How to properly evaluate speed when charater follows path constrain?

Hi. Currently my character sliding along the curve like on ice. I went to the path curve panel where is two options - frames and evaluation time. I set frames to the same number that my composition has. But it didnt work - still like on ice. So i tried to animate evaluation - but i dont know which values to enter to make my character go along the path at the speed which will be equal to the lenght of the curve. Please if you know give me example how to do it properly. Thanks

Finally i found the problem. So the problem was not in the speed calculation. Speed actually matched the lenghts of the path properly. Issue was in walk cycle itself. Before adding follow curve animation looks good because character actually moving on the same place so you cannot actually see the pace of the character properly, but once i added the follow curve result is completely different because character is shifts from same place so in my case character was dragging rear leg behind a bit so it was making feeling that something wrong with a time but its actually not.