[ixp1200] microengine execution percentage

Hi, I am using chapter 9 code for receive which runs on two microengines in my project.The execution statistics show that microengine 0 all four threads are underutilized with execution time 0.1% and with thread 0 0.1 % abort time.while microengine 1 threads show a good percentage. Can anyone explain why this happens.below is the switch statement used in the textbook code switch(thread_id()) { case 0: next_thread = 4; break; case 1: next_thread = 5; break; case 2: next_thread = 6; break; case 3: next_thread = 7; break; case 4: next_thread = 1; break; case 5: next_thread = 2; break; case 6: next_thread = 3; break; case 7: next_thread = 0; break; Thanks, shweta