With Zen set to arrive within the year, AMD is starting to get software ready for their revolutionary CPU architecture. According to a new Linux patch, AMD not only has Zen planned for this year but also a previously rumoured but never confirmed Zepplin CPU. Most interestingly is the connection between Zepplin and Zen which takes 3 letters from Zepplin, suggesting that they may be released, just as Piledriver and Vishera were also related for AMD.
According to the patch, Zepplin is part of the AMD’s Family 17h series of chips. This follows the previous 15h Bulldozer and its derivatives and the stellar K8(8h) and K10(10h). The 17h family is also expected to be the one Zen belongs too, with the K12 being the ARM-based lineup coming soon as well.
On Zen, the patch reveals some new information about how the LLC or Last Level Cache, usually the L3. Each Core Complex or Core Cluster of 8 threads shares 1 LLC unit. Given the use of SMT, we can expect Zen to be based on clusters of 4 cores. This is quite expected as larger CPUs use interconnects to link various different clusters of cores and their LLC together in order to function as a larger core. While Intel’s implementation carries a low penalty for accessing the LLC of another cluster in the chip, AMD’s L3 has been less robust so Zen will hopefully remedy this. You can see Intel’s Xeon E7 v3 design below with clusters formed by 2 cores and linked through buffered switches and interconnects.
Finally, Zen is also expected to feature up to 32 physical cores possible with 64 threads in total. This suggests that the massive Zen CPUs rumoured may actually come to fruition. This should allow AMD to take back some of that lucrative data centre and supercomputing market. All that remains is for Zen to finally deliver and bring AMD back into the black.