Android 中获取当前 CPU 频率和占用率

最近在优化 App 的性能，需要获取当前 CPU视频频率和占用率，通过查询资料，大致思路如下：

目前没有标准的 API 来获取 CPU 的使用频率，只能通过读取指定 CPU 文件获取当前 CPU 频率，在某些机器或者特定版本中，可能需要ROOT 权限或者特殊权限，因此会存在一定几率的失败，因此需要做好 Try...catch 动作。又因为现在手机 CPU 的多核数目，因此我们可能需要获取多个 CPU 频率数，并取平均值。

获取系统 CPU 核心数：

kotlin 复制代码

 val cpuCoreNum = Runtime.getRuntime().availableProcessors()

获取指定 CPU 当前频率：

kotlin 复制代码

/sys/devices/system/cpu/cpu${index}/cpufreq/scaling_cur_freq

那么核心代码为：

kotlin 复制代码

private fun getAllCpuCoreFrequency() : Long {

        var frequency = 0L

        for (index in 0 until  cpuCoreNum){
            frequency += readFile("/sys/devices/system/cpu/cpu$index/cpufreq/scaling_cur_freq")
        }

        BLog.d("frequency : $frequency")

        return frequency / cpuCoreNum
    }


  private fun readFile(filePath: String): Long{
        try {
            val file = RandomAccessFile(filePath, "r")
            val content = file.readLine()
            file.close()

            if (TextUtils.isEmpty(content)){
                return 0L
            }

            BLog.d("readFile content : $content")

            return content.trim().toLong()

        }catch (e : Exception){
            e.printStackTrace()

           return 0L
        }
    }

如果需要获取 CPU 的占用率，那么就需要知道每个核心的最大频率和最小频率，同样是通过文件获取：

kotlin 复制代码

//max frequency file
/sys/devices/system/cpu/cpu${index}/cpufreq/cpuinfo_max_freq

//min frequency file
/sys/devices/system/cpu/cpu${index}/cpufreq/cpuinfo_min_freq

那么核心代码为：

kotlin 复制代码

object CPUUtils {

    private var cpuCoreNum = 0
    private var cpuMaxFrequency = 0L
    private var cpuMinFrequency = 0L

    fun initCpuCoreNum(){
        if (cpuCoreNum <= 0 || cpuMaxFrequency <= 0L || cpuMinFrequency <= 0L){

            cpuCoreNum = Runtime.getRuntime().availableProcessors()
            initMaxAndMinFrequency()

            if (cpuCoreNum > 0 && cpuMaxFrequency > 0L && cpuMinFrequency > 0L){
               SpManager.getInstance().setCanUseCPUFrequency(true)
            }
        }

        BLog.d("cpuCoreNum : $cpuCoreNum")
    }

    private fun initMaxAndMinFrequency()  {
        if (cpuCoreNum <= 0){
            return
        }

        cpuMaxFrequency = 0L
        cpuMinFrequency = 0L

        for (index in 0 until cpuCoreNum){
            cpuMaxFrequency += readFile("/sys/devices/system/cpu/cpu${index}/cpufreq/cpuinfo_max_freq")
            cpuMinFrequency += readFile("/sys/devices/system/cpu/cpu${index}/cpufreq/cpuinfo_min_freq")
        }


        BLog.d("cpuMaxFrequency : $cpuMaxFrequency, cpuMinFrequency : $cpuMinFrequency")
    }


    private fun readFile(filePath: String): Long{
        try {
            val file = RandomAccessFile(filePath, "r")
            val content = file.readLine()
            file.close()

            if (TextUtils.isEmpty(content)){
                return 0L
            }

            BLog.d("readFile content : $content")

            return content.trim().toLong()

        }catch (e : Exception){
           ExceptionHandler.recordException(e)

           return 0L
        }
    }
    
    private fun getAllCpuCoreFrequency() : Long {
        initCpuCoreNum()

        if (cpuCoreNum <=0){
            return 0L
        }

        var frequency = 0L

        for (index in 0 until  cpuCoreNum){
            frequency += readFile("/sys/devices/system/cpu/cpu$index/cpufreq/scaling_cur_freq")
        }

        BLog.d("frequency : $frequency")

        return frequency
    }

    fun findCurrentFrequencyPercent() : Long {

        val currentFrequency = getAllCpuCoreFrequency()

        BLog.d("currentFrequency : $currentFrequency, cpuMinFrequency : $cpuMinFrequency, cpuMaxFrequency : $cpuMaxFrequency")

        if (cpuMaxFrequency - cpuMinFrequency <= 0L || currentFrequency - cpuMinFrequency < 0L || cpuMaxFrequency - currentFrequency < 0L){
            return 0L
        }

        return (currentFrequency - cpuMinFrequency) * 100 / (cpuMaxFrequency - cpuMinFrequency)
    }


    fun getCpuCoreFrequency() : Long {
        initCpuCoreNum()

        if (cpuCoreNum <=0){
            return 0L
        }

        return getAllCpuCoreFrequency() / cpuCoreNum
    }

}

获取 CPU 频率：

kotlin 复制代码

CPUUtils.getCpuCoreFrequency()

获取 CPU 占用率：

kotlin 复制代码

CPUtils.findCurrentFrequencyPercent()