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Can you help me understand why removing L3 cache would speed things up? Genuinely curious! Increasing L1 and L2 make intuitive sense.
by amackera 5y ago
Can you help me understand why removing L3 cache would speed things up? Genuinely curious!
Increasing L1 and L2 make intuitive sense.
- jessermeyer 5y agoI think the idea is by removing L3 has allowed for an increase of both L1/2.
- lanna 5y agoI think he meant "despite not having L3"
- cogman10 5y agoRemoving L3 frees up transistors to be spent on L1/L2. On a modern processor the vast majority of transistors are spent on caches. Why this might help, ultimately, because the latency for getting something from L1 or L2 is a lot lower than the latency from L3 or main memory. That said, this could hurt multithreaded performance. L1/2 are used for 1 core in the system. L3 is shared by all the cores and a package. So if you have a bunch of threads working on the same set of data, having no L3 would mean doing more main memory fetches.
- vbezhenar 5y agoApple will invent L3 for workstation-level CPU.
- duskwuff 5y agoWild theory: for workstation-class systems, the 8/16 GB of on-package memory becomes "L3", and main memory can be expanded with standard DIMMs.
- skunkworker 5y agoIf you could get a Mac Pro with 32 to 48 firestorm + 4 icestorm cores with tiered memory caching and expandable to 2TB+ DDR4/DDR5 DIMMs. That would be an impressive machine for the small amount of wattage it would draw from the wall.