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> Was the industry ready for this concept of a computer having a number of meaningfully different kinds of cores? The industry didn’t have a choice. The marke

> Was the industry ready for this concept of a computer having a number of meaningfully different kinds of cores? The industry didn’t have a choice. The market was demanding higher performance within the same thermal envelope and the same energy consumption. These are mobile devices, you can’t put a bigger heat sink on it and then crank up the power. You can find tons of academic literature discussing the necessity of this development (along with many other things that have come to pass), how it would work, etc. in the decade leading up to the introduction. ARM didn’t just release it to the world and say “Surprise!” We knew it was coming, we just didn’t do the best job of preparing for it.

MichaelZuo 3y ago
Why not just run some of the high performance' cores at a much lower clock rate? Much smaller silicon and software changes would have been needed to allow for just two different clock rates. What was the argument for designing two different types of cores instead?
- Osiris 3y ago
  AMD’s approach is similar to this. The efficiency core is the same core with less cache and lower clocks. It’s not a different micro architecture like in ARM and Intel designs.
- Kon-Peki 3y ago
  High performance cores use a lot of transistors and take up a lot of space. When you are aiming for high performance, this is a good tradeoff. The efficiency cores are physically smaller, cheaper, etc. One you reduce the performance expectations to the point where they satisfy the requirements, they are a much better choice. The efficiency core has more perf-per-watt than a clocked-down performance core. It seems counterintuitive. But when your budget for transistors is X and your budget for power draw/heat dissipation is Y, and there is no leeway whatsoever, the big.LITTLE concept gets you more aggregate performance.
  - MichaelZuo 3y ago
    Can you link an analysis for that where small cores have more perf-per-watt then a clocked down big core? From what I understand the transistors aren't mostly for enabling the higher clock speed at all, they allow for wider cores that do more per cycle. It doesn't seem clear at all that they would be less efficient than a narrower design that does less per cycle, if clocked much lower to yield the same final performance per cycle.

MichaelZuo 3y ago

Why not just run some of the high performance' cores at a much lower clock rate? Much smaller silicon and software changes would have been needed to allow for just two different clock rates. What was the argument for designing two different types of cores instead?

Osiris 3y ago
AMD’s approach is similar to this. The efficiency core is the same core with less cache and lower clocks. It’s not a different micro architecture like in ARM and Intel designs.
Kon-Peki 3y ago
High performance cores use a lot of transistors and take up a lot of space. When you are aiming for high performance, this is a good tradeoff. The efficiency cores are physically smaller, cheaper, etc. One you reduce the performance expectations to the point where they satisfy the requirements, they are a much better choice. The efficiency core has more perf-per-watt than a clocked-down performance core. It seems counterintuitive. But when your budget for transistors is X and your budget for power draw/heat dissipation is Y, and there is no leeway whatsoever, the big.LITTLE concept gets you more aggregate performance.
- MichaelZuo 3y ago
  Can you link an analysis for that where small cores have more perf-per-watt then a clocked down big core? From what I understand the transistors aren't mostly for enabling the higher clock speed at all, they allow for wider cores that do more per cycle. It doesn't seem clear at all that they would be less efficient than a narrower design that does less per cycle, if clocked much lower to yield the same final performance per cycle.