c# cpu使用率查询

private void button1_Click(object sender, EventArgs e){    selectedServer = "JS000943";    listBox1.Items.Add(GetProcessorIdleTime(selectedServer).ToString());}private static int GetProcessorIdleTime(string selectedServer){    try    {        var searcher =           ManagementObjectSearcher             (@"\\"+ selectedServer +@"\root\CIMV2",              "SELECT * FROM Win32_PerfFormattedData_PerfOS_Processor WHERE Name=\"_Total\"");        ManagementObjectCollection collection = searcher.Get();        ManagementObject queryObj = collection.Cast<ManagementObject>().First();        return Convert.ToInt32(queryObj["PercentIdleTime"]);    }    catch (ManagementException e)    {        MessageBox.Show("An error occurred while querying for WMI data: " + e.Message);    }    return -1;}