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Is cache coherence a real issue, absent cache contention? AIUI, cache coherence protocols are sophisticated enough that they should readily adapt to workloads
by zozbot234 2y ago
Is cache coherence a real issue, absent cache contention? AIUI, cache coherence protocols are sophisticated enough that they should readily adapt to workloads where the same physical memory locations are mostly not accessed concurrently except in pure "read only" mode. So even with a single global address space, it should be possible to make this work well enough if the programs are written as if they were running on separate memories.
- monocasa 2y agoIt is because cache coherence requires extra communication to make sure that the cache is coherent. There's cute stratgies for reducing the traffic, but ultimately you need to broadcast out reservations to all of the other cache coherent nodes, so there's an N^2 scaling at play.