Develop Bugs

[Q] what exactly is undervolting

i have used the search and not found any solid info
what are the benefits of it if any

I haven't heard of people undervolting their fone, although i haven't looked to much.
This would mean though reducing the power that the CPU gets. I would imagine this increases battery life among other things.

Your right about what it is, but almost every custom rom/ kernel is undervolted in development section.
Sent from my HTC Desire using XDA App

Undervolting means, the CPU (or hardware in the phone) gets lower voltages, thus saving more battery & not loosing performance.
Undervolting is a process which reduces the excess "voltage" given to the CPU using a software. This is widely used as a cooling solution and in my opinion more effective than any other cooling solution available (thermal paste, cooling pad, etc) at NO cost. Undervolting will NOT compromise performance at all. Underclocking and Overclocking (clock speeds) is whats responsible in regards to performance. Benchmarks will also prove that performance remains the same.
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Not excess voltage but fully, manufacturer guaranteed, stable Core voltage to lower guesswork voltages which may or may not work and may or may not cause data loss/corruption.
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- Sent via HTC Desire -

A cpu needs power for every 'clock cycle'. 1Ghz means there are a billion per second. IF you lower the voltage, there is less power used. But if you lower it too much, the cpu wo'nt be able to 'cycle its clock'...
So undervolting doesn't affect performance, since the cpu remains on 1Ghz. It decreases the power used, so you get better battery life.
Every single cpu is different, so HTC has chosen a default voltage that (shoud) work on all phones they sell. But your particular cpu could be able to work at a lower voltage. It's just a matter of trail and error. Decrease the voltage until the cpu stops working, then higher it a bit. That way you've undervolted your cpu so it uses the least power.

koenvbeek said:
A cpu needs power for every 'clock cycle'. 1Ghz means there are a billion per second. IF you lower the voltage, there is less power used. But if you lower it too much, the cpu wo'nt be able to 'cycle its clock'...
So undervolting doesn't affect performance, since the cpu remains on 1Ghz. It decreases the power used, so you get better battery life.
Every single cpu is different, so HTC has chosen a default voltage that (shoud) work on all phones they sell. But your particular cpu could be able to work at a lower voltage. It's just a matter of trail and error. Decrease the voltage until the cpu stops working, then higher it a bit. That way you've undervolted your cpu so it uses the least power.
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Very sensible answer..Thanks

koenvbeek said:
A cpu needs power for every 'clock cycle'. 1Ghz means there are a billion per second. IF you lower the voltage, there is less power used. But if you lower it too much, the cpu wo'nt be able to 'cycle its clock'...
So undervolting doesn't affect performance, since the cpu remains on 1Ghz. It decreases the power used, so you get better battery life.
Every single cpu is different, so HTC has chosen a default voltage that (shoud) work on all phones they sell. But your particular cpu could be able to work at a lower voltage. It's just a matter of trail and error. Decrease the voltage until the cpu stops working, then higher it a bit. That way you've undervolted your cpu so it uses the least power.
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How would one go about under volting .i have tried everything suggested to me and nothing really seems to make a difference
Sent from my HTC Desire using XDA App

Most kernels are undervolted and unless you can compile the kernel for yourself you are stuck with the values given by the creator. There are two exceptions for this, HAVS kernels which automaticly chose a voltage depending on temperature and some other stuff and SVS kernels with snq-'s volt selection interface (found in Leedroid and maybe some other kernels/roms).
So what exactly have you tried and what did you expect to see? Because the difference won't be that noticeable.

TheGhost1233 said:
Most kernels are undervolted and unless you can compile the kernel for yourself you are stuck with the values given by the creator. There are two exceptions for this, HAVS kernels which automaticly chose a voltage depending on temperature and some other stuff and SVS kernels with snq-'s volt selection interface (found in Leedroid and maybe some other kernels/roms).
So what exactly have you tried and what did you expect to see? Because the difference won't be that noticeable.
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I have tried battery calibration, using app watch dog to let me know which apps are using excessive CPU. Putting my brightness down to 10%, making sure not everything is synced, the only thing synced is beautiful widgets every 4 hours. And just about everything else that has been put forward to me. Here's another example I just taken my phone off charge at 100% and wrote this and I'm now at 73 %. And its only taken2 mins to write
Sent from my HTC Desire using XDA App

adz63 said:
I have tried battery calibration, using app watch dog to let me know which apps are using excessive CPU. Putting my brightness down to 10%, making sure not everything is synced, the only thing synced is beautiful widgets every 4 hours. And just about everything else that has been put forward to me. Here's another example I just taken my phone off charge at 100% and wrote this and I'm now at 73 %.
Sent from my HTC Desire using XDA App
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So in short you havent tried any kernel with undervolting at all!

Well that all has nothing to do with undervolting, but (extra) undervolting will not fix the drain problem you have.
Do you use setCPU cause your sig says you run at 1113MHz, which cause higher consumption. Also did you set your wifi sleep policy to never(setting-wireless and network-wifi settings-press menu-advanced-wifi sleep police).

At the moment I have the havs kernel that comes with oxygen 2.0 rc6. I have posted another topic about is the kendal good for battery life etc and no1 has told that another kendal would make anything better
Sent from my HTC Desire using XDA App

TheGhost1233 said:
Well that all has nothing to do with undervolting, but (extra) undervolting will not fix the drain problem you have.
Do you use setCPU cause your sig says you run at 1113MHz, which cause higher consumption. Also did you set your wifi sleep policy to never(setting-wireless and network-wifi settings-press menu-advanced-wifi sleep police).
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@TheGhost1233, how exactly does one decide which kernel suits us best..
Eg: I see two undervolted kernels (I think) at 875 and 925 mV. I have no idea how to decide. Trial and error?
Froyo Kernel [email protected] min
Froyo Kernel [email protected] min

@droidzone Yes trial and error. The mentioned voltage is the lowest the cpu will get at 245MHz. Not all devices are stable with 875mV (you will know if your phone freezes up) so then you move up to the 925mV min. Other than the voltage there is no difference between 875mV or 925mV.
With the HAVS kernels it can take a while before you notice the freezes cause the voltage is dynamic, so be careful if you need your phone as a alarm clock.

question about voltage/minimum clock frequency

hi there.
I've been tinkering with voltages and cpu frequencies lately.
I noticed that, with stock voltage values, i have "900" for 122, 245 and 368 mhz.
Now the question is, leaving governors aside for a moment: if i set cpu minimum to 122 or 368, there shouldn't be any battery drain differencies, since they both have the same voltage value.
But technically if i have some background stuff going on, with screen off or when the phone is idle, they will be processed faster with 368 mhz, while with 122 they will take longer to carry on or even force the phone to work to get to a higher frequency to finish the task.
Now i maybe saying a lot of bullcrap since i'm not a developer nor a hardware guy,
but if what i said is true, then in theory it would not be the same if i put minimum to 368, it would actually be better for performance AND the battery??

No, as I have learned from another user here; even if the voltage is the same, the power draw is still different. 122mhz will still use the least amount of power

[Q] Same voltage = Same battery drain?

Hello!
I recently noticed how frequencies 122MHz through 460MHz all employ the same voltage (900mV). I've come to understand that the higher the CPU frequency the faster your battery will drain. What I don't understand is why a higher frequency will drain your battery faster.
Is the only cause for higher battery drain when running a higher frequency, the higher voltage which comes with a higher frequency, or are there other factors?
If, then, a higher voltage is the only cause, then my battery would not drain faster if I clocked my minimum frequency at 460MHz instead of 122Mhz?
Thanks in advance to anyone who can shed some light on this!

Hi
cpu power consumption at a specific frequency is bound to its voltage.
you should test a voltage for a frequency while your device has 100% workload, because you could find a voltage so that your device is stable while being idle, but freezes when it needs to work. (for more information search for linux phc)
my conclusion:
the voltage for a specific frequency has minimum!
you can set your minimum frequency to 460 if you want to, since the screen consumes most power, it should not matter that much. i have set my minimum freq that high, too. I believe that way, my phone needn't raise the frequency when dooing simple stuff, like playing music.... but i am just guessing.
i theory it must get hotter than at lower frequencys, but i did not notice that.
i have had a palm pre and a custom kernel introduced a voltage on demand governor, which kept the device at 1ghz all the time, but changes the voltage with the workload. i think the developer of the awesome idea is "unixpsycho" ... i would like to see something similar on android.
greetings
matto
EDIT:
http://en.wikipedia.org/wiki/Dynamic_frequency_scaling
it looks like it is bound to the frequency, too!
~const*f*V^2
the Voltage is quadratic, that means it tkes a higher priorety.
e.g. lowering the voltage from 900mv to 800mv => (0.8^2)/(0.9^2) ~ 0.79
460mhz*0.79~363mhz
=> [email protected] consumes as much power as [email protected] (Stock)

Setcpu Profiles

Hey guys, I'm just wondering what settings do you have on your setcpu for the best performance and battery life? I'm totally new to this lol
Sanks

kazemagic said:
Hey guys, I'm just wondering what settings do you have on your setcpu for the best performance and battery life? I'm totally new to this lol
Sanks
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i i think that ondemand is the best for daily using... i'm using cm10 rom and i have some music problem so i'm using interactive and it's ok. if you don't use games or heavy apps, you can underclock it to 1ghz or even less and put on powersave.. but you have to try and find the best for you

My setup is a little complicated. I use the ondemand governor, then for the profiles I make it use powersave and under 760mhz between 1am and 8:30am which seems to really help during the night. Also set it to use 760mhz max when the screen is off.
When charging or above 40% battery I allow it to run full speed, but only when the screen is on, therefore helping charge times. On charge or above 80% I set the governor to performance.
In call I set the clock to max 1000mhz and conservative to try and allow calls on low-battery to work properly without lag but also without killing the battery.
I have a couple of other options set for very low battery ( < 12% ) too, but those are only to extend the battery if it's dying.
I wouldn't say all this is necessary... but I need my phone to keep working at all times as I use it for receiving business calls.
It's just a matter of playing around really... depends what you use the phone for. For the most part tell it to use lower clock speeds when you don't need them so much (when phone is off, during the night, during call etc) but you will really notice the speed difference if it's underclocked while you use it, so I tend to allow it to use full whack when screen is on, unless the battery is low.
I also set up profiles to make things like Bloons TD4 run in performance mode and min of 1000mhz, to keep them smooth . Drains the battery though!

lol setcpu does a really good job at battery saving. When using ondemand, my phone can last more than 2 days (if it's on standby)
Have you guys tried under-vaulting? What does it rlly do?

kazemagic said:
lol setcpu does a really good job at battery saving. When using ondemand, my phone can last more than 2 days (if it's on standby)
Have you guys tried under-vaulting? What does it rlly do?
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If you mean decreasing the voltage on the CPU, no I haven't. From my experience in desktop PCs however, if the CPU voltage is too low it can lead to hardware issues and instability.
If something needs a certain amount of power, and you give it less, it will either try and draw more amps which increases heat and can fry components, or won't work properly. You could probably "under-volt" the CPU at the same time as reducing the clock speed however, but your performance will suffer. When the processor is set to be ondemand it underclocks itself when not in use anyway
The biggest battery drain is screen and radios, concentrate on using them less. Underclocking the CPU will make the phone last longer when in use, but usability will suffer and turn your super fast smart phone into a sluggish one. I only make mine stay underclocked when the screen is off, during a call, or on low battery. During general use I let it do its thing .

UV(Under volt) is actually not to bad. Don't ever set those values at boot, else when they are too low, it will cause BOOTLOOPS. It just reduces the amount of power allowed for the cpu to use, thus it won't use more than required. You can't really ask a person for his/her uv values, as no 2 chips are created equal.
People stating that they UC(underclock) their device is not quite right. We don't have much control over our cpu's to be honest. If you run tegra stats whilst using you're phone, you'll see what I mean. It will sometimes(happens quite often) just bump up to higher frequencies to which you UC them. Also as soon as the screen is locked and unlocked the max cpu frequency set by the governor will just return(for example: say stock is 1500mhz, and you set it to 1400mhz, it will return to 1500mhz after an unlock). Ondemand is very very good for battery and performance. But remember you have to tweak those values individually in order to optain the best possible performace for the given task you want. Whether it is for battery or performance.
It's actually also a lot better to just tweak those values as to TRY and uc. Uv will stick, UC not!
Here is a small example as to battery saving and performance values for ondemand governor:
sampling rate:---------60 000 ----- 30 000
up threshold:--------------95 ----- 60
sampling down factor:-------2 ----- 8
powersave bios: ------------3 ----- 0
ignore nice load:------------0 ----- 0
io is busy:------------------0 ----- 0

SetCPU Profiles

A couple weeks ago, I installed SetCPU to help with battery life. It did great! But, I didn't see the amazing improvement that I thought I would.
So, I did some research and found out about Profiles. Profiles are settings that you can make that will be applied when certain conditions are met.
Below are the profiles that I have created on my Nitro. I have seen 11 to 12 hours of medium use from my phone with these settings. If you have any suggestions on changes, please let me know. I'd like to find the absolute best settings and share them for everybody.
Profile Name: Screen Off
Conditions: Screen Off
CPU Max: 384Mhz
CPU Min: 192Mhz
Governor: powersave
Priority: 90, Exclusive
Profile Name: Charging Any
Conditions: Charging Any
CPU Max: 1512Mhz
CPU Min: 192Mhz
Governor: ondemand
Priority: 85, Exclusive
Profile Name: In Call
Conditions: In Call
CPU Max: 810Mhz
CPU Min: 192Mhz
Governor: ondemand
Priority: 80, Exclusive
Profile Name: Battery <= 10%
Conditions: Battery <= 10%
CPU Max: 594Mhz
CPU Min: 192Mhz
Governor: conservative
Priority: 75, Exclusive
Profile Name: Battery <= 25%
Conditions: Battery <= 25%
CPU Max: 972Mhz
CPU Min: 192Mhz
Governor: conservative
Priority: 70, Exclusive
Profile Name: Battery <= 50%
Conditions: Battery <= 50%
CPU Max: 1242Mhz
CPU Min: 192Mhz
Governor: ondemand
Priority: 65, Exclusive
Profile Name: Battery <= 75%
Conditions: Battery <= 75%
CPU Max: 1350Mhz
CPU Min: 192Mhz
Governor: ondemand
Priority: 60, Exclusive

By setting the profiles base on battery percentage like that, you are sacrificing the speed to improve battery life. It works in some cases but has side-effect in many other cases:
- Firstly, for some tasks that requires high CPU, apparently you need more time at lower speed, so power consumption for CPU is the same but more power needed for longer screen on -> worse battery life
- Secondly, the more profiles you use, the longer it takes for SetCPU to decide and change CPU speed, so the responsiveness is lower
For you screen off profile, if you use powersave governor, your CPU always runs at min speed, so setting the max speed at 384 MHz is meaningless.
For me, the only profile I use is the screen off profile with min = 192MHz, max = 432MHz, governor = ondemand, so that my phone will wake up faster when there's a call (otherwise you will have to wait a little bit before you can sliding Answer/Reject)

noemtfj said:
By setting the profiles base on battery percentage like that, you are sacrificing the speed to improve battery life. It works in some cases but has side-effect in many other cases:
- Firstly, for some tasks that requires high CPU, apparently you need more time at lower speed, so power consumption for CPU is the same but more power needed for longer screen on -> worse battery life
- Secondly, the more profiles you use, the longer it takes for SetCPU to decide and change CPU speed, so the responsiveness is lower
For you screen off profile, if you use powersave governor, your CPU always runs at min speed, so setting the max speed at 384 MHz is meaningless.
For me, the only profile I use is the screen off profile with min = 192MHz, max = 432MHz, governor = ondemand, so that my phone will wake up faster when there's a call (otherwise you will have to wait a little bit before you can sliding Answer/Reject)
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I haven't seen any responsiveness problems... And I'd actually like having a phone that I don't have to charge ever 3 hours over one that is unnecessarily fast.

mattman86 said:
I haven't seen any responsiveness problems... And I'd actually like having a phone that I don't have to charge ever 3 hours over one that is unnecessarily fast.
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His point was that scaling your CPU back so significantly isn't necessarily going to give you better battery life, and may even make it worse. When the phone is running at a slower speed, it takes longer to do certain things, which means your CPU/screen will be turned on for longer. Of course it entirely depends on what you're doing on the phone.
I think you might get just as good battery life by using interactive 1.2GHz all the time. People assume governors like interactive will destroy their battery but you'd be surprised.

mattman86 said:
I haven't seen any responsiveness problems... And I'd actually like having a phone that I don't have to charge ever 3 hours over one that is unnecessarily fast.
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If you have to charge your phone every 3 hours without SetCPU then I suggest you buy a new phone or new battery rather than playing with SetCPU

drumist said:
His point was that scaling your CPU back so significantly isn't necessarily going to give you better battery life, and may even make it worse. When the phone is running at a slower speed, it takes longer to do certain things, which means your CPU/screen will be turned on for longer. Of course it entirely depends on what you're doing on the phone.
I think you might get just as good battery life by using interactive 1.2GHz all the time. People assume governors like interactive will destroy their battery but you'd be surprised.
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I don't do much with my phone in the way of heavy gaming or video watching. I am going off of the last couple days of having SetCPU enabled and getting almost 15 hours of medium use out of my phone.
noemtfj said:
If you have to charge your phone every 3 hours without SetCPU then I suggest you buy a new phone or new battery rather than playing with SetCPU
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It was an arbitrary number.
Does anybody find this kind of post meant to make peoples phones better helpful? It seems like every time I post something that I personally have found to make the Nitro even more awesome gets a tone of comments basically telling me that none of it will ever work. I'm sure that if people would just try the things I post, they would be happy.

my setcpu setting-> uninstall
i found it did more harm than good. jd ultimate handling screen dimming&wifi with simple ondemand gov works much better for me.

scott0 said:
my setcpu setting-> uninstall
i found it did more harm than good. jd ultimate handling screen dimming&wifi with simple ondemand gov works much better for me.
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That what I've heard also... But I found that JD ran my battery down in about 6 hours without me even touching it one day.
If you have any suggestions on settings for it, I'd love to give them a try.

mattman86 said:
That what I've heard also... But I found that JD ran my battery down in about 6 hours without me even touching it one day.
If you have any suggestions on settings for it, I'd love to give them a try.
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yeah, i guess it's diff for everybody, just like the roms eh, some get great batt perf on 1 and sucky on another and someone has exactly opposite.
anyhoo, my jd ultimate settings are
Status
advanced profile
graphical notification->quickbox
Controls
wifi enabled->wifi preferred
brightness min 20% mid 45% max 150% (gotta get the most of this screen in the sunlight!)
light sensor fast
cpu min 192 mid 918 max 1512
governor ondemand
schedules
none, i also turned off night schedule as i have the phone plugged in during those hours.
triggers
Apps enabled
Configure->configure apps allow on during screen off->pandora
Location enabled
****************i find it makes a world of difference to give jd =>3 days to get it all right.
make sure setcpu is out of the way as well.