CODEWITHSUNDEEP
android
newbyca
newbyca

Reputation: 1513

How can you detect a dual-core cpu on an Android device from code?

I've run into a problem that appears to affect only dual-core Android devices running Android 2.3 (Gingerbread or greater). I'd like to give a dialog regarding this issue, but only to my users that fit that criterion. I know how to check OS level but haven't found anything that can definitively tell me the device is using multi-core.

Any ideas?

Upvotes: 23

Views: 22613

Answers (6)

android developer
android developer

Reputation: 116060

Here's my solution, in Kotlin, based on this one:

/**
 * return the number of cores of the device.<br></br>
 * based on : http://stackoverflow.com/a/10377934/878126
 */
val coresCount: Int by lazy {
    return@lazy kotlin.runCatching {
        val dir = File("/sys/devices/system/cpu/")
        val files = dir.listFiles { pathname -> Pattern.matches("cpu[0-9]+", pathname.name) }
        max(1, files?.size ?: 1)
    }.getOrDefault(1)
}

Upvotes: 1

G00fY
G00fY

Reputation: 5347

I use a combination of both available solutions:

fun getCPUCoreNum(): Int {
  val pattern = Pattern.compile("cpu[0-9]+")
  return Math.max(
    File("/sys/devices/system/cpu/")
      .walk()
      .maxDepth(1)
      .count { pattern.matcher(it.name).matches() },
    Runtime.getRuntime().availableProcessors()
  )
}

Upvotes: 1

David
David

Reputation: 1718

Unfortunately for most Android devices, the availableProcessors() method doesn't work correctly. Even /proc/stat doesn't always show the correct number of CPUs.

The only reliable method I've found to determine the number of CPUs is to enumerate the list of virtual CPUs at /sys/devices/system/cpu/ as described in this forum post. The code:

/**
 * Gets the number of cores available in this device, across all processors.
 * Requires: Ability to peruse the filesystem at "/sys/devices/system/cpu"
 * @return The number of cores, or 1 if failed to get result
 */
private int getNumCores() {
    //Private Class to display only CPU devices in the directory listing
    class CpuFilter implements FileFilter {
        @Override
        public boolean accept(File pathname) {
            //Check if filename is "cpu", followed by one or more digits
            if(Pattern.matches("cpu[0-9]+", pathname.getName())) {
                return true;
            }
            return false;
        }      
    }

    try {
        //Get directory containing CPU info
        File dir = new File("/sys/devices/system/cpu/");
        //Filter to only list the devices we care about
        File[] files = dir.listFiles(new CpuFilter());
        //Return the number of cores (virtual CPU devices)
        return files.length;
    } catch(Exception e) {
        //Default to return 1 core
        return 1;
    }
}

This Java code should work in any Android application, even without root.

Upvotes: 47

DanKodi
DanKodi

Reputation: 3640

This is pretty simple.

int numberOfProcessors = Runtime.getRuntime().availableProcessors();

Typically it would return 1 or 2. 2 would be in a dual-core CPU.

Upvotes: 4

Thai Phi
Thai Phi

Reputation: 81

If you're working with a native application, you should try this:

#include <unistd.h>
int GetNumberOfProcessor()
{
    return sysconf(_SC_NPROCESSORS_CONF);
}

It work on my i9100 (which availableProcessors() returned 1).

Upvotes: 8

A.J.
A.J.

Reputation: 1047

You can try using Runtime.availableProcessors() as is suggested in this answer

Is there any API that tells whether an Android device is dual-core or not?

---edit---

A more detailed description is given at Oracle's site

availableProcessors

public int availableProcessors()

Returns the number of processors available to the Java virtual machine.

This value may change during a particular invocation of the virtual machine. Applications that are sensitive to the number of available processors should therefore occasionally poll this property and adjust their resource usage appropriately.

Returns:

the maximum number of processors available to the virtual machine; never smaller than one

Since:

  1.4

Upvotes: 4

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