Odtnhj

I've run into a problem that appears to effect only dual-core Android devices running gingerbread or greater. I'd like to give a dialog regarding this issue only to my users that fit that criteria. 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?

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.

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).

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

This is pretty simple.

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

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

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()
 )