Servers for an Accelerated Future
> We selected the AMD EPYC 7642 processor in a single-socket configuration for Gen X. This CPU has 48-cores (96 threads), a base clock speed of 2.4 GHz, and an L3 cache of 256 MB. While the rated power (225W) may seem high, it is lower than the combined TDP in our Gen 9 servers and we preferred the performance of this CPU over lower power variants. Despite AMD offering a higher core count option with 64-cores, the performance gains for our software stack and usage weren’t compelling enough.I find this a bit puzzling for density reasons. I can definitely appreciate the clock speed benefits. One 64-core part (AMD EPYC 7742) has the same TDP of 225W, so power should be in the same ballpark. There's also lower clocked 64-core SKUs with 200W TDP. I can't imagine price would be major factor for a company of Cloudflare's size, but it's definitely true that the 48-core part is much cheaper. There's also the 7H12 with a higher base clock than the 48-core part, but its TDP is 280W.All of these EPYC chips have the same monstrous 256MB of L3, so maybe part of Cloudflare's workloads maxes out the cache before being able to feed all 64 cores, but that's a bit wishywashy. Maybe since they also all have the same PCIe lane capacity 48 cores is the sweet spot.The 64-core parts still seem like a nobrainer.