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Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

Well check the wiki here on TMO. There are people against OC and in favor of it. Currently I'm on KP49 and on DSP profile if I dont forget to turn it on :) generally the stock settings are good for me. The profiles like ULV, XLV... are supposed to save battery and give performance but it is said that the calculations in it are wrong/not perfect and should be tweaked for each device. Sometimes in daily use I think that OC is overated. For answering cals and sending sms 600mhz on standard stock settings is OK.

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

meh id rather stick with stock kernel and stock oc, my phone kept dicking up with power kernel, not saying it isnt good, just phone went to wank. but stock runs fast

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

ULV, XLV, etc have nothing to do with overclocking, except that the kernel that allows you to overclock if you want to (I do) also allows you to use these settings if you want to (I do).

The reason that different N900s have different best settings has nothing to do with whether the calculations are wrong/not perfect as you said, but because N900s are not identical and the only way you can find out what is best for your N900 is by testing it.

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

Those profiles have lower voltages than stock, their only differece is that each has a lower voltage (for each frequency than the previous one).
Lower voltages mean less power consumed by the cpu (you know that P = V*I, don't you?), and so, lower cpu temperature which reduces the risk of damage and aging of the cpu, and a expected longer battery life.
They are also deprecated for kernel power 49 and variants. The reason is that the cpu has a feature called SmartReflex (google it) which should adjust the voltages dinamically to the minimum possible to get the best power savings. Unfortunately, Nokia didn't implement correctly the driver for SR and it caused inestability and random reboots, so Nokia finally disabled SR leaving our devices with less than optimal voltage profiles, but stable.
Our dear TMO member Freemangordon realized that and took the work of reading TI's documents, did the right calculations and put them in the SR driver for kp49, correcting also the overclocking frequencies in the process.
So with kp49 and variants, the set of OC frequencies is different, and SR no longer causes inestability (on most devices at least, although there are a few reports of inestability and probably kp50 will have revised calculations), so it is better to enable SR and let the device calculate it best voltages. There is also a new overclocking profile "dsp" by Freemangordon, which has SR enabled, the new corrected frequencies and the optimum dsp overclocking for the new feature of recording at 720p, also kindly brought to us from the N9 by Freemangordon.

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

http://tonism.2bit.ee/N900/starving.png

...and here.

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

1. I don't know why the ideal's min. freq. as 500 is saving power... Why isn't it 250? Could you explain?
2. Should I manually enable SmartReflex in e.g. QCpuFreq to make it work?

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

Also note undervolting too much can cause crashes, system instability and corrupt data. Bear this in mind if using XLV ULV and Starving especially at lower frequencies.
SR seems to work nice for me at the moment on KP.

The idea behind the 500Mhz in ideal AFAIK...
..is the process is done quicker and the system hits idle quicker.
Saving battery in the process. I would think it depends on your usage, tho.

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

Exactly, if I am listening to hours of MP3s is it better for the n900 to sit at 250MHz or 500MHz?

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

is there any chances of damaging my cpu or board with underclocking ?

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

This is why I started using SR.
I use the media player for playing music a lot on a day to day basis.
I found that the media player makes the processor sit at 125Mhz Stock.
On Ideal 500Mhz my battery didn't last as long as stock. I even changed removed the avoid freqs to 250Mhz then 125Mhz, not much difference.
If SR is stable on your device (should be on KP), I find it saves a good bit of battery for my usage.

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

Did you keep 250Mhz disabled?

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

Back in the day, several tests were done to find the "peek" for where the CPU works most efficiently. Most systems can run faster or slower, but that peek is where it runs best (cycles / amp-hour). Titan did most of the testing, and found that the sweet spot was between 500 and 600, depending on the device.

There's also the "race to finish" idea, that the faster you get something done, the more time the CPU can sit in idle mode before it has to do anything else. Suppose a background process running at 250Mhz takes 2 seconds to complete (like checking crcs on files). If that same computation can be done in 1 second with a default of 500Mhz, the energy saved in the 1 second of extra idle time outweighs the extra voltage used to get to 500Mhz. (Especially when the CPU is operating more efficiently at 500Mhz than it is at 125Mhz.)

The only time this doesn't work is when you have a *constant* stream of work at a slower rate (like decoding mp3 streams and dealing with filling audio buffers by hand, a-la gstreamer). Then reguardless, you're going to run above 0, making the task eat a bit more.

FYI: The default Nokia kernel disabled 125Mhz mode, leaving idle mode at 250Mhz. 125 was removed because it was found to be unstable, causing more than it's fair share of problems (mainly write corruption to flash and dsp issues). I would personally avoid that frequency set. In fact, I run 500-900, and find my battery lasts 2 days with moderate usage if needed. (I generally charge every night, regardless of level.)

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

No! Didn't think of that. I could try it for a bit. Thanks for the suggestion.

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

Tried that today and it was flat by 14:30, normally get a day and a bit.

Will test it for a bit longer.

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

Now I'm testing stability of kp49+ideal+sr, limits 500-720 on normal daily usage (crashes etc.) I'll let you know as soon as I finish it - it should be on 19th Jan

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

Unfortunately, SmartReflex is very unstable with kp49+ideal, limits 500-720. During 12 hours I had a reboot (or two, because my setting were set to default kernel)
I strongly discourage from using SR with that profile.

Now I'll test XLV profile, kp49, limits 250-600 with SR

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

I shall say this only once.

Smart reflex in kernel-power v49 renders setting voltage profiles OBSOLETE.

If you are going to use smart reflex then DO NOT BOTHER changing the voltage profiles. Smart reflex automatically undervolts your CPU for you to a level appropriate for your CPU better than any of your empirical testing can indicate.

The only other thing you can really futz with is scaling governor and clock speeds (which is a whole other 1000 post thread as to what is good/bad).

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

And is it possible to get the stock voltages once having set for instance xlv as default?

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

LOL I dunno.

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

And in addition to what vi_ says - enabling SR on undervolting profiles may lead to instability as initial voltage could be too low and SR could not compensate fast enough.

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

Yeah. And because of that I'd like to switch between stock profile with SR and undervolting profile
Is some config generated automatically? Does kernel-power-settings save the old profile when switching to a new?
I've found in ~/.kernel/600 some old profile, but incompatible with kp49 (old freqs)

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

What about: kernel-config load stock, thought that would load nokia's settings?

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

file not found stock

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

@marmistrz
Unless you changed the default profile, like you mentioned.
I saved a file called "stock" before I saved anything, so...
...works for me, AFAIK it isn't a profile in KP.

As for extending my battery life gone back to 125Mhz-600Mhz SR.
it seems to work the best. Especially when using media player all day.

Re: Difference beetween Nokia, LV, ULV, XLV, Ideal
 

Can you not replace the values in the default profile?

sudo gainroot
cd usr/share/kernel-power-settings/
vi default

and replace FREQS with the default below

then save this profile as "stock".