changing scaling_governor on android device

hi guys im trying to change the scaling_governor on android device using this code

String[] args = {"/system/bin/echo us开发者_运维技巧erspace >", "/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor"};
ProcessBuilder cmd1;  
cmd1 = new ProcessBuilder(args);

Process process = cmd1.start();

but nothing has changed :( what am i doing wrong??

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Is your program running as root (euid == 0)?

The scaling governor is restricted to writing by only root:

-rw-r--r-- 1 root root 4096 2011-01-30 13:45 /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor