4 ms·
There actually aren't really any benefits outside of manufacturing. Trace length is a marginal factor in memory performance/latency, and having the memory on-pa
by chungus_khan 6y ago
There actually aren't really any benefits outside of manufacturing. Trace length is a marginal factor in memory performance/latency, and having the memory on-package versus only slightly further away doesn't mean much. I'm not sure exactly where the idea that having the memory on-package was so beneficial came from, especially considering the M1 actually has fairly poor memory latency (though within the expected normal range for LPDDR4X):
https://www.anandtech.com/show/16252/mac-mini-apple-m1-tested https://www.anandtech.com/show/16252/mac-mini-apple-m1-teste...
As far as HSA/unified memory architecture, PCIe 4.0 has enough bandwidth to comfortably access main memory for applications that support it (and vice versa with GPU memory), although I imagine most high-performance GPU workloads will do better primarily operating on dedicated GPU memory (especially given that a single M1 core can already saturate the memory controller on its own).
- tambourine_man 6y agoThis is not my area of expertise, but I’ve seen concerns of implementing the unified memory architecture off chip. But maybe it’s just that it hasn’t been done yet.
- chungus_khan 6y agoThat doesn't have any impact. The memory isn't on-chip, it's just on-package. This makes it no different from if it was fully external. This has also not been a problem for any other unified memory system (which typically also do not include memory on-package), and I can't see any reason why it would matter.