CODEWITHSUNDEEP
androidcpu-cores
user1974977
user1974977

Reputation: 53

Android count how many cpus are online?

How would i go about determining how many cpu's are online? I have a handler running every 1000 ms reading the current frequency and i also want to determine how many cores are online.

I've been looking through the directory "/sys/devices/system/cpu/". I've monitored "/sys/devices/system/cpu/cpu1/online" which is always 1, i've monitored /cpu0/online which is also always 1.

Is this information kernel/device specific? How can i find how many cores are online in a way that works on all devices?

edit: Runtime.availableProcessors() seems to work nicely, i'm still interested in knowing if there is a system file that tells you if a core is on/off?

Upvotes: 1

Views: 490

Answers (2)

hakki
hakki

Reputation: 6517

 /**
 * 
 * @return integer Array with 4 elements: user, system, idle and other cpu
 * usage in percentage. You can handle from here what you want. 
 * For example if you only want active CPUs add simple if statement >0 for usage
 */

private int[] getCpuUsageStatistic() {

String tempString = executeTop();

tempString = tempString.replaceAll(",", "");
tempString = tempString.replaceAll("User", "");
tempString = tempString.replaceAll("System", "");
tempString = tempString.replaceAll("IOW", "");
tempString = tempString.replaceAll("IRQ", "");
tempString = tempString.replaceAll("%", "");
for (int i = 0; i < 10; i++) {
    tempString = tempString.replaceAll("  ", " ");
}
tempString = tempString.trim();
String[] myString = tempString.split(" ");
int[] cpuUsageAsInt = new int[myString.length];
for (int i = 0; i < myString.length; i++) {
    myString[i] = myString[i].trim();
    cpuUsageAsInt[i] = Integer.parseInt(myString[i]);
}
return cpuUsageAsInt;
}

private String executeTop() {
java.lang.Process p = null;
BufferedReader in = null;
String returnString = null;
try {
    p = Runtime.getRuntime().exec("top -n 1");
    in = new BufferedReader(new InputStreamReader(p.getInputStream()));
    while (returnString == null || returnString.contentEquals("")) {
        returnString = in.readLine();
    }
} catch (IOException e) {
    Log.e("executeTop", "error in getting first line of top");
    e.printStackTrace();
} finally {
    try {
        in.close();
        p.destroy();
    } catch (IOException e) {
        Log.e("executeTop",
                "error in closing and destroying top process");
        e.printStackTrace();
    }
}
return returnString;
}

Upvotes: -1

Kristian Evensen
Kristian Evensen

Reputation: 1345

I have success with availableProcessors() on the devices I have tried. A more detailed description of the function is available in the official Java doc. Another possible solution is described in this forum post.

Upvotes: 1

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