Develop Bugs

SetCPU saving power potential?

Heya,
I've heard of this SetCPU program, and figured it has some solid potential of saving battery power.
My question is - does it work? I've read several post claiming that SetCPU doesn't work on HTC phones.
If it does - will using the "Mix \ Max frequency" mode will save battery during stand by and normal usage, or just slow down the phone?
Using Rooted Desire, LeeDroid 2.2d.

Its primary use is to overclock the CPU, its secondary use is to create profiles and reduce the clock or change the governor. This will improve battery life slightly but also decrease responsiveness, depending on how far you go.
You'll need root if you want to use it.
To really increase battery life you have to use a custom ROM with an undervolted kernel.

So you're saying that the saving in battery life is insignificant considering the slowdown in performance?

yes, you use LeeDroid which is undervolted, thus perfect conditions.
It also uses a custom governor 'Smartass' which gives you best performance while using it and limits the max. clock while sleeping. That's the most common method to increase battery life with SetCPU while maintaining performance. So no, you don't need SetCPU, LeeDroid handles everything perfectly already.
However, the Desire has a very powerful CPU, compared with other Smartphones. So you can use SetCPU to limit the clock to maybe 700MHz or 800MHz. This will increase the battery life but also reduce the processing power. If you don't play games, don't do a lot of simultaneous things or browsing huge websites, don't use heavy loaded homescreens, it's possible that you don't notice the reduced processing power.

Thanks again
I guess there is no damage to the SnapDragon if I lower clock speeds a bit...
But, if I want to do some overclocking - how far is it safe to go?
When I OC'ed my Q6600 CPU I used the TheremalRight Extreme 120 with two Slip Stream fans to cool it off.. So, will heat damage be a constant threat to an overclocked Desire?
I currently live in Israel, and it's hot as hell even on stock speeds

CoreOxide said:
Thanks again
I guess there is no damage to the SnapDragon if I lower clock speeds a bit...
But, if I want to do some overclocking - how far is it safe to go?
When I OC'ed my Q6600 CPU I used the TheremalRight Extreme 120 with two Slip Stream fans to cool it off.. So, will heat damage be a constant threat to an overclocked Desire?
I currently live in Israel, and it's hot as hell even on stock speeds
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I for one has chosen to disable the default powersave in Auraxt sense, and then using SetCPU to control it, i get a day of power easily, and still goes to bed wit 50% power, that is with stock clocks on normal usage, but with minimum power (245) on screen off

Re overclocking:
To reach high clock speeds you also increase the voltage on your PC, else you can't increase the frequency that drastically.
Because you can't improve the cooling on the desire you have to keep stock voltages but also can't overclock that much.
The overclocking methods on the desire keep the voltage at stock values or even lower (defrost rom).
I don't know the voltage values for LeeDroid.
I it shouldn't get warmer. In the worst case it will crash and reboot until you reduce the clock speed.
Sent from my HTC Desire using XDA App

[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.

[Q] Power Consumption and Clock Speed...

Question: if the kernel will go into deep sleep whenever it has nothing to do, what is the benefit in regards to power consumption of pinning the clock speed real low when the screen is off?
I ask because common knowledge, at least from what I've seen around, is that the low-clock "screen off" profile is common sense. But today I tried not having that profile, and I see that the CPU goes into deep sleep a lot more time now, and my battery life is the same if not actually better than before.
True, ROMs and kernels are still changing so much that it's difficult to dedicate enough time to one configuration to actually determine it's efficiency over time, which is why I wanted to throw this out here, see if anyone with more knowledge can answer.
If the CPU is under a certain amount of load, I would imagine that, for instance, in an Ondemand governor with a very low Up Threshold, the CPU will spike to a high speed until it's done, then sleep the rest of the time until the next load. If constrained to a low clock speed, it'll work on it, slow but steady, until it's done.
Is the high voltage required for that spike offset by the voltage savings of going to sleep, and is the total voltage consumption at the end of the load lower than the alternative, that is, stick to a low clock cycle, consuming what I assume is lower voltage, but for a longer amount of time? Is voltage consumption as clock cycle speed increases linear, or exponential?
If the power consumption increases exponentially as clock speed increases linearly, then it might be better for power consumption to restrict the processor to lower speeds. But if power increase is linear, then it would be better, I believe, to let the CPU finish with it's load as fast as it can, so it can go to sleep faster.
Any thoughts, ideas?

To Quote from Wikipedia's Overclocking page:
Increasing the operation frequency of a component will usually increase its thermal output in a linear fashion, while an increase in voltage usually causes heat to
increase quadratically
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I know nothing about the Galaxy S II specifically, but most Android phones scale both voltage and clock-speed together, leading to exponential power increases when clocking up. Thus, in theory, you should see better battery life with a lower CPU limit with screen-off.
If in your case you have constant voltages across the board, that would explain why you see no benefit from a screen-off profile.
Finally, if you do have constant voltages across clock-speeds, then you probably could lower your voltages at lower speeds and thus realize a benefit.
YMMV, of course

Yes but if you have processes running in the background like large file downloading then the phone won't be able to process any of them
Sent from my SGH-T989 using xda premium

CPU voltage power usage

Quick questions:
1) Is power usage by the CPU DIRECTLY affected by voltage? For example, does 1V use twice the power of 0.5V? ...or is it not a linear response like that?
2) Does the frequency (at same voltage) influence power usage by the CPU? Ex. 1.0GHz vs 1.1GHz, both at 1V.
Sent from my LG-P930 using Tapatalk 2

yes no

Flyview said:
1) Is power usage by the CPU DIRECTLY affected by voltage? For example, does 1V use twice the power of 0.5V? ...or is it not a linear response like that?
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Yes, it's linear. The formula is P=I*V where P is power, I is current, and V is voltage.
2) Does the frequency (at same voltage) influence power usage by the CPU? Ex. 1.0GHz vs 1.1GHz, both at 1V.
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Yes, definitely, because when running at a higher frequency, the CPU will be drawing more current (see above formula). That's the whole reason that CPUs will slow themselves down when not needed.

drumist said:
That's the whole reason that CPUs will slow themselves down when not needed.
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When idle, CPU's slow down not only frequency but voltage too. Thats why cpu's consume less energy on lower frequencies. Processor on the same volgate, but different frequencies consumes almost the same power.

-ReaL- said:
When idle, CPU's slow down not only frequency but voltage too. Thats why cpu's consume less energy on lower frequencies. Processor on the same volgate, but different frequencies consumes almost the same power.
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Dynamic power consumption is directly (linearly) affected by frequency, but static (leakage) power consumption is a different beast. I may be overestimating how big the dynamic power consumption is in comparison to static with these tiny SoCs.

drumist said:
Yes, it's linear. The formula is P=I*V where P is power, I is current, and V is voltage.
Yes, definitely, because when running at a higher frequency, the CPU will be drawing more current (see above formula). That's the whole reason that CPUs will slow themselves down when not needed.
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Yes, that's what I'm wondering. Is the voltage and current increased with higher frequency or just voltage? If just voltage then the power use of any two frequencies at the same voltage is the same. If current also changes based on frequency, then two frequencies at the same voltage would use a different amount of power.
Sent from my LG-P930 using Tapatalk 2

Flyview said:
Yes, that's what I'm wondering. Is the voltage and current increased with higher frequency or just voltage? If just voltage then the power use of any two frequencies at the same voltage is the same. If current also changes based on frequency, then two frequencies at the same voltage would use a different amount of power.
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No, current increases with frequency. But there is also a certain amount of power that is consumed no matter what the frequency is (so having a very low frequency doesn't mean it's consuming almost no power -- it just means it's consuming LESS power). I'm kind of oversimplifying it in my last post. It's complicated stuff, and I don't claim to be an expert at it. I'm just an amateur.
---------- Post added at 02:54 PM ---------- Previous post was at 02:13 PM ----------
I've been researching this a little bit since I have some free time and it caught my interest. Here's what I've come up with:
P ≈ k₁·V²·f + k₂·V
k₁ and k₂ are constants. (They have meaning but it's not necessary that we understand them.) V is voltage, and f is frequency. The first term (k₁·V²·f) is dynamic power, and the second term (k₂·V) is static or leakage power.
Some things to take away from this is that power consumption is more than halved when the voltage is halved. Even though it would appear that reducing the frequency only influences the dynamic power, the CPU automatically scales the voltage down when the frequency is lower, so as a chain reaction, the static power is also reduced significantly. (And as it happens, the static power is larger than dynamic power with modern chips, so that's important.)
Again, I'm not an expert on this. If someone sees an error or misunderstanding let me know.

Where is current in your formula? I know the CPU has voltages you can set for each frequency, what you would call the static voltage, but what is this dynamic power? Let's say I run the phone at 1.51Ghz at 1087.5mV. Would it consume more power than running at 1.35Ghz, if also set at 1087.5mV?
Sent from my LG-P930 using Tapatalk 2

Flyview said:
Where is current in your formula? I know the CPU has voltages you can set for each frequency, what you would call the static voltage, but what is this dynamic power? Let's say I run the phone at 1.51Ghz at 1087.5mV. Would it consume more power than running at 1.35Ghz, if also set at 1087.5mV?
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The current is incorporated in the frequency term. The reason the dynamic power term has frequency in it is because the current drawn is proportional to the frequency. Basically, current equals frequency times a constant, which was absorbed into k₁.
Yes to your last question, but it may not be a huge difference.

minimum cpu speed question

Have a question regarding min CPU speed vs voltage. I run task's Roman with stock kernel. My phone is not stable unless I up the voltage on the CPU clock at both the 189 and 378 speeds to 925mv.
So here's the question... since both speeds use 925mv, wouldn't it make more sense just to leave the min CPU speed at 378? Seems to me the faster min speed would process faster allowing the phone to go into deep sleep faster and saving battery.
Thoughts?

192 and 384, you mean?
Personally, I prefer my min at 192 not cos of mV difference, but cos it keeps my phone lots cooler when at min speeds.

I asked a similar question with no response. mine goes down to 81mhz and stays stable but a higher clock speed uses the same voltage so I thought just run the higher one. unless deep sleep is consistent then it shouldnt matter. but for cases like bluetooth or music streaming the higher speed might seem better. but the more heat thing must cause more battery usage I would think

s384 said:
I asked a similar question with no response.....
....more heat thing must cause more battery usage I would think
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Looks like some thread lost with time...
More heat isn't good... heat is nothing but energy dissipated... and that means energy lost... So more heat is an indicator that you are kinda pushing your CPU to work hard and harder the work, more the battery utilized.

The voltage consumption of a CPU is calculated by f*V^2. So to answer the question, even if two frequencies share the same voltage, the lower frequency will still consume less power than the higher frequency.
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