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It is the gall wasp season. These are weird wasps that inject chemicals into plants, and repurpose their growth patterns, like gadget exploits in code. This is a mossy rose gall, you can see a smaller one starting to grow on the left as well.
I have been taking notes for this for a while, but started a conversation on Bsky with David Aronchick yesterday about it so thought I should write this up in more detail.
AMD Zen EPYC shipped a maximum of 32 cores in 2017, 64 with Zen 2 in 2019, 96 with Zen 4 in 2022 or 128 smaller cores with Zen 4c, and then 128 for Zen 5 in 2024, with 192 in Zen 5c. So four times as many cores in eight years, doubling every two years in a Moore's law type mode.
Within the cores, while they don't run any faster, we have started doubling up compute units, from 32 bit registers to 64 bit registers (2003 for amd64), 128 bit SSE (1999), 256 bit AVX (2011), 512 bit AVX (2017), and new Zen5 hardware can execute four 512bit operations per cycle. This is far above the memory bandwidth limits so is only useful for doing a lot of compute over cached items.
Over that period AMD EPYC went from a maximum of 8 channels of DDR4 memory to 12 channels of DDR5, which roughly doubled the maximum memory bandwidth, halving the bandwidth per core for the maximum core configurations.
