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Like the post says near the end, this seems like at least partly the result of AMD not being the size of Intel or Apple, so not being able to have the staffing
by twotwotwo 3y ago
Like the post says near the end, this seems like at least partly the result of AMD not being the size of Intel or Apple, so not being able to have the staffing to create, validate, etc. two radically different large and small designs. So instead they tweak the synthesis of one design to lower max freq in exchange for area. There's less perf downside to using these cores, but less area/power upside.
The perf impact of this or any hybrid design is also blunted by the power/cooling limits on non-hybrid designs: you can't afford to blast all the full-size cores on the chip at the max theoretical frequency at once anyway. Then, at the other end, lightly-threaded workloads can run mostly or only on the larger cores, so they're not heavily impacted either.
If there's a way this ends up fun for consumer folks that follow this stuff, it'd probably be by allowing products w/more cores. In server chips using Zen 4c (Bergamo), more cores is explicitly the focus. On their desktop platform, one CCD of full-sized cores and one of smaller cores would allow a 24C two-CCD package. That would add another "flavor" of CPU, the way X3D is another "flavor", but I suspect there are applications where the extra throughput could help. No particular hints that this is part of their plans, to be clear.
- mastax 3y agoAnother part of it is that AMD's Zen core is a much more area-efficient design than Intel's Raptor Cove (et. al.) core. Raptor Cove is 7.43mm^2 (Intel 7, Excluding L2/3 Cache) while Zen4 is 3.84 mm^2 (TSMC N5, Excluding L3 Cache). Intel 7 and TSMC N5 have comparable densities, though the numbers have changed over time and it depends on the transistor libraries used, etc. AMDs core is close to a clean-sheet redesign and, as Gelsinger has admitted, Intel has lost design leadership. The Zen4c core has a comparable size to the Gracemont E-cores, so they don't really need a separate design.
- beebeepka 3y agoIt will be exciting to see two CCDs with big and c cores. However, Problem is, this many cores need bandwidth and two channel is hardly ideal. I hope AMD would at least double the channels on desktop and laptop. How else are they going to feed the future beefy APUs?
- twotwotwo 3y agoRight, more bandwidth would really help mobile iGPUs, maybe more than it'd help many-core CPUs. I'm not sure if they want to sell super-beefy consumer iGPUs, or if AM5 is physically capable of having more channels. But it would be shiny, and seems like it's worked out in the large Apple SoCs.