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Netflix and others are discovering one of the reasons why I think one socket servers are the future. Single sockets are big enough for almost every workload, a
by pclmulqdq 4y ago
Netflix and others are discovering one of the reasons why I think one socket servers are the future. Single sockets are big enough for almost every workload, and come with a ~10% perf uplift from not having inter-socket cache coherence nonsense.
- pdpi 4y agoModern x86 CPUs typically have three layers of caching, where L1 and L2 are per-core, and only L3 is shared across all cores. You still have to solve all the cache coherency issues, and everything in the article still applies, even with just one socket.
- pclmulqdq 4y agoWhile that is true, and AMD CPUs are even worse thanks to chiplets, the latency and bandwidth of the inter-chip cache coherent interconnect is a lot worse than the on-chip (or on-socket in AMD's case) buses. That is the expensive part of it. Cache line sharing (false and true sharing) still hurts in 1S configurations, but it hurts a lot less.