android how to force cpu core offline(shut down cores)

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I'm using a quad-core smartphone.

I want to know how to force three cores or two cores offline. Thus I can measure the performance of different active core counts at different frequency level running a specified benchmark.

I can manage the core frequency through "userspace governor". However, I can't shut down cores. When I run benchmarks, the idle cores will wake up.

I've connect to the phone using "adb shell". I can get the root access either.

Could anyone help to solve this problem? Thanks in advance.

run following commands to turn off cpu1, cpu2, cpu3.

adb root
adb stop mpdecision
adb shell
echo "0" > /sys/devices/system/cpu/cpu1/online
echo "0" > /sys/devices/system/cpu/cpu2/online
echo "0" > /sys/devices/system/cpu/cpu3/online

How to turn on cpu cores on my Android, If your phone shows that some of your Processor's Cores are not being utilized, that Does Android often shut down apps in order to manage CPU and RAM? my PC (Before starting to work on it)? My CPU is Intel Core 2 duo with 4GB RAM. Linux (the OS behind Android) uses what's called a "governor" to turn CPU cores on and off as needed. If Android doesn't have a task that needs a separate core, that core remains off to save power. Here's a screen shot of the CPU in my tablet. One core of 8 running, and at only 299 MHz! That's part of how Android achieves week+ standby time.

"stop mpdecision" must be run after "adb shell", and without "adb" written before it.

So the commands (on PC) should be:

adb shell
su
stop mpdecision
echo "0" > /sys/devices/system/cpu/cpu1/online
echo "0" > /sys/devices/system/cpu/cpu2/online
echo "0" > /sys/devices/system/cpu/cpu3/online

[APP] CoreDisabler v.1.0 (DISABLE CPU CORES …, Not sure why someone buys a powerful quad core phone and then disabled cores and also under clocks it. I mean if battery life is your main  I was recently asked how to turn off a CPU core in a dual-core computer. Depending on your need, there are actually 3 ways to accomplish it. The first method disables cores for the whole system. The second turns them off for a specific program. Finally, you may just want to shut off those fake Hyperthreading cores.

You can force "online" status by changing permissions for the corresponding file:

# Without stopping this service, the following approach will fail
# You can run it after. This will increase battery life. So, I suggest to run it.
stop mpdecision

# Make the file writable
chmod 664 /sys/devices/system/cpu/cpu0/online

# Make the core always offline
echo 0 > /sys/devices/system/cpu/cpu0/online

# Make the file read-only. 
# Now "online" status will not be changed by external apps
chmod 444 /sys/devices/system/cpu/cpu0/online

# Run the service again
start mpdecision

You have to run all that stuff for every cpu core. I'd suggest to create a bash script, like that:

...
set_core_offline () {
    local core=$1
    chmod 664 /sys/devices/system/cpu/cpu$core/online
    echo 0 > /sys/devices/system/cpu/cpu$core/online
    chmod 444 /sys/devices/system/cpu/cpu$core/online
}

# Works for 4-core CPUs
set_cores_offline () {
    set_core_offline 0
    set_core_offline 1
    set_core_offline 2
    set_core_offline 3
}
...

And, of course, this solution is not perfect. Look again, at the code snippet:

echo 0 > /sys/devices/system/cpu/cpu0/online
chmod 444 /sys/devices/system/cpu/cpu0/online

These are two separate commands. After execution of the first one, an external app might change "online" status to "1" again. After that the second command will fix this status as unchangeable. So, the clearest solution would be to wrap these 2 commands into a loop and check the status until we'd get desired results.

Why is Android disabling cores? : AndroidQuestions, He mentioned that they were always reading "Offline". Two cores offline. and compiling multi-core applications in an ARM64 environment (debugging stuff). I got a lot of answers regarding CPU throttling done by the kernel, but I said in my Is there any way to disable the annoying snap-to-edge behavior while  Samsung has confirmed that it has shut down its custom CPU unit in Austin, Texas. This suggests that the company will stick to Arm designs in the future.

How to turn off CPU cores on Samsung Galaxy A8?, Q: How do i logically offline a CPU? A: Do the following. #echo 0 > /sys/devices/​system/cpu/cpuX/online. Once the logical  At first both cpus are online and if I hit times in system tuner it shows times for both cpus. After awhile the 2nd core will go offline and system tuner only shows one cpu in times. I also set system tuner to force cpus online on reboot so if I reboot both cores are back online.

CPU-Z shows 8 cores, but 4 of them are stopped, Why would 8 cores be active if you are in cpu-z app. Four cores down vote. Actually the core usage depends on the usage of particular apps. Here is simple tutorial how to save energy , and shut down your cores. Here is simple tutorial how to save energy , and shut down your cores. How to shut down CPU cores tutorial

disable cores android, adb - android how to force cpu core offline(shut down Donald Hernandez|23 days ago. 10/18/2018 · I want to know how to force three cores or two cores  Fact or Fiction: Android apps only use one CPU core. We have had multi-core processors in our PCs for over a decade, and today they are considered the norm. At first it was dual-core, then quad-core, and today companies like Intel and AMD offer high end desktop processors with 6 or even 8 cores.

Comments
  • I'm not sure this is possible. You can set the cores to very low frequency, but I think shutting them "off" would be a security concern.
  • These commands do not work all the time. Right after writing 0 into online, it becomes 1 again.
  • if mpdecision is still running , i can imagine this happening.
  • "mpdecision" is a cpu schedule mechanism for Qualcomm only.