# Tag Info

1

What do you think happened: All the engineers at Intel, AMD and IBM read that a pipeline can only deliver one result per cycle, and they said "oh well, that's it then, can't make these processors any faster". Or did they read this and said: "Can't deliver more than one result per cycle? We'll see about that!". For a good introduction to the Haswell ...

22

First, as Camil Staps' comment and Turbo J's answer point out, the measurement was 113,093 Dhrystone MIPS not native MIPS. The Ivy Bridge microarchitecture of the i7 3630QM can only commit 4 fused µops per cycle, though it can begin execution of 6 µops per cycle. (The number of fused µops in a trace of code is roughly equal to the number of instructions; ...

2

The Drystone benchmark is from 1984, and the corresponding nominal 1 MIPS VAX machine is not very efficient in modern terms. Even a Cortex M3 delivers 1,25 DMPIS / MHz. Intel Core achitecture processors can indeed run multiple instructions in parallel in a single core, because there are multiple computing units present.

8

Some dark magic happens on the inside of modern processors, but your thoughts are definitely along the right lines. The key to understanding the efficiency of modern processors is realising that they are superscalar. From Wikipedia (emphasis mine): A superscalar CPU architecture implements a form of parallelism called instruction-level parallelism ...

0

As well as all the other answers, there are also a few other considerations which may not affect CPU speed directly but make building anything around that CPU quite difficult; In short, above DC, radio frequency becomes an issue. The faster you go, the more inclined everything is to act as a giant radio. This means that PCB traces suffer crosstalk, the ...

0

The answers to your questions are: Yes, there is a physical limit to CPU speed. The highest theoretical limit will be set by how fast a "switch" can switch states. If we use the electron as the basis of the switch, we use the Bohr radius $$r = 5.291 x 10^{-11}$$ and the fastest speed possible $$c = 3 x 10^8,$$ to calculate the frequency  F = 1/t = c/2 \ ...

0

Dude, relax. You don't need to be a prodigy to be an accomplished engineer. It'd be helpful but it isn't what is going to make you a star. Remember hard work pays off more than raw talent. The greatest items in history had few what you would call prodigies working on them, if any. Computer scientists and engineers work together through various methods, ...

2

Abstraction is the idea of encapsulating complexity into a "black box" which can be utilized by only knowing its defined properties, not its inner workings. This lets someone design a "computer" without needing to know all the details of how each "chip" works, how the power supply or monitor works, etc, but rather only needing to select or contract ...

6

That's because there is a limit to the clock frequency but not to the pipeline length. When you make a digital circuit the maximum clock frequency is determined by the so called "critical path": you have a clocked register, some combinational logic and another clocked register. If your clock period is shorter than the time required from the combinational ...

-2

In short Marketing During the 90's GHz sold CPU's "buy the latest Intel processor, its running at 1 billion gigaflop's". courses.engr.illinois.edu/cs232/fa2011/lectures/l14.pdf

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