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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
hi,
I am running stock jellybean with franco kernel. just wondering what is the optimal CPU setup that doesnt sacrifice too much performance while increasing battery life. Im not too concerned about games as I rarely play them. I ussualy use the phone for music, calls, text, email, and webbrowsing.
I am using the Franco updater app. I have 1228 max, 230 min
and screen off max is 384.
I also noticed in cpu spy that my highest two frequencies 1036, 1228 are combined less than 10%.
with all that information, what do you suggest?
hshaikh said:
hi,
I am running stock jellybean with franco kernel. just wondering what is the optimal CPU setup that doesnt sacrifice too much performance while increasing battery life. Im not too concerned about games as I rarely play them. I ussualy use the phone for music, calls, text, email, and webbrowsing.
I am using the Franco updater app. I have 1228 max, 230 min
and screen off max is 384.
I also noticed in cpu spy that my highest two frequencies 1036, 1228 are combined less than 10%.
with all that information, what do you suggest?
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Click to collapse
I suggest to decrease your max CPU until you feel it affects performance too much. You can also try switching to a governor less aggressive than interactive (try ondemand).
Don't expect magic though. I've played with decreasing max CPU clock, max CPU screen off, governor settings etc with three different kernels. Gathered stats for at least one week each time. Never noticed a difference large enough to actually matter to me. For maximizing battery life, you can gain more by hunting apps that cause a lot of (partial) wakelocks and alarms, and use low screen brightness.
hshaikh said:
and screen off max is 384.
with all that information, what do you suggest?
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Click to collapse
don't limit screen off cpu speed to 384. it will take longer to perform operations under wakelock, thus killing of more battery than it actually saves.
it would be nice if listening to music, since it's not an intensive task and it requires constant cpu usage. still, you'll most likely have stuff syncing in the background so i don't think you're doing any good by limiting it to 384 on screen off.
power isnt going to be conserved with lower clock speed. lower clock speed means it takes longer to finish the task. to conserve power, your phone has to do less. for example, lower brightness, no sound, less/no syncing.
Darunion said:
power isnt going to be conserved with lower clock speed. lower clock speed means it takes longer to finish the task. to conserve power, your phone has to do less. for example, lower brightness, no sound, less/no syncing.
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Well, there is an optimum somewhere. Higher CPU speed means tasks are executed more quickly, but higher clock speeds also draw more current from the battery. I agree that tweaking this has little effect on battery life though.
Petrovski80 said:
Well, there is an optimum somewhere. Higher CPU speed means tasks are executed more quickly, but higher clock speeds also draw more current from the battery. I agree that tweaking this has little effect on battery life though.
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you are correct. there is a magic middle ground because power consumption doesnt scale in a linear way. but finding that spot would take massive testing and even getting to the center, would still probably only gain about 10-15mins average use on a battery charge :/
bk201doesntexist said:
don't limit screen off cpu speed to 384. it will take longer to perform operations under wakelock, thus killing of more battery than it actually saves.
it would be nice if listening to music, since it's not an intensive task and it requires constant cpu usage. still, you'll most likely have stuff syncing in the background so i don't think you're doing any good by limiting it to 384 on screen off.
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what speed show i set to max when screen is off.
did you read anything that Darunion and Petrovski80 wrote? I keep mine at it's max, i don't care, i don't live in the woods with no electricity.
thanks for your inputs. i have experimented and I found out that changing the cpu speeds has minimal effect of battery life. the clock speed is not killing the battery the screen is. no matter what cpu settings i use i get 3-4 hours screen on time.
if i dont use the phone alot that day (like 1 hour screen on time) the battery will still be 40% after a day.
hshaikh said:
thanks for your inputs. i have experimented and I found out that changing the cpu speeds has minimal effect of battery life. the clock speed is not killing the battery the screen is. no matter what cpu settings i use i get 3-4 hours screen on time.
if i dont use the phone alot that day (like 1 hour screen on time) the battery will still be 40% after a day.
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Exactly. I get similar performance.
Sent from my Galaxy Nexus using Tapatalk 2
Lowering the coltage can help with heat and battery.I flashed the ElementalX kernel,but flar2 didn't tell much about lowering the voltage.
My PVS number is 3,so how much voltage should be lowerd?Not only the minimum,but also others.
I may lower it too much(-100mv),then I got a reboot while playing videos.
Thank you
a1317931279 said:
Lowering the coltage can help with heat and battery.I flashed the ElementalX kernel,but flar2 didn't tell much about lowering the voltage.
My PVS number is 3,so how much voltage should be lowerd?Not only the minimum,but also others.
I may lower it too much(-100mv),then I got a reboot while playing videos.
Thank you
Click to expand...
Click to collapse
Check this guide
http://forum.xda-developers.com/showthread.php?t=2469261
a1317931279 said:
Lowering the coltage can help with heat and battery.I flashed the ElementalX kernel,but flar2 didn't tell much about lowering the voltage.
My PVS number is 3,so how much voltage should be lowerd?Not only the minimum,but also others.
I may lower it too much(-100mv),then I got a reboot while playing videos.
Thank you
Click to expand...
Click to collapse
Overclocking will effect the heat too. The Voltage can be adjusted but most of the time don't need to be fooled with.
Sent from my Nexus 7 Flo running CM 11 4.4.2 with ElementalX Kernel using XDA Premium 4 mobile app
There is very little effect on battery by lowering the CPU voltage. There is a thread somewhere here on XDA where they do out the math and the energy savings from reducing CPU voltage are like 1% or something super low like that. The CPU uses very little power when you compare it to everything else in the tablet, like the 1080p screen, wireless, etc etc etc. Additionally, the overall power used by the CPU is based on both the clock speed and voltage, with high clock speeds being the major contributor to power consumption. Using a power scheme which does not ramp the CPU frequency as quickly or even underclocking the cpu will yield much greater power savings and heat reduction than voltage reduction ever will.
Hnk1 said:
Check this guide
http://forum.xda-developers.com/showthread.php?t=2469261
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well,I mean,the volatage of CPU,not the battery...
anyway,thank you
LinearEquation said:
Overclocking will effect the heat too. The Voltage can be adjusted but most of the time don't need to be fooled with.
Sent from my Nexus 7 Flo running CM 11 4.4.2 with ElementalX Kernel using XDA Premium 4 mobile app
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I just use the stock frequency.I like reading,high performance isn't needed,so I just want to increase some battery life,some people in tieba told me that lowering cpu voltage can make some great help...
skrypj said:
There is very little effect on battery by lowering the CPU voltage. There is a thread somewhere here on XDA where they do out the math and the energy savings from reducing CPU voltage are like 1% or something super low like that. The CPU uses very little power when you compare it to everything else in the tablet, like the 1080p screen, wireless, etc etc etc. Additionally, the overall power used by the CPU is based on both the clock speed and voltage, with high clock speeds being the major contributor to power consumption. Using a power scheme which does not ramp the CPU frequency as quickly or even underclocking the cpu will yield much greater power savings and heat reduction than voltage reduction ever will.
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oh,it make sense,some people in tieba told me that lowering cpu voltage can make some great help with heat and battry life,look like they misled me,I have nerver noticed the diffrences in heat and battery, only the unstability is obvious...
thank you
skrypj said:
There is very little effect on battery by lowering the CPU voltage. There is a thread somewhere here on XDA where they do out the math and the energy savings from reducing CPU voltage are like 1% or something super low like that. The CPU uses very little power when you compare it to everything else in the tablet, like the 1080p screen, wireless, etc etc etc. Additionally, the overall power used by the CPU is based on both the clock speed and voltage, with high clock speeds being the major contributor to power consumption. Using a power scheme which does not ramp the CPU frequency as quickly or even underclocking the cpu will yield much greater power savings and heat reduction than voltage reduction ever will.
Click to expand...
Click to collapse
Especially with all things considered, the CPU is mostly loafing along. It doesn't start drawing power until it's being asked to work. Lowering the voltage is asking for a laggy device when the chips are down.
I highly suggest lowering the Cpu clock speeds if you want to affect the heat and battery. Lowering the cap speed for the device doesn't allow it to work hard enough to reach speeds to really make it toasty. Same goes with battery life. For example, I'm sure that you can walk much farther than you can run.
Changing the voltage is the equivalent of running down a new street...you have to test and test before you find a good voltage. Every device is different. Someone else's device might do great with the exact same settings that are making your device reboot. Do a lot of reading if you are certain that you want to change the voltages.
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Nice - i can confirm that the battery is great. Never has a phone with such good battery life.
But sometimes i wish i could deactivate all energy saving options, because from time to time it seems that some apps lost the possibly to wake up from standby.
Just as the title says. My Samsung Galaxy S10+ tends to heat up less when I play heavy games like PUBG while charging compared to when I play unplugged. I have the exynos version on latest stock firmware. My fast cable and wireless charging is on and I only use 4G data (no wifi). To my understanding it should be the other way, i.e. heat up more while charging and playing! Anybody else notice this? Any views and suggestions as to why this would happen are welcome.
In theory your phone would be pulling power directly from the fast charger therefore having more current available. Normally when your going off of battery power playing resource intensive games like PUBG run you CPUs at max frequency causing more heat. When the CPUs run that speed they also use more power sometimes more than the battery is ment to run at continuously causing the battery to also heat up. So using direct power reduces the amount of heat production.
As we see in "Gaming" phones like the ROG branded one they use better cooling methods like water and gas(usually hydrogen) based cooling.
jwarrior319 said:
In theory your phone would be pulling power directly from the fast charger therefore having more current available. Normally when your going off of battery power playing resource intensive games like PUBG run you CPUs at max frequency causing more heat. When the CPUs run that speed they also use more power sometimes more than the battery is ment to run at continuously causing the battery to also heat up. So using direct power reduces the amount of heat production.
As we see in "Gaming" phones like the ROG branded one they use better cooling methods like water and gas(usually hydrogen) based cooling.
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Thanks! Makes sense to me. But this would also mean that it's possibly better for the battery that way (playing while charging). It's definitely heating up a lot less! Will have to wait and see.