How to read cpu frequency on android device [closed]

Question

Is there any Java API for that? How can I read this information.

Beagle

Answer 1

To have frequency on Android, just read these special files in /sys directory:

#cat "/sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq"
#cat "/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq"
#cat "/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq"

You will have current, min and max Frequency allowed.

Zenobia

Awesome answer Ellis, you really helped me a lot. One thing that I found in investigating this was that scaling_cur_freq is not necessarily the current CPU frequency, but rather what the kernel thinks the frequency is. To get the real frequency, you need root access to read cpuinfo_cur_freq. Also, gaining root access allows you to set the cpu speed, which is quite useful for profiling under best/worst case conditions. – Hood

Hummm It seems to me that even with root access you can't edit the cpuinfo_* files.. – Uruguay

How can we get CPU load or utilization? – Build

How can these files be read from within an app? – Lashelllasher

I notice subdirectory policyX under /sys/devices/system/cpu/cpufreq/, what is that? – Jablonski

Answer 2

not MHz, but at least something. bogoMIPS value can be useful for you.

private String ReadCPUinfo()
 {
  ProcessBuilder cmd;
  String result="";

  try{
   String[] args = {"/system/bin/cat", "/proc/cpuinfo"};
   cmd = new ProcessBuilder(args);

   Process process = cmd.start();
   InputStream in = process.getInputStream();
   byte[] re = new byte[1024];
   while(in.read(re) != -1){
    System.out.println(new String(re));
    result = result + new String(re);
   }
   in.close();
  } catch(IOException ex){
   ex.printStackTrace();
  }
  return result;
 }

Darendaresay

Thanks, but is there any way to convert it to MHz or read it somewhere? – Beagle

Any reason you're not just opening /proc/cpuinfo as a file and reading it directly? – Saponify

michael, read a wiki page about bogoMIPS, there's a formula. fadden, I'm not sure that file could be simply read from java, just found this code laying around. – Darendaresay

Answer 3

If you are interested in how long your system spent in what state, check out the file

/sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state

I'm not sure, whether root access is necessary for that.

Falsework

Root access seems not to be neccesary, unlike for cpuinfo_cur_freq. – Nafis