Retrieve system uptime using C#

Is there a simple way to get a system's uptime using C#?

Solution 1:

public TimeSpan UpTime {
    get {
        using (var uptime = new PerformanceCounter("System", "System Up Time")) {
            uptime.NextValue();       //Call this an extra time before reading its value
            return TimeSpan.FromSeconds(uptime.NextValue());
        }
    }
}

Solution 2:

I'm a bit late, but another simple way is to use the GetTickCount64 function, which is available starting with Windows Vista and does not overflow as GetTickCount does:

public static TimeSpan GetUpTime()
{
    return TimeSpan.FromMilliseconds(GetTickCount64());
}

[DllImport("kernel32")]
extern static UInt64 GetTickCount64();

Solution 3:

System.Environment.TickCount gets the number of milliseconds since the system was restarted.

Beware though that it is an Int32 and will overflow after 24.9 days and will become negative. See the remarks on the MDSN docs.

Solution 4:

My machine has an uptime of 58 days 17 hours according to Task Manager. I went through and tried each answer here and the fast ones are off by a little bit (~1-3 minutes roughly, but over 58 days of uptime):

Stopwatch.GetTimeStamp():                   58days 17hours 11minutes 25seconds
~Time to calculate (ms): 6.8413
DllImport GetTickCount64():                 58days 17hours 13minutes 34seconds
~Time to calculate (ms): 0.2192
PerformanceCounter(System, System Up Time): 58days 17hours 14minutes 02seconds
~Time to calculate (ms): 1233.2854
ManagementObject LastBootUpTime:            58days 17hours 14minutes 02seconds
~Time to calculate (ms): 30.0283

The last two, using PerformanceCounter or using ManagementObject, are always within the same second as Windows Task Manager (just have to take my word for it, or try it yourself with the code below). Based on the results I am going to use the ManagementObject LastBootUpTime method because it's drastically faster than the PerformanceCounter but is still perfectly accurate when compared to Task Manager.

Note that I did subtract the current elapsed time from each method before printing the times, but the whole thing takes less than 2 seconds to run so the time shift can't be explained by improperly accounting for execution time anyway. Here's the code I used:

[System.Runtime.InteropServices.DllImport("kernel32")]
extern static UInt64 GetTickCount64();

public static void Main()
{
    var start = Stopwatch.StartNew();

    var eachStart = Stopwatch.StartNew();
    var ticks = Stopwatch.GetTimestamp();
    var uptime = ((double)ticks) / Stopwatch.Frequency;
    var uptimeTimeSpan = TimeSpan.FromSeconds(uptime);
    Console.WriteLine("Stopwatch.GetTimeStamp():                   " + uptimeTimeSpan.Subtract(start.Elapsed).ToString(@"dd\d\a\y\s\ hh\h\o\u\r\s\ mm\m\i\n\u\t\e\s\ ss\s\e\c\o\n\d\s"));
    Console.WriteLine($"~Time to calculate (ms): {eachStart.Elapsed.TotalMilliseconds}");

    eachStart.Restart();
    Console.WriteLine("DllImport GetTickCount64():                 " + TimeSpan.FromMilliseconds(GetTickCount64()).Subtract(start.Elapsed).ToString(@"dd\d\a\y\s\ hh\h\o\u\r\s\ mm\m\i\n\u\t\e\s\ ss\s\e\c\o\n\d\s"));
    Console.WriteLine($"~Time to calculate (ms): {eachStart.Elapsed.TotalMilliseconds}");

    eachStart.Restart();
    var upTime = new PerformanceCounter("System", "System Up Time");
    upTime.NextValue();       //Call this an extra time before reading its value
    Console.WriteLine("PerformanceCounter(System, System Up Time): " + TimeSpan.FromSeconds(upTime.NextValue()).Subtract(start.Elapsed).ToString(@"dd\d\a\y\s\ hh\h\o\u\r\s\ mm\m\i\n\u\t\e\s\ ss\s\e\c\o\n\d\s"));
    Console.WriteLine($"~Time to calculate (ms): {eachStart.Elapsed.TotalMilliseconds}");

    eachStart.Restart();
    ManagementObject mo = new ManagementObject(@"\\.\root\cimv2:Win32_OperatingSystem=@");
    DateTime lastBootUp = ManagementDateTimeConverter.ToDateTime(mo["LastBootUpTime"].ToString());
    Console.WriteLine("ManagementObject LastBootUpTime:            " + (DateTime.Now.ToUniversalTime() - lastBootUp.ToUniversalTime()).Subtract(start.Elapsed).ToString(@"dd\d\a\y\s\ hh\h\o\u\r\s\ mm\m\i\n\u\t\e\s\ ss\s\e\c\o\n\d\s"));
    Console.WriteLine($"~Time to calculate (ms): {eachStart.Elapsed.TotalMilliseconds}");
}

Solution 5:

Precise and bigger than System.Environment.TickCount, not involving OS horrific perf counters, WMI or native calls:

var ticks = Stopwatch.GetTimestamp();
var uptime = ((double)ticks) / Stopwatch.Frequency;
var uptimeSpan = TimeSpan.FromSeconds(uptime);