/// <summary>Stops counting the processor cycles, releases the system resources associated with the cycle counter, and returns the number of cycles elapsed.</summary>
/// <param name="cycleCounter">An object representing the state of the cycle counter returned by <see cref="AcquireCycleCounter()" />. The cycle counter should be released only once, and this function invalidates the state object.</param>
/// <returns>The number of cycles elapsed since the call to <see cref="AcquireCycleCounter()" />.</returns>
/// <exception cref="System.InvalidOperationException">The cycleCounter object is not a valid state of the cycle counter. This can happen if the cycleCounter object was released previously.</exception>
/// <exception cref="System.PlatformNotSupportedException">The processor does not have a cycle counter or the operating system does not provide access to the CPU cycle counter</exception>
/// <exception cref="System.SystemException">If the attempt to read the cycle counter or release the OS resources failed inside the OS kernel.</exception>
/// <seealso cref="AcquireCycleCounter()" />
public static ulong ReleaseCycleCounter(CpuCycleCounterState cycleCounter)
{
ulong ticks;
Status status = yepLibrary_GetCpuCyclesRelease(ref cycleCounter.state, out ticks);
if (status != Status.Ok)
{
throw GetException(status);
}
return(ticks);
}
public static void Main(string[] args)
{
const int arraySize = 1024 * 4;
const int iterationMax = 1000;
short[] array = new short[arraySize];
/* Check if the system supports performance counters */
if (Yeppp.Library.IsSupported(Yeppp.CpuSystemFeature.CycleCounter))
{
/* Estimate the measurement overhead */
ulong minOverhead = UInt64.MaxValue;
/* Repeat many times and take the minimum to filter out noise from interrupts and caches/branch prediction/page faults */
for (int iteration = 0; iteration < iterationMax; iteration++)
{
Yeppp.CpuCycleCounterState state = Yeppp.Library.AcquireCycleCounter();
ulong cycles = Yeppp.Library.ReleaseCycleCounter(state);
minOverhead = Math.Min(minOverhead, cycles);
}
/* Now measure the cycles for computation */
ulong minCycles = UInt64.MaxValue;
/* Repeat many times and take the minimum to filter out noise from interrupts and caches/branch prediction/page faults */
for (int iteration = 0; iteration < iterationMax; iteration++)
{
Yeppp.CpuCycleCounterState state = Yeppp.Library.AcquireCycleCounter();
Random rng = new Random();
for (int i = 0; i < arraySize; i++)
{
array[i] = (short)rng.Next();
}
ulong cycles = Yeppp.Library.ReleaseCycleCounter(state);
minCycles = Math.Min(minCycles, cycles);
}
/* Subtract the overhead and normalize by the number of elements */
double cpe = ((double)(minCycles - minOverhead)) / ((double)arraySize);
Console.WriteLine("Cycles per element: {0:F2}", cpe);
}
else
{
Console.WriteLine("Processor cycle counter is not supported");
}
}
/// <summary>Stops counting the processor cycles, releases the system resources associated with the cycle counter, and returns the number of cycles elapsed.</summary>
/// <param name="cycleCounter">An object representing the state of the cycle counter returned by <see cref="AcquireCycleCounter()" />. The cycle counter should be released only once, and this function invalidates the state object.</param>
/// <returns>The number of cycles elapsed since the call to <see cref="AcquireCycleCounter()" />.</returns>
/// <exception cref="System.InvalidOperationException">The cycleCounter object is not a valid state of the cycle counter. This can happen if the cycleCounter object was released previously.</exception>
/// <exception cref="System.PlatformNotSupportedException">The processor does not have a cycle counter or the operating system does not provide access to the CPU cycle counter</exception>
/// <exception cref="System.SystemException">If the attempt to read the cycle counter or release the OS resources failed inside the OS kernel.</exception>
/// <seealso cref="AcquireCycleCounter()" />
public static ulong ReleaseCycleCounter(CpuCycleCounterState cycleCounter) {
ulong ticks;
Status status = yepLibrary_GetCpuCyclesRelease(ref cycleCounter.state, out ticks);
if (status != Status.Ok)
throw GetException(status);
return ticks;
}