[Click] Problems in measuring delay time with CycleCountAccum

[Alessandro Coli]

Hi to all. I am trying to make some performace tests on some computers i have.

In this moment, i am interested into the average delay time introduced by the
click router.

To calculate it on the router (a dual processor Intel Xeon 2800 Mhz) i placed an
element "SetCycleCount" right after the Polldevice, and another
"CycleCountAccum" right before the ToDevice. I had thought to run a 120 seconds
test with packets of 64 bytes and a rate largely "light" for the router pc(at
this rate there are not packet losses) and, after, to read CycleCountAccum's
handlers and then calculate delay in microseconds like this:

Delay (microseconds) = (CycleCountAccum.cycles / CycleCountAccum.count) / 2800

And i did it. But, when i read the value of CycleCountAccum, i found incredible
high values! And, in fact, calculating the delay with the previous formula, i
got delays like 20800 microseconds!!!!

This is an absolute non sense. I thought the problem might be the fact i was
doing these measures on a dual processor pc (maybe CycleCountAccum does not work
well with dual processor pcs, I thought), so i tried to use SetCycleCount and
CycleCountAccum on another pc which is a normal mono-processor pc (Intel Xeon
2400 Mhz), to see if it was me not using these elements in the right way or if
it really was the dual processor thing (in this last case, i'd expect normal
delays in the second test i made).

Unfortunately, even on the monoprocessor pc, i got the same problem. Absolutely
high and nonsense delays. Maybe i am doing something wrong? Or are there some
problems with Xeon processors? Did something similar happen to you too?

Thanks

Alex