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They expect that some of the cores on the wafer will fail, so they have redundant links all throughout the chip, so they can seal off/turn off any cores that fa
by shrubble 2y ago
They expect that some of the cores on the wafer will fail, so they have redundant links all throughout the chip, so they can seal off/turn off any cores that fail and still have enough cores to do useful work.
- why_only_15 2y agoMy understanding is that they mask off or otherwise disable a whole row+column of cores when one dies
- wtallis 2y agoThat's way too wasteful. Take a look at https://fuse.wikichip.org/news/3010/a-look-at-cerebras-wafer-scale-engine-half-square-foot-silicon-chip/2/ https://fuse.wikichip.org/news/3010/a-look-at-cerebras-wafer... and specifically the diagram https://fuse.wikichip.org/wp-content/uploads/2019/11/hc31-cerebras-mem-yield.png https://fuse.wikichip.org/wp-content/uploads/2019/11/hc31-ce... The fabric can effectively route signals diagonally to work around an individual defective core, with a displacement of one position for cores in the same row from that defect over to the nearest spare core. That's how they get away with a claimed "1–1.5%" of spare cores.