[Palm OS] Apps on cards and batteries
 

Hello,

Thanks to tips I was able to run programs from cards (N800). But as I am running some programs non-stop (Agendus) I noticed quick battery drain.

May it be caused by continuous communication between gvm and card (even when locked) or cause lies somewhere else?

My second suspect is cheap 16GB SDHC card in internal slot. I recently switched slots for 4GB Kingston and this no-name. While in external slot 16GB caused no problems.

TIA

Re: [Palm OS] Apps on cards and batteries
 

I think you've put your finger on a potential problem with running applications from the card. To access the card, the N800 (or N810) must power on the card, so frequent accesses will drain the battery faster. The kernel turns off power to the card when not in use, it's part of the power saving strategy of the omap platform. It can turn off various part off- and on-chip when not in use, and it can fiddle with the voltage levels too.

But it all depends on how often the card needs to be accessed. When cloning the operating system to a card we know what happens: An application is initially read from the card, page-by-page as needed, and after a while it'll all be in RAM (the part that is used, anyway) and there's no need to access the card merely because the program is active. But we don't know how GVM is handling the card when we launch a PalmOS application from a card. Someone could possibly trace this with 'strace', for example.

Then there's the question of storing data on the card. Do you have Agendus data on the card? Is it accessing it often?

Re: [Palm OS] Apps on cards and batteries
 

It depends.

If the application itself IS on the card, it creates a temporal copy on the storage heap (aka gvm.store which should always be in internal memory). So, no card accesses here.

PalmOS should only read the card if the application is actively reading/writing to files from it. And shouldn't Linux cache those reads/writes? (Unless GVM is opening them in some wierd way).

Re: [Palm OS] Apps on cards and batteries
 

Ah, you're right of course - and for m68k apps (the vast majority) it's a necessity because of the need to translate the application via PACE (m68k->arm jit). (If you look with FileZ you'll see all those a68 files, which are generated on the fiy when you execute something.)

And yes, Linux should cache reads/writes, but it does depend a bit on exactly what GVM is doing.

I didn't mention the original poster's "second suspect", the SD card. It's not unheard of that some cards use a lot more juice than others, but it would be a bit strange if it made a difference being in the internal vs. the external slot.

Re: [Palm OS] Apps on cards and batteries
 

There are small differences between the N800's internal and external slots, and apparently, cards will use slightly less power in the external slot than in the internal. See the "Update" section of an old blog post by Philip Langdale.

Re: [Palm OS] Apps on cards and batteries
 

Thanks for replies.

Reversed cards again (4gb internal, 16gb external) and while usage is still bigger than normally it is better than previously.

Unfortunately Agendus uses standard PalmOS bases so here drain shouldn't be so big. 'Unfortunately' because with terminal crash whole really useful data will go to hell, in this case card trick is only for quick app restoration :/, OTOH this version of GVM is in my opinion, much, much more stable and it became useful at last.