program it.