android cpu 利用率

proc/$PID/stat文件中的值  

其内容14~17 列  ：

       seq_put_decimal_ull(m, ' ', cputime_to_clock_t(utime));

        seq_put_decimal_ull(m, ' ', cputime_to_clock_t(stime));

        seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cutime));

        seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cstime));

的四位数字分别是:

utime该任务在用户运行状态的时间

stime该任务在核心运行的时间

cutime全部已死线程在用户状态运行状态的时间

cstime全部已死线程在核心的运行时间

因此processCpuTime为这个四个属性的和.

当前进行所占CPU的算法是:

100*(processCpuTimeS-processCpuTimeF)/(totalCpuTimeS-totalCpuTimeF)

 

 

内存：

http://blog.csdn.net/jackjones_008/article/details/41944973

http://www.cnblogs.com/adv-qbj/p/4719787.html

http://gityuan.com/2016/01/02/memory-analysis-command/

1. Active = Active(anon) + Active(file) Inactive = Inactive(anon) + Inactive(file)
2. Active(file), Inactive(file) has file back-end which means its original file is in disk but to use it faster it was loaded on RAM.
3. Active(file) + Inactive(file) + Shmem = Cached + Buffer + SwapCached