Hey guys. i'm using Solarflare rom and it uses snowleopard kernel. What's the right settings to undervolt it? I want to extend my battery life more. I tried to change the values in the undervolt settings but the phone always hangs.
actually i want to know those settings too, my battery seems to be running out so quickly.
Actually SetCPU UV settings are different from phone to phone, you have to find your own good settings. Just start running a day with -25mV on the different speeds and see if it's stable and if so lower it another -25mV the next day etc...
And if you are running out of battery too quickly try to set a screen off profile 200-500MHz with a conservative governor. Also try to recalibrate your battery if you have not done that, that may work wonders on your phones. What kind of battery times are you getting ? Screentime ?
Like Reidar said it's different for every device. Right now I'm using Ninphetamine v2.05 and I'm UC @ 800mHz. With UV I have it at -125mV for 800mHz, 500mHz, and 200mHz with a conservative screen off profile. Been running this for a while now and it has been stable.
A quick tip, if you want to see if a new voltage is stable quickly is to set the voltage and run a stress test in setCPU. And always remember to uncheck the Set on Boot box when testing voltages or even CPU speeds.
Sent from my Galaxy S II using MIUI
With my GS2 i use screen off profile on demand 200Mhz with undervolt of 800mV and work very nice, only thing is a 0,5 sec lag when i unlock my phone
http://forum.xda-developers.com/showthread.php?t=1158102&highlight=SetCPU
Just one simple question. When phone is in deep sleep, the cpu's running speed is the min frequency I choose from the cpu settings or a default lower one?
I use smart ass 2 with min at 768 and max at 1516 . So in deep sleep my phone is running at 768?
Thanks in advance...
Sent from my Huawei u8800 using XDA Premium App
spirosbond said:
Just one simple question. When phone is in deep sleep, the cpu's running speed is the min frequency I choose from the cpu settings or a default lower one?
I use smart ass 2 with min at 768 and max at 1516 . So in deep sleep my phone is running at 768?
Thanks in advance...
Sent from my Huawei u8800 using XDA Premium App
Click to expand...
Click to collapse
Not 100% sure but freq is minimum as it can be. And if cpu is not used no metter is freq 10000MHZ or 300Mhz it uses almost the same power. But when cpu is in use freq is important to power usage. Freq management is good not because it lowers freq but because it lets use lower freq on things that is not require hi freq. so it saves LITTLE LITTLE BIT of power. In idle mode (deep sleep) no meter what freq is.
But i still don't understand the need of governor. It's good only in cases where you overclock cpu but if don't - i don't see why it should be used.
PS Use app called CPU SPY it shows on what freq your cpu is being used and how much of the time.
Thanks! I use CPU SPY and it says tha about 60% or more is in deep sleep, 15%-25% is at 768 and the rest higher, which seems to be a good thing. But my phone still lasts for about 10-15 hours with normal use.
So i thought that maybe my min 768 frequency drain a lot of battery.
To clear things up a bit I use latest oxigen rom+latest franco kernel+zram+Juwe ram script...
Actually deep-sleep state is a special state supported by your phone MCU. In this state, a lot of functionality (therefore a lot of logical gates) are disabled thus MCU consumes very low power compared to normal functioning states. The thing about a CPU/MCU is when it is running even if there are no work to do no code to process, it has to run some command. While idle it must run NOOP (no-operand / no operation) command or do something equally unnecessary like counting a not required number. But in deep sleep mode, MCU actually stops working except for core functions to keep your phone going on.
Think about it this way, in a normal working state, CPUs most basic functionality is to read a command from memory, execute it and proceed to the next command to continue. Thus, in an operating system or a single purpose embedded software, CPU/MCU has to execute a "do nothing" command when you have no job to give it. But even a "do nothing" command need all of the MCU/CPU resources to be kept readily available. If you're sure that you have absolutely no job for your MCU/CPU to do, what you can do is to tell it to go and sleep fr a while until you wake it up again. In sleep, MCU/CPU can shut down a lot of its support systems like math processing, external memory access, graphics related functions (if any), even IO outputs. Depending on your CPU/MCU, this means until an interrupt occurs or a special sub system wakes it up, most of the sub-systems within your MCU/CPU thus may be millions of transistors will not be working so, your CPU/MCU will not consume as much power.
In layman's terms, deep-sleep state is a special state that shut down most of your MCU in your phone, thus while crippling it by removing its ability to function, making sure that it doesn't consumes much power. So OS (Android) (with the help of some additional hardware) controls when your MCU will sleep and under what circumstances it will wake. So it shuts down the engine -so to speak- when you're not using it for long terms and saving fuel rather than leaving your car on idle.
Hope this helps..
Thanks t_d_z. That is also how I imagined things...
But what is wrong with my battery which today, for example, went 33% down in 5 hours with 68% (from cpu spy) in deep sleep, without wi-fi on.
As i said above, I use latest oxigen rom+latest franco kernel+zram+Juwe ram script+smarass2 governor...
I also calibrated my battery by wiping battery stats, like i read in a post.
I have read in an other forum that if you use smartass (I use smartass2) or ondemand (I think...) governors, the governor is learning your habits and after a week you see the difference. Is that true?
Finally, can you guys who have "good" battery life, post your settings? (By settings I mean: rom, kernel, governor with cpu parameters, how you use the phone and everything else you think is important).
Thanks again...
I get about two days of battery life. I use Oxygen without any modifications. CPU is min. 245 (or something like that with 200, I dunno now) and max. is 800. Wifi is always on when I am home.
Try installing Oxygen-r1 and use it with a full battery, do not change anything and do not install too many apps. There will be apps that just won't stop running (like BBC or CNN app), I do not install those. Then you will see how long your battery lasts. If you just write some messages throughout the day and call somebody for 1-3 hours you should get about 2 days.
Then install your apps and test it again - maybe your apps are the problem.
spirosbond said:
Thanks t_d_z. That is also how I imagined things...
But what is wrong with my battery which today, for example, went 33% down in 5 hours with 68% (from cpu spy) in deep sleep, without wi-fi on.
As i said above, I use latest oxigen rom+latest franco kernel+zram+Juwe ram script+smarass2 governor...
I also calibrated my battery by wiping battery stats, like i read in a post.
I have read in an other forum that if you use smartass (I use smartass2) or ondemand (I think...) governors, the governor is learning your habits and after a week you see the difference. Is that true?
Finally, can you guys who have "good" battery life, post your settings? (By settings I mean: rom, kernel, governor with cpu parameters, how you use the phone and everything else you think is important).
Thanks again...
Click to expand...
Click to collapse
Look not at cpu spy but in battery usage to find out what drains your battery. And i can tell All roms are kinda lame in terms of battery, except CM7. In deep sleep it takes about 7% of battery in 10hours. I tried all roms but non of them was so efficient. But latest franco kernel (which i think even more improves cm7 rom) does not support cm7 right now, so i've attached older version if you would like to test cm7+franco kernel.
With normal usage of 50 sms and 30minutes of calls and sometimes wi-fi to download few apps and 20minutes on easy games my battery lats about 18hours. Whan only sms it lasts 30hours. depends how long lcd is on
Well, I'm not an expert on smart phone OSes but I'm an expert on embedded systems and micro controllers. If the designers are not really stupid (which I'm sure they are not) all the peripherals gets suspended when the main CPU goes to deep sleep mode. So, it is almost impossible for the phone to consume much power in deep sleep state. Most likely your phone consumes that power the rest of the time when it is not in sleep mode. I agree with Tommixoft, you should use battery usage info rather than CPU spy to find what drains your battery. Also, here is a quick check list about what consumes power :
1. Screen, especially when it is brightly lit
2. GSM network (Even when you're not talking to phone, GPRS/Edge/3G network communications drains almost as much power)
3. Wireless network
4. GPS
As an additional note, if your phone is not going to sleep mode regularly try to uninstall applications that have "prevent phone from sleeping" security setting.
Hope this helps, and of course there are a lot of more experienced people in the forum that knows about the details of the kernel so they might provide additional info.
Regards,
---------- Post added at 05:15 PM ---------- Previous post was at 05:10 PM ----------
Oh I forgot to tell the MOST important thing, 768MHz is way too high a value to set as minimal frequency. Try to set it 245. I use 122 MHz and it work pretty well. Don't forget, when you need the CPU power, the governor will provide it for you.
1. Abstract
2. Approach
3. Baseline configuration and results
4. References
5. Disclaimer
1. Abstract
Initially I was quite dissapointed with the battery life of the Samsung Galaxy S II i9100 with Android 2.3.4 out of the box. Coming from the Symbian world Nokia E71 I have been used to 6-7 days without recharging, while on SGS2 I got barely 1.5 days of normal usage. I started to optimize, and felt that the hardware is very capable for power saving, but the software is not optimized. After turning off all synchronization, going thru every program settings to switch to manual sync, switching to 2G network (EDGE in my area), turning off WiFi/Data/GPS/Background data I've got a busy day full of meetings at work (didn't touch the phone apart from 2 incoming calls and a few notes) and only 10% decrease of battery for 24h (100%->90%) which is amazing by itself. But I wanted to optimize more.
I have heard that other things like Custom ROM, freezing of system applications, task killers, Under Volting (UV), Under Clocking (UV) would help me too, but I was about to discover which one really helps in real use.
One lazy Sunday like today while being a bit sick allowed me to conclude an experiment of how far did I get in optimizing the power usage for a "baseline configuration" - WiFi/Data/GPS/Background data off, 2G network, all possible sync to manual - and the results are astonishing.
2. Approach
The approach to optimize the battery life is only one - PUT IT TO SLEEP AND DON'T LET IT AWAKE.
Having read a ton of articles on xda-developers.com and other places I have concluded that the strategy for optimizing includes these major steps:
2.1. Get a clean baseline Custom ROM where much of the "bloatware" is removed, so you have less to optimize - optional step but it helps to do it
This probably helps although not necessary. I'm not sure if the stock ROM will allow you to put custom kernels which will be needed in the next steps to optimize further.
But in any case you need to be at least "rooted" to apply some of the advice - either via a rooted kernel like CF-Root [8], or via an exploit like the DooMLoRD'a zergRush exploit [7].
2.2. Optimize the screen-on time
This is up to how frequently you use the phone
What you can optimize is to set a default "conservative" CPU Governor profile from 200MHZ to 1200MHz for regular usage - nothing really special, it's only slower on jumping to high frequencies.
If you have a kernel like RedPill Kernel [9] you can add an additional In-Call profile with "conservative" CPU Governor from 100MHZ to 800MHz - while you talk and phone to the ear it idles at 100MHz, but if you start a let's say Notes taking application, or go to turn on Bluetooth it will be snappy enough. Same holds true for listening to music or listening to books - but it's up to your imagination how to set a 100MHz profile in this case (maybe via Tasker). Have in mind that the 100MHz setting may be unstable on some phones because it's not standard, but mine is absolutely fine with that setting.
For setting the CPU profiles software like Voltage Control [5] (paid version for many profiles) is used.
CPU Governor "conservative" is crucial so you don't instantly jump to the highest frequency as it happens with the default "ondemand" governor (or its clones).
You can choose an I/O Scheduler appropriate for your CPU Governor based on the MagicConfig article in my references [14].
People also say that the following helps and I use it: turn off button LED lights, darker wallpapers, auto-rotation disabled, auto brightness on (I have to see the screen after all).
If you use kernel like RedPill Kernel [9] the button LED lights are undervolted by default, so you can leave them "on for 1.5s" for example.
If you have a Custom ROM like CheckROM Revolution HD V6 [10] with JKay Deluxe Settings you can set a Dark or Darker auto brightness profile - also usable to some extent.
One article in my references [12] also gives the power drain in milliwatts (mW) for each hardware device - go read it and you will understand how much the Amoled Display (Average - 370mW), LED lamp next to camera (1.3W), Camera (700mW), Bluetooth and GPS (110 to 180mW) etc. hardware actually consumes.
2.3. Optimize the screen-off time
2.3.1. Analyze Wakelocks
Wakelocks indicate when some application prevents the phone from going to sleep for some time. It does not necessarily mean that it does something significant at that time, and may be only a bad application design. Some applications really like to hold wakelocks periodically during the day for no reason, even if set to Manual sync etc. Examples of such applications are Facebook, 3G Watchdog... You milleage may vary but you can be sure that this hurts your battery life a lot. Any such application can be frozen with Titanium Backup or uninstalled if it's not a system application. Both count and total duration of the wakelocks are important.
BetterBatteryStats [1] has a screen to debug Partial Wakelocks and Kernel Wakelocks. You can also obtain the raw information via the console command "cat /proc/wakelocks".
2.3.2. Analyze Alarms
Alarms are a way to start jobs in the system at a predefined time. Many applications set alarms to get awaken and check/poll something before sleeping again. You should note that firing an Alarm is not necessarily connected to having a Wakelock - you can see many alarms firing but very few wakelocks. The problem is that too many applications set too many alarms for no reason. These activities also hurt your battery life a lot. Examples of such applications are Google Maps (at least for me)... As long as I have another GPS application with offline maps, I've simply frozen Maps with Titanium Backup. Another example was let's say Social Hub, but as long it was firing once per 24h, I didn't bother to touch it.
BetterBatteryStats [1] has a screen to debug Alarms which requires Root access. You can also obtain the raw information via the console command "dumpsys alarm".
2.3.3. Analyze Network Connections
If you get lost in the Wakelocks and Alarms, you can help yourself by checking what connections are kept alive while Internet is connected. OS Monitor [3] has a Connections screen which is equivalent to "netstat". This is also a good indicator what may be drawing unnecessary battery and respectively freeze/uninstall. In my case I can point that I've discovered that K-9 Mail had a bug with IMAP accounts - if I connect to an IMAP account set to manual/poll sync once, it keeps a connection open forever, until you restart or kill the process, but for POP3 account there is no problem... Being aware of such things really help with the battery life.
2.4. Optimize deep idle and sleep time
This is the most important goal in this article - how to get into deep idle/sleep and stay there, because this is the only real way to save energy on such a powerful device
CPU Spy [2] can show you how much time you spend in deep idle/sleep - with my baseline testing I've managed to get 99% deep idle/sleep which is amazing - only if the manufacturers gave us the phones in this state and we can build on that...! But it's the other way round.
Unfortunately the sleep mode on the stock kernel and the CF-Root kernel is not too deep. Entropy512 in my references [15] describes the following modes of idle/sleep:
IDLE - clock is gated but power remains (does not eliminate any static power consumption)
AFTR - clock is gated, CPU core power removed, cache power remains - this eliminates a great deal of static power consumption - cannot be entered if second core is active
LPA - AFTR + removal of cache power - cannot be entered if second core is active
IDLE is entered if the CPU is expected to be free for 4 msec (40 msec stock)
AFTR is entered if the CPU is expected to be free for 10 msec (disabled stock)
LPA is entered if the CPU is expected to be free for 40 msec (40 msec stock)
This compares to suspend, aka deep sleep, which takes around 150 msec to enter and 650 msec to resume, and the CPU must be at 800 MHz (or at least have enough voltage to support 800 MHz operation) during this time. Entering suspend/resume is very costly in terms of power due to heavy interrupt load.
Unfortunately my knowledge ends here, but flashing a kernel like RedPill [9] with Power Saving features and patches enabled improved the deepness of the idle/sleep very significantly, let's say 2 fold compared to the stock kernel. Sleep is entered faster and with more savings.
2.5. Optimize the modem/baseband
If all the points above are done, you can consider some savings from trying to flash newer modem/baseband compatible with your Custom ROM for better power savings during Calls and Data transmission. I did not get deep into this yet, but it's rather a big Voodoo, because the contents of the various modems are not public and you can only read feedback like "works very good for me" and "totally awful", which is not very scientific. Initially you can try staying with your original modem or the one provided by the Custom ROM, and optimize the previous points.
2.6. Optimize other stuff
2.6.1. Under Volting - will probably help, but for every frequency you need to choose voltages that are not too low to keep the phone stable. You can try the UV profile from the MagicConfig article from my references [14].
2.6.2. Under Clocking - I consider trying to use 100MHz useful for some scenarios, but only as an additional profile. After all the phone is very powerful and snappy to cripple it with 100MHz-1000MHz profile as default.
2.6.3. Automatic Task Killers - absolutely worthless peaces of software [16]. Android OS is good at power saving. It is very power saving conscious actually, of course combined with capable to sleep hardware. The only reason to kill a process is if it locked on holding some resource/connection forever, and OS Monitor [3] can kill it.
2.6.4. Battery charging - charge the battery as frequently as you want, but be sure to not keep it constantly on high charge (90-100%) [18], as long as this is not a good state for storage. Making bigger cycles helps to maintain better battery life. Some sources say cycling from 0% to 100% is not optimal [17], but from my experience through the years this way also works good for battery longevity, and maintaining small loss of capacity. I can give an example of losing up to 10% of battery capacity per year compared to design capacity with this method. You can view such statistics in Power Management tools in Lenovo ThinkPads etc.
Note that the battery indicator has some tweaks around 100% so consider the following:
- When charging for me it hops from 98% straight to 100%. If you disconnect now, it drops to 98% again, and this is what other people complain from too. Just wait some more time and it will charge to real 100% to have more battery life.
- The indicator stays at 100% longer than at any other value. So when testing, always test from the same baseline, e.g. always charge to 100% before comparing results.
3. Baseline configuration and results
CheckROM Revolution HD V6 PDA XWLA4 (Android 2.3.6) + modem XXKI4 (was XWKL1 but changed for no reason) + kernel RedPill 1.3.
WiFi/Data/GPS/Background data/Auto-rotation/Button LED lights - OFF
Any type of Sync or Polling - OFF/MANUAL, using local Contacts and local Calendar
Widgets - AccuWeather.com on MANUAL and Today view from Calendar.
Network: 2G (EDGE in my area)
Background and lock screen: Dark wallpapers
CPU default profile: conservative 200MHz-1200MHz
CPU in-call profile: conservative 100MHz-800Mhz
Because I don't want to wait a full day for the statistics, I'll post now for 8 and 12 hours, and tomorrow add for 24 hours.
(See the attached images, because I'm not sure how to embed them in the text)
4. References
[1] BetterBatteryStats XDA Edition - http://forum.xda-developers.com/showthread.php?t=1179809
[2] CPU Spy - https://market.android.com/details?id=com.bvalosek.cpuspy
[3] OS Monitor - https://market.android.com/details?id=com.eolwral.osmonitor
[4] Titanium Backup (paid version) - http://matrixrewriter.com/android/
[5] Voltage Control - https://market.android.com/details?id=com.darekxan.voltagecontrol
[6] Android Terminal Emulator by Jack Palevich - https://market.android.com/details?id=jackpal.androidterm
[7] DooMLoRD's Easy Rooting Toolkit [v4.0](zergRush Exploit) - http://forum.xda-developers.com/showthread.php?t=1321582
[8] CF-Root Kernel - http://forum.xda-developers.com/showthread.php?t=788108
[9] RedPillKernel_Rev1.3 - http://forum.xda-developers.com/showthread.php?t=1288850
[10] CheckROM Revolution HD V6 - http://forum.xda-developers.com/showthread.php?t=1312240, http://checkrom.com/
[11] Premium Dark Wallpapers - http://forum.xda-developers.com/showthread.php?t=1474798
[12] Kernel Governors, Modules, I/O Schedulers, CPU Tweaks - http://forum.xda-developers.com/showthread.php?t=1369817
[13] Getting the Most out of the Battery on your Android device - http://softbanksucks.blogspot.com/2011/10/getting-most-out-of-your-battery-on.html
[14] MagicConfig for UV and CPU Governor + I/O Scheduler combinations - http://forum.xda-developers.com/showthread.php?t=1466017
[15] Entropy512 explained CPU idle states - http://forum.xda-developers.com/showpost.php?p=23252902&postcount=17
[16] Android Task Killers Explained - http://lifehacker.com/5650894/andro...ed-what-they-do-and-why-you-shouldnt-use-them
[17] Li-Ion Battery Charge Cycles, Voltages and Storage analysis - http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
[18] IBM/Lenovo recommendations on Li-Ion battery treatment - http://forum.xda-developers.com/showpost.php?p=23258191&postcount=19
5. Disclaimer
Paid apps are mentioned here for clarity. You can of course find an alternative if such exists. Free (no ads) versions of software were listed where possible.
Needless to say that all advice here must be applied only under your own responsibility.
Results at 25h usage: The battery indicator has dropped down to 94%.
However it's a bit hard to predict how much is it going to last this way as long as after initially staying at the value "100%" the indicator decreases a bit faster.
See attached screenshots.
Thanks for the detailed post but i still don't understand why people insist on having a smart phone and then turning off any good feature in it to get 2 days of work out of it.
Agent_Adodas said:
Thanks for the detailed post but i still don't understand why people insist on having a smart phone and then turning off any good feature in it to get 2 days of work out of it.
Click to expand...
Click to collapse
That depends if you dont want xxxx app running every day why run it and why let it connect on a daily basis . Its a Smartphone not a dumbphone that controls the user .Nothing in the Smartphone design says hey guy you are really uncool if you don't have everything turned on .
I turn on what i want when i want but then again i am not sad enough to live my life on facebook .
jje
there's nothing wrong with killing background tasks that eats your battery, but to me it looks funny to turn off WIFI, 3G, Sync or polling.
anyway, that's what i think, other people may think different and will prefer to save on battery life.
Agent_Adodas said:
there's nothing wrong with killing background tasks that eats your battery
Click to expand...
Click to collapse
:facepalm:
http://lifehacker.com/5650894/andro...ed-what-they-do-and-why-you-shouldnt-use-them
Unless you love using terribly coded apps.
This is a Baseline - my initial starting position. Yeah I don't feel cool for running tons of unneeded stuff Actually after 15 hours of uptime I feel pretty bad and a slave of the charger.
I hope to tell more people in a single post what can be optimized, stripping off any superstition, voodoo and some pointless beliefs circulating in the web
I don't say "do like me", but instead what a great hardware SGS2 + core Android software actually seems to be
Please also note I didn't limit myself to 1000MHz, do not recommend reducing voltages etc... the struggle is to put the software in control, not to cripple the experience.
Additionally, I have WiFi at work, at home, at the gym, and between them I'm driving... for that reason I don't need unlimited data. And for new mails I actually get SMS and know when to fetch the mail. If it's important I can turn on the data as well. On business trips abroad there is no unlimited data anyway too - only WiFi at the office and at the hotel. So there are different scenarios...
Serious Observations Bro!
Must say, very clear,simple and awesome way to put together things...will try this out and post again!
Thanks a ton bro! Love the efforts and for helping us out!
Great tips mate... I knew many of them before but i will not use them so much.. I have a feeling that it criples my phone... Limiting my usage of the phone... Instead i have a custom rom,custom kernel ,an extra standard battery,car charger...
I even tryed once to apply most of your tips but they gave me a couple of hours extra batt life. My problem is network signal coverage-edge is fine(but who can surf on egde ?!? ) ,3g and hspda signal is not so good (i travel a lot by car all over my country) and the phone keeps trying to get better network signal and uses more battery...
So most of your tips work if u want to criple your phone and if ur network has great coverage...
Sent from my GT-I9100 using XDA
Using a slow scaling cpu governor defeats the purpose of battery savings. You want something that will scale up fast and scale down just as fast. That way the task gets completed quicker and the cpu can go back to an idle state faster.
Slower governors take longer to complete a task and that uses more battery.
I rather OnDemand complete something in 2 seconds jumping immediately to 1.2Ghz than Conservative in 4 seconds scaling it's way up each step and then scaling back down slowly.
Sent from my GT-I9100 using Tapatalk
Elisha said:
Using a slow scaling cpu governor defeats the purpose of battery savings. You want something that will scale up fast and scale down just as fast. That way the task gets completed quicker and the cpu can go back to an idle state faster.
Slower governors take longer to complete a task and that uses more battery.
I rather OnDemand complete something in 2 seconds jumping immediately to 1.2Ghz than Conservative in 4 seconds scaling it's way up each step and then scaling back down slowly.
Sent from my GT-I9100 using Tapatalk
Click to expand...
Click to collapse
Not true if I'm typing notes. Ondemand will struggle to take me on high frequency, while I'm browsing the texts... Do you need high frequency when reading forums?
Actually I have no problem to play Asphalt 6 and Angry Birds on 1200MHz with this setup
It takes you more cpu cycles to get Asphalt or Angry Birds fully loaded with Conservative than it would with OnDemand.
And you have to remember we have dual-core cpus. It's to your benefit to get both cores scaled up faster to finish the task.
You don't notice this as much because the difference is probably in the milliseconds. But Conservative is more of a power hog than OnDemand.
Sent from my GT-I9100 using Tapatalk
Wow, thats massive and informative! Too good job Sir! Hats Off!
Elisha said:
It takes you more cpu cycles to get Asphalt or Angry Birds fully loaded with Conservative than it would with OnDemand.
And you have to remember we have dual-core cpus. It's to your benefit to get both cores scaled up faster to finish the task.
You don't notice this as much because the difference is probably in the milliseconds. But Conservative is more of a power hog than OnDemand.
Sent from my GT-I9100 using Tapatalk
Click to expand...
Click to collapse
Agree. All that advice is mostly targeted to battery conscious people, this is not a gaming setup There is no one best configuration for all.
It's also not about what exact values to choose, but what approach to take for battery life improvement.
Can't wait to run a UV kernel once the sources drop. That there helps quite a bit to conserve battery.
Sent from my GT-I9100 using Tapatalk
I know pretty much all of this already but it's a useful guide for noobs for sure.
I don't bother anymore with SetCPU or any of that anymore and to be honest it's had little or no impact on battery life which is still excellent.
gingingingin said:
0: IDLE - CPU not clocked
1: AFTR - something not totally clear to me, but an alternative way to IDLE the CPU - ARM Off Top Running with L2 cache keeping its state
2: IDLE+LPA - IDLE + DEEP IDLE - also some parts of hardware are powered down
3: AFTR+LPA - AFTR + DEEP IDLE
Click to expand...
Click to collapse
These are not deep sleep states. Deep sleep is also known as "suspend" - where almost the entire system is shut down.
These are CPU idle states, which allow the core to save power even when the system is "running". They take significantly less time and energy to enter, but save less power. Also, there are only three of them - IDLE, LPA, AFTR. See arch/arm/mach-s5pv310/cpuidle.c in the kernel source for more details.
As an example, with kernels that have the cpuidle backport from the Tab 7 Plus:
IDLE is entered if the CPU is expected to be free for 4 msec (40 msec stock)
AFTR is entered if the CPU is expected to be free for 10 msec (disabled stock)
LPA is entered if the CPU is expected to be free for 40 msec (40 msec stock)
There are some rules that can cause lower states to be entered even if the cpuidle governor chooses LPA or AFTR. (cpuidle governor has nothing to do with cpufreq governor).
Your descriptions of the states are pretty close to what I understand them to be:
IDLE - clock is gated but power remains (does not eliminate any static power consumption)
AFTR - clock is gated, CPU core power removed, cache power remains - this eliminates a great deal of static power consumption - cannot be entered if second core is active
LPA - AFTR + removal of cache power - cannot be entered if second core is active
The above are why 100 MHz is pointless on our device, and in my experience, actually can increase power usage. The achievable voltage difference between 100 MHz and 200 MHz is insignificant for most peope, and if the voltages for two frequencies are the same, it's better to run at the higher frequency and drop into AFTR/LPA to shut off core power more often. The PDF linked from Ezekeel's post at http://forum.xda-developers.com/showthread.php?p=21785924#post21785924 is a useful read on this topic, especially section 6. While it's fairly old, most of the concepts remain valid. For this reason, 500 MHz also doesn't consume much more power than 200 for a given fixed amount of load due to having the same voltage stock as 200 (however, it does increase some internal clocks I believe, leading to slightly increased power) - so when the screen is on I have it set to 500 MHz minimum.
This compares to suspend, aka deep sleep, which takes around 150 msec to enter and 650 msec to resume, and the CPU must be at 800 MHz (or at least have enough voltage to support 800 MHz operation) during this time. Entering suspend/resume is very costly in terms of power due to heavy interrupt load, which is involved in 90% of complaints about high "Android OS" battery usage on Gingerbread. However I believe from some of the testing I've run that improved cpuidle greatly reduces this penalty.
With the improved cpuidle patch, even when I use the Wake Lock app to hold a permanent wakelock for testing purposes, my standby drain is only 1.5%/hour or so. When not holding a wakelock, 0.5%/hour on wifi is easily achievable. It gets much worse at my desk at work, where the signal is weak and the cell radio eats huge amounts of power - there it's around 1%/hour.
Edit: As to task killers - all of the people saying "task killers are worthless" talk about memory management only. The fact is, unfortunately, that there are some crappy apps out there that use too much CPU or hold insanely long wakelocks that you just have to use occasionally. Facebook is still the #1 example here - Facebook is a major battery hog, therefore when you're done with it, you must kill it with fire. However, NEVER use an autokiller and never use it for memory management!
Regarding battery charging, I wonder have you read this article before : batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries (please add http)
The fact seems to be completely opposite from your theory in 2.6.4.
Sent from my GT-I9100 using xda premium
Not sure, the battery article is a bit doubtful. For me at least the testing sequence is strange:
1. Charging current of 1C is a bit high, to say the least. Quick chargers have never been optimal for any type of batteries.
2. Discharge current of 1C is huge and far from being realistic for a mobile phone.
Also if we interpret the results it becomes that at 10% DoD we get 4700 small cycles, which is close to 100% DoD with 500 big cycles... Actually the results are in favor of the 100% DoD.
Of course my interpretation can be wrong, but so far I have got the opposite idea of that.
For practical purposes I can give an example of a Nokia Li-Ion battery thoroughly fully discharged and for 2 years it retained at least 80% capacity. I'd estimate the number of cycles to be 120-150.
On my current laptop the ThinkPad Panasonic battery was always almost completely discharged via settings, attaching screenshots. At 328 cycles and 3.5 years since first use it retains 88% of the design capacity. This is quite a good achievement for a tortured battery I'd say
Note: See the advice/sentence written in the top box by my good old IBM manufacturer (now Lenovo). "... battery deterioration may occur faster if the battery is constantly charged at 100%. Lowering the charge thresholds ... will help increase its lifespan". These guys know their job... I think their sentence almost surely relates to storage though. Storage at 50% is much better than storage at 100% charge. There is room for interpretation again.
Note: This is my second battery on this laptop, the first one Sanyo was a bit worse with the same treatment (maybe older technology) and after 2 years its electronics suddenly failed, while at around 150 cycles.
Entropy512 said:
The above are why 100 MHz is pointless on our device, and in my experience, actually can increase power usage. The achievable voltage difference between 100 MHz and 200 MHz is insignificant for most peope, and if the voltages for two frequencies are the same, it's better to run at the higher frequency and drop into AFTR/LPA to shut off core power more often.
Click to expand...
Click to collapse
First of all, thanks for the detailed explanation of the states.
I remember from the school/uni that the power used is proportional to the frequency. If we have static consumption in the chip it will not be affected by changing the frequency, but the dynamic part of the consumption is essentially doubled when running on 200MHz compared to 100MHz. I don't know the ratio dynamic_consumption:static_consumption for my chip, but it may be around 1:1.
The formulas were something like that: http://forums.anandtech.com/showthread.php?t=119229
Right, so I'm going mad trying to undervolt my CPU.
Sometimes I drop voltages by -50mv, and the phone crashes. Alright I know that the voltage settings have been applied, and it's too low.
On other occasions, I can drop the voltage by ridiculous amounts and have 2.2Ghz running at 600mv (which is obviously impossible), and the phone doesn't crash for two or three days. Obviously the settings aren't being applied.
So my question is, when is the best time to apply voltage settings such that I know they are actually in effect? And is there a way to verify that the voltage settings are actually in effect?
I have been doing a bit more testing.
It seems to me that voltage settings are applied if you apply the setting to all frequency levels (for example some apps like Kernel Tweaker have a -25mv button). Hitting that button twice (for a total of -50mv) causes the phone to crash. However if I were to adjust just the voltage for one frequency at a time, the phone doesn't crash.
Should this be reported to kernel devs? Just want to make sure I'm not doing stuff wrongly.
First of all voltage regulator has some minimum and maximum values, if you go above or bellow those, they will not be applied. If you change voltage just for one frequency, do you force CPU into that particular frequency? Otherwise CPU could be skipping that frequency, for example if you change 600MHz, CPU could be going from 300MHz idle to 0.9GHz skipping some in between values and never actually stay on your changed 600MHz.