how to use jiffies in printk



Hello,
I am a newbie so please excuse my ignorance. I am trying to print
the time it takes to transmit 10000 packets in my computer.
So, in the standard e1000_main.c code (I have a Intel Gigabit card)
e1000_xmit_frame, I have added the following lines:

azeem_count++;
if(azeem_count % 10000 == 0)
printk(KERN_INFO "%u %u\n", jiffies_to_usecs(jiffies),
azeem_count);

where azeem_count has been initialized as a static unsigned int = 0.
But the numbers I am getting are giving me incorrect values when I
compare it with back of the envelope calculations.

So, my question is, how am I supposed to use this "jiffies".
(I have a 3.0 GHz HT P4).

Thanks.

.