3 ms·
> M1 Ultra has one cluster of 4 E cores (E0) This seems weird or wrong. Given that M1 Ultra are two M1 Max bolted together (apparently in a way that is somewha
by dfox 4y ago
> M1 Ultra has one cluster of 4 E cores (E0)
This seems weird or wrong. Given that M1 Ultra are two M1 Max bolted together (apparently in a way that is somewhat unconventional, but in effect neat) I don't see how that would be done in hardware or even why the authors would want to it work like that (it is my understanding that the whole reason for clusters is that whole cluster has same clock, which is somewhat hard and pointless to do when half of it resides on different die).
Maybe it is only an software abstraction and in HW there are two 2xIcestorm clusters?
- zamadatix 4y agoFrom watching the Asahi IRC over time this sounds right, 6 clusters total. Like you say I wouldn't be surprised if macOS lumps them together from a scheduling perspective to keep low performance scheduling (where going across the interconnect doesn't matter as much anyways) simpler.
- dfox 4y agoI somehow assume that the interconnect between the M1 Ultra dies boils down to bunch of AHB ports more or less directly connected together through the interposer (with only minimal pad logic). This seems consistent with both the performance profile of the thing and with macOS mostly ignoring the topology for scheduling purposes.