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Bob Colwell mentions originally doing out of order design at Multiflow. He was a key player in the Pentium Pro out of order implementation. https://www.sigmic
by chasil 1y ago
Bob Colwell mentions originally doing out of order design at Multiflow.
He was a key player in the Pentium Pro out of order implementation.
https://www.sigmicro.org/media/oralhistories/colwell.pdf https://www.sigmicro.org/media/oralhistories/colwell.pdf
"We should also say that the 360/91 from IBM in the 1960s was also out of order, it was
the first one and it was not academic, that was a real machine. Incidentally that is one of the
reasons that we picked certain terms that we used for the insides of the P6, like the
reservation station that came straight out of the 360/91."
Here is his Itanium commentary:
"Anyway this chip architect
guy is standing up in front of this group promising the moon and stars. And I finally put my
hand up and said I just could not see how you're proposing to get to those kind of
performance levels. And he said well we've got a simulation, and I thought Ah, ok. That shut
me up for a little bit, but then something occurred to me and I interrupted him again. I said,
wait I am sorry to derail this meeting. But how would you use a simulator if you don't have a
compiler? He said, well that's true we don't have a compiler yet, so I hand assembled my
simulations. I asked "How did you do thousands of line of code that way?" He said “No, I did
30 lines of code”. Flabbergasted, I said, "You're predicting the entire future of this
architecture on 30 lines of hand generated code?" [chuckle], I said it just like that, I did not
mean to be insulting but I was just thunderstruck. Andy Grove piped up and said "we are not
here right now to reconsider the future of this effort, so let’s move on"."
- phire 1y ago> Bob Colwell mentions originally doing out of order design at Multiflow. Actually no, it was Metaflow [0] who was doing out-of-order. To quote Colwell: "I think he lacked faith that the three of us could pull this off. So he contacted a group called Metaflow. Not to be confused with Multiflow, no connection." "Metaflow was a San Diego group startup. They were trying to design an out of order microarchitecture for chips. Fred thought what the heck, we can just license theirs and remove lot of risk from our project. But we looked at them, we talked to their guys, we used their simulator for a while, but eventually we became convinced that there were some fundamental design decisions that Metaflow had made that we thought would ultimately limit what we could do with Intel silicon." Multiflow, [1] where Colwell worked, has nothing to do with OoO, its design is actually way closer to Itanium. So close, in-fact that the Itanium project is arguably a direct decedent of Multiflow (HP licensed the technology, and hired Multiflow's founder, Josh Fisher). Colwell claims that Itainum's compiler is nothing more than the Multiflow compiler with large chunks rewritten for better performance. [0] https://en.wikipedia.org/wiki/Metaflow_Technologies https://en.wikipedia.org/wiki/Metaflow_Technologies [1] https://en.wikipedia.org/wiki/Multiflow https://en.wikipedia.org/wiki/Multiflow
- chasil 1y agoI thoroughly acknowledge and enjoy your clarification.