c++ - 对某些Unix代码有疑问吗？

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#include <mach/mach_init.h>
#include <mach/mach_error.h>
#include <mach/mach_host.h>
#include <mach/vm_map.h>

static unsigned long long _previousTotalTicks = 0;
static unsigned long long _previousIdleTicks = 0;

// Returns 1.0f for "CPU fully pinned", 0.0f for "CPU idle", or somewhere in between
// You'll need to call this at regular intervals, since it measures the load between
// the previous call and the current one.
float GetCPULoad()
{
    host_cpu_load_info_data_t cpuinfo;
    mach_msg_type_number_t count = HOST_CPU_LOAD_INFO_COUNT;
    if (host_statistics(mach_host_self(), HOST_CPU_LOAD_INFO, (host_info_t)&cpuinfo, &count) == KERN_SUCCESS)
    {
        unsigned long long totalTicks = 0;
        for(int i=0; i<CPU_STATE_MAX; i++) totalTicks += cpuinfo.cpu_ticks[i];
        sysLoadPercentage = CalculateCPULoad(cpuinfo.cpu_ticks[CPU_STATE_IDLE], totalTicks);
    }
    else return -1.0f;
}

float CalculateCPULoad(unsigned long long idleTicks, unsigned long long totalTicks)
{
   unsigned long long totalTicksSinceLastTime = totalTicks-_previousTotalTicks;
   unsigned long long idleTicksSinceLastTime  = idleTicks-_previousIdleTicks;
   float ret = 1.0f-((totalTicksSinceLastTime > 0) ? ((float)idleTicksSinceLastTime)/totalTicksSinceLastTime : 0);
   _previousTotalTicks = totalTicks;
   _previousIdleTicks  = idleTicks;
   return ret;
}

我对我希望您能提供帮助的代码有一些疑问：


什么是“ host_cpu_load_info_data_t”结构？这有什么用途？
什么是“ mach_msg_type_number_t”结构？这有什么用途？
预处理程序定义“ HOST_CPU_LOAD_INFO_COUNT”及其用途是什么？
什么是host_statistics函数？
上面列出的host_statistics函数的每个参数是什么意思？ （从未见过他们）
什么是预处理器定义CPU_STATE_MAX和CPU_STATE_IDLE？
预处理程序定义KERN_SUCCESS是什么？


如果无法回答，请将我引到包含所有这些答案的站点。我已经尝试过谷歌搜索，但是找不到任何答案，也找不到任何文档。另外，如果问题过于具体，我将删除该问题，但请在这样的问题仍然有效的地方提供一个来源。

谢谢

最佳答案

包含“所有这些答案”的站点是http://www.opensource.apple.com/source/xnu/xnu-1699.24.8/。您可能还会发现Mac OS X Internals一书（由Amit Singh撰写）很有用。

关于c++ - 对某些Unix代码有疑问吗？ ，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/8767504/