Chapter XI: Conclusion
Well, I think we should take a break now. Especially, since we have already collected a lot of interesting material and now it’s high time we summed it all up and drew some conclusions. Besides, I believe that if you read that far, you definitely need a break, too. :)
We would like to say that it wasn’t easy or fast before we figured out all the tiniest details of the replay mechanism. In fact, we have postulated the existence of replay system back in February 2004, and since then we have been studying its working principles and the influence it imposes over all other components of the processor architecture.
Besides, when we were working on the article, we faced an evident contradiction. On the one hand, replay and its features are really interesting and haven’t been yet described in that much detail anywhere. So, we feel like providing as much of the indepth info as possible about the Pentium 4 processor operation.
On the other hand, this is a very specific processor peculiarity, and we have no idea how interesting this is going to be for you, our readers. We are really uncertain that most of you ever go that far into the details...
So, in order to make this subject interesting to the most of X-bit readership groups, we did our best to deliver the message in a simple and easy to understand manner, at the same time retaining the technical correctness and level of detail, in order to please the techy part of our visitors, too.
It is actually up to you to decide if we managed to accomplish our goals or not. If it was an interesting read, if you remembered and learned something, if you realized at least for a second how complex the processor architecture actually is, then our efforts were not vain :)
So, let’s make some conclusions about the replay and our investigation of the Pentium 4 micro-architecture.
Replay is an inalienable part of NetBurst ideology. This part of it has been unknown to the general public for a while. But this mechanism ensures proper functioning of the Pentium 4 micro-architecture that is why it is worth paying special attention to.
Replay is negative for the processor performance. However, this is price we had to pay for longer pipeline and considerably higher working frequency. It is quite possible that complex replay mechanism, its negative influence on the processor performance, and additional overheating it causes forced Intel to cancel Tejas core, which was supposed replace Prescott. At least, this hypothesis explains what we see well enough (of course, only Intel management knows the true motives behind this decision).