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Hi everyone!

I wrote a C++ program for computing the elements of the logistic map and profiled it by using intel VTune Profiler but in the results there is a surprising thing: in the row of 'Cycles of 3+ Port Utilized' there is 55.6 % but below it in every row there is 0.0 %. What does it mean? Where could that 55.6 % disappear? (I'm very beginner in profiling codes.)

The exact program I profiled is here:

```
#include <iostream>
#include <time.h> //clock!!
#include <fstream>
#include <vector>
#include <stdio.h>
#define MAX_VECTOR_SIZE 256
#include <vectorclass.h>
#include <cstdlib>
#include <malloc.h>
using namespace std;
int main()
{
// Allocated on STACK
const int Resolution = 4 * 8 * 3125; // Dividable by 4
const int Transients = 512;
const int SavedPoints = 128;
const int LoopUnrollFactor = 4 * 8;
//double r[Resolution];
//double x[Resolution];
// Allocated on HEAP
double* r = (double*)_aligned_malloc(Resolution * sizeof(double),64);
double* x = (double*)_aligned_malloc(Resolution * sizeof(double),64);
//double* r = new double[Resolution];
//double* x = new double[Resolution];
// Initialisation
double dr = 4.0 / (Resolution - 1.0); // Only 1 type conversion!
r[0] = 0.0;
x[0] = 0.5;
for (int i = 1; i < Resolution; i++)
{
r[i] = r[i - 1] + dr;
x[i] = 0.5;
}
// Transient iterations
clock_t SimulationStart = clock();
Vec4d xact[8];
Vec4d ract[8];
for (int i = 0; i < Resolution; i += LoopUnrollFactor)
{
#pragma unroll
for (int k = 0; k < 8; k++)
{
xact[k].load_a(x + i + k * 4); // Loading states from alligned memory
ract[k].load_a(r + i + k * 4); // Loading parameters from alligned memory
}
for (int j = 0; j < Transients; j++)
{
#pragma unroll
for (int k = 0; k < 8; k++)
xact[k] = ract[k] * xact[k] * (1.0 - xact[k]);
}
#pragma unroll
for (int k = 0; k < 8; k++)
{
xact[k].store_a(x + i + k * 4); // Storing states from alligned memory
ract[k].store_a(r + i + k * 4); // Storing parameters from alligned memory
}
}
clock_t SimulationEnd = clock();
cout << "Simulation time: " << 1000.0*(SimulationEnd - SimulationStart) / CLOCKS_PER_SEC << "ms" << endl << endl;
// Converged iterations and save to file
/*ofstream DataFile;
DataFile.open("LogisticMap.txt");
int Width = 18;
DataFile.precision(10);
DataFile.flags(ios::scientific);
for (int i = 0; i < Resolution; i++)
{
for (int j = 0; j < SavedPoints; j++)
{
x[i] = r[i] * x[i] * (1.0 - x[i]);
DataFile.width(Width); DataFile << r[i]; //Don't place here any commas, because dlmread won't work in MATLAB!!!
DataFile.width(Width); DataFile << x[i];
DataFile << '\n';
}
}
DataFile.close();*/
return 0;
}
```

Thanks for your answer in advance.

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Hi.

Is it possible to increase workload time

0.038 sec is too small to build correct microarchitecture metrics at all.

They could be incorrect such in your case

Kirill

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Hi,

Thanks for posting in Intel forums.

We will try from our end and let you know.

Regards,

Janani Chandran

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Hi.

Is it possible to increase workload time

0.038 sec is too small to build correct microarchitecture metrics at all.

They could be incorrect such in your case

Kirill

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Hi,

Is your issue resolved? Please let us know if the issue still persists.

Regards,

Janani Chandran

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Hi!

Thank you, it helped a lot! After increasing the number of Resolution the error did'nt appear.

mrkf100

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Hi,

Thanks for the confirmation. If you need any additional information, please submit a new question as this thread will no longer be monitored.

Regards,

Janani Chandran

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