c# – 多次调用优先级最低的线程

using System;
using System.Threading;

      class PriorityTesting 
     { 
       static long[] counts; 
       static bool finish;

       static void ThreadFunc(object iThread) 
       { 
         while(true) 
         { 
           if(finish) 
              break; 
           counts[(int)iThread]++; 
         } 
       }

       static void Main() 
       { 
         counts = new long[5]; 
         Thread[] t = new Thread[5]; 
         for(int i=0; i<t.Length; i++)  
         { 
           t[i] = new Thread(ThreadFunc); 
           t[i].Priority = (ThreadPriority)i; 
         } 
         // Запускаем потоки 
         for(int i=0; i<t.Length; i++) 
           t[i].Start(i);

         // Даём потокам возможность поработать 10 c 
         Thread.Sleep(10000);

         // Сигнал о завершении 
         finish = true;

         // Ожидаем завершения всех потоков 
         for(int i=0; i<t.Length; i++) 
           t[i].Join(); 
         // Вывод результатов 
         for(int i=0; i<t.Length; i++) 
           Console.WriteLine("Thread with priority {0,15},Counts: {1}",(ThreadPriority)i,counts[i]); 
       }   
     }

汇编：

$mcs PriorityTesting.cs
$mono PriorityTesting.exe

输出：

Thread with priority          Lowest,Counts: 178544880
Thread with priority     BelowNormal,Counts: 167783608
Thread with priority          Normal,Counts: 160593225
Thread with priority     AboveNormal,Counts: 79123315
Thread with priority         Highest,Counts: 81623159

具有最低优先级的线程如何比具有最高优先级的线程调用多次？

UPD：

具有2个内核的CPU上的相同代码(Windows,.NET)：

Thread with priority         Lowest,Counts:    7608195 
 Thread with priority    BelowNormal,Counts:   10457706 
 Thread with priority         Normal,Counts:   17852629 
 Thread with priority    AboveNormal,Counts:  297729812 
 Thread with priority        Highest,Counts:  302506232

为什么不同？