>i guess printf doest take a lot of processing :|
printf doesn't do much internal processing, despite the length of the code for it. ;) The performance hits come from writing to an external device, which is extremely slow when compared to the simple internal data movement of a sort.
>but isnt the clock is supposed to be processor clock and i think
>it doesnt take into account the interupts for other device into account :|
The processor doesn't stop ticking just because you call an interrupt for a device.