Hi experts,
I want to knows why there are 4 core cores per cluster in ARM big.Littte architecture?
Is it possiable if we make more cores per cluster? if not, what is the limitation?
So an IP-customer cannot just "plug" n Cortex-A53 together, but buys a single, dual or quad CA53 IP?
See, we just like to understand, why certain companies (as the before mentioned NXP) build chips with 8 cores but in 2 clusters.
BTW: Cars have mostly four wheels because of physical/technical reason. So there is surely a technical reason for the max. 4 cores/cluster choice. But it is ok, if ARM does not want to share this with everyone ;-)
42bis,
The technical reason is allowing more configurations at RTL synthesis time means more combinations to validate, which is a lot of work. There was a design decision to limit it to 4, a long time ago, for those products. You could imagine that the logic that connects the cores together only has 4 ports in the design. If you configure 2 cores, some of that logic is optimized away. But there are only 4 combinations to work out - 1, 2, 3 and 4 cores in a cluster. Imagine if we supported 32 cores in a cluster - that'd be 8x the work to validate it. To cover that we might decide that you can only have 1, 2, 3, 4, 8, 16 and 32 (which is not even twice the work). Aside from that you have to cover power consumption and area concerns with larger systems. That's the limitation. We only wish it was as simple as "copy & paste"
That's an extremely simple view of things, but you get the idea, right?
Ta,
Matt
Thanks Matt for the insights. I get the idea.