Android如何获取当前CPU频率和占用率_Android

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：

 val cpucorenum = runtime.getruntime().availableprocessors()

获取指定 cpu 当前频率：

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

那么核心代码为：

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：

//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：

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：