P4 Performance Revealed

Article: Willamette Performance Revealed
By: Paul DeMone (pdemone.delete@this.igs.net), November 22, 2000 1:23 am
Room: Moderated Discussions
Thank you for your kind words.

Taking the P4 down to 1 GHz is a good way of empirically checking its scaling factor and getting an idea of the relative performance of the PIII and P4 at the same clock rate (albeit one far below the intended operating point of the P4, and making it look somewhat worse than it is).

The P4 core is somewhat more latency resistent than P6 (larger re-ordering capability, greater memory buffering resources etc) but most if not all of this goes to balancing off the much higher clock rate (and relatively slower memory)

With P4's 128 byte cache lines the lower latency of DDR will basically cancel out the higher bandwidth of DRDRAM for most applications so I doubt there will be dramatic difference either way (except for cost :)

I think AMD will be hard pressed simply because the P4 is a highly innovative and brand new core right on the beginning of its ascending arc. It may look generally weak on many existing applications today but it is all uphill from here on in - architectural IPC improvements with the 0.13 um shrink, significant compiler improvements over the year or two, and an increasing amount of software optimized for it. And the big stick of course is clock rate scaling.

Forget the oft-quoted 2x the P6 pipeline depth figure, the relevent comparative figure - from uOP availability to conditional branch resolution is more like 16 vs 5 pipe stages, with two of the P4 pipe stages dedicated just to propagating signals on wires from one place on the chip to another. This processor is going to ramp in frequency like nothing anyone has seen before. I think the 0.18 um version will be limited to 2GHz or a little over but only because of power dissipation considerations, not by speed paths. And I don't see any reason the 0.13 um version won't eventually break 3 GHz.
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TopicPosted ByDate
P4 Performance Revealedshukla2000/11/21 05:28 PM
  P4 Performance RevealedPaul DeMone2000/11/22 01:23 AM
    P4 Performance RevealedDean Kent2000/11/22 06:06 AM
      P4 Performance RevealedPaul DeMone2000/11/22 09:55 AM
        P4 Performance RevealedDean Kent2000/11/22 11:35 AM
          P4 - are we seeing more specialisation?Lagrange2000/11/22 02:29 PM
            P4 - are we seeing more specialisation?Paul DeMone2000/11/23 01:32 PM
              P4 - are we seeing more specialisation?Lagrange2000/11/24 12:12 AM
                P4 - are we seeing more specialisation?Dean Kent2000/11/28 10:59 AM
            P4 - are we seeing more specialisation?Paul DeMone2000/11/23 01:40 PM
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