OPP 5 and life drainage

[JePP]

Hey everyone, here are a few questions since I've become quite curious.

1) I'm keeping my Pandora (almost) constantly set at OPP 5. Does this effect life drainage much? What is the average life expectancy at this level?

2) Does the "OPP 5 life drainage effect" stay when the Pandora is on standby (lid closed)?

3) Does the effect differ with the set Mhz level? Or does it make no difference if I am at 600Mhz or 1000Mhz? (I know it affects my battery life, but I am asking for the overall Pandora health). Related question: If I want to use 600Mhz, should I always set it back to OPP 3? Or does the Pandora live long enough that it's not really worth the effort?

Thanks for the input!

 

[Linux-SWAT]

Thanks to Notaz's kernel work, OPP and MHz goes automatically down when the unit is not used.

 

[Binky]

This is worth looking at.

http://boards.openpandora.org/index.php/topic/10086-cpu-stress-test/

If you run for a day or two and get a reading of 800MHz at opp3 (an entirely possible result), then its probably safe to run at 775MHz - maybe a little more - without overclocking.

In my experience this is enough for most things.

If you want a more precise result, run the test for a week or so

I would, however be interested to understand the way all the magic power management works

 

[TrashyMG]

Also it being set to OPP5 is actually just setting the maximum allowable OPP level.. if you set the slider to OPP5 and are running at 600mhz, it's not running at the OPP5 level, It's running OPP3, once you overclock it will use a higher setting if needed.Unless I'm mistaken..

 

[Binky]

How does it work out 'if needed' ?

 

[Linux-SWAT]

Well, as he not only mind control ED's marketing decisions, Notaz uses his tele-control powers to order the users CPUs to work faster.

 

[Null]

How does it work out 'if needed' ?

http://www.kernel.org/doc/Documentation/cpu-freq/governors.txt

 

[Linux-SWAT]

I doubt governors are used in ARM/OMAP.

 

[Null]

I doubt governors are used in ARM/OMAP.

http://processors.wiki.ti.com/index.php/DVFS_User_Guide

http://www.eejournal.com/archives/articles/20120802-logicpd/?printView=true

http://groups.google.com/group/pandaboard/browse_thread/thread/6aa2cbe99c36919d.


Edit: cat /sys/devices/system/cpu/cpu0/


cpufreq/scaling_governor outputs performance on my Pandora, scaling_driver outputs omap.

 

[_wb_]

The governor is not used by default ("performance" just keeps it at max clockspeed all the time I think) because changing the clockspeed all the time has a bad effect on some emulators.

The main power saving comes from putting the cpu in deep sleep when it is idle - this effectively nearly completely powers it down. There are several idle states, called C1 to C5 (and C0 is normal operation mode). The deeper the sleep, the longer it takes to wake up; C5 is the deepest sleep. You can use System Info to check usage of the idle states - if you have nothing else running, you're mostly measuring the cpu usage of System Info itself. You can press "R" to reset those counters; the grey numbers between brackets are global statistics since your last boot. You'll notice that a lot of time is spent in C5.

I think that any time spent in C5 is effectively as if your cpu is not on, not just in terms of battery use but also in terms of wear and tear.

 

[klapse]

I think that any time spent in C5 is effectively as if your cpu is not on, not just in terms of battery use but also in terms of wear and tear.

This is how I understand Pandora Powersaving as well. When it wakes up to do work, it does it at fullspeed, then goes back to sleep.

 

[JePP]

Sorry to bring this up a little late, but are these two assumptions right?

1) I have set to OPP5 and 600Mhz. It says OPP5, but in reality it is at OPP3 as long as I'm not overclocking enough for OPP5 to be needed?

2) I do NOT need to set OPP5 down to OPP3 manually in order to preserve a good lifespan of the Pandora? My Pandy will not become unusuable due to this after a couple of years?

Thanks!

 

[Binky]

I think so, but wait for someone else to reply before taking my word for it

 

[TrashyMG]

Correct, If you want to see what OPP level you're currently running at.. try this nice utility

 

[JePP]

Correct, If you want to see what OPP level you're currently running at.. try this nice utility

Well, even at 600Mhz it constantly show's me OPP5 - so are you sure it's getting the right OPP level displayed? Or might the Pandora still be at OPP5 even at 600Mhz?

 

[TrashyMG]

Yeah it's only showing what it's set to not what it actually is. My mistake I thought it was getting that live.. 

So I did a test on my 1Ghz unit..

When I set the CPU speed to 1Ghz and run dmesg in the command line it outputs:
max OPP set to 4

I then switch it to 600mhz and run dmesg again:
max OPP set to 2

Switched it to 750mhz:

max OPP set to 3

so it is switching the OPP level down automatically, I have the max OPP slider set to 5 the whole time (I know the 1Ghz unit only has 4 OPP levels).

 

[ZXDunny]

I have been running at OPP5 for about two years, maybe a little more, on my CC256 Pandora at 950MHz. It's still working, and doesn't rattle when I shake it so it's not falling to bits.

D.

 

[_wb_]

Oh, I didn't realize that the OPP is automatically switched down when you change the cpu speed. Is there a place in /proc or /sys where you can find the actual OPP value, not the max?

Also, as far as I understand, the CPU lifetime depends mostly on the time it is being used, not the time when it is sleeping. Unless you're doing stuff like CPU stress tests all the time, your CPU is sleeping a lot.

I doubt there will be any Pandora at all where the SoC is the first thing to break, even if you push it to its limits. I wouldn't worry about it.

 

[fusion_power]

Hm, I thought that Pandora System Info shows the current OPP Level, that's why I was worried because it always showed OPP5, even at 600MHz (CC classic Pandora). I manualy limited OPP to 3 so it looked much saver to me. ^^

Not much done with overclocking yet but I guess 800MHz could be possible, even with OPP3.

 

[TrashyMG]

Oh, I didn't realize that the OPP is automatically switched down when you change the cpu speed. Is there a place in /proc or /sys where you can find the actual OPP value, not the max?

Also, as far as I understand, the CPU lifetime depends mostly on the time it is being used, not the time when it is sleeping. Unless you're doing stuff like CPU stress tests all the time, your CPU is sleeping a lot.

I doubt there will be any Pandora at all where the SoC is the first thing to break, even if you push it to its limits. I wouldn't worry about it.

Outside of the dmesg log, I have yet to find were you can see the current OPP level setting. I've crawled through the proc and sys directories for about an hour.