I haven't read about P4 and NetBurst in a long t ime, but is mu memory serve me right, P4 is usually less than 1ipc due to its very long pipeline (31 stages IIRC) that is very prone to pipeline stall. Modern processor can also do many thing faster. I think P4 takes ~110 cycles for integer division, while modern cpu can do in ~30-40 cycles. And IIRC, P4 cannot flush the division unit so if branch/jump prediction is wrong and division is speculated, it was to wait until the division unit finish computation before it can resume execution.
I haven't read about P4 and NetBurst in a long t ime, but is mu memory serve me right, P4 is usually less than 1ipc due to its very long pipeline (31 stages IIRC) that is very prone to pipeline stall. Modern processor can also do many thing faster. I think P4 takes ~110 cycles for integer division, while modern cpu can do in ~30-40 cycles. And IIRC, P4 cannot flush the division unit so if branch/jump prediction is wrong and division is speculated, it was to wait until the division unit finish computation before it can resume execution.