Intel is moving away from its ringbus architecture for its upcoming server and hedt processors. The ring bus would no longer be sufficient for the ever-increasing number of cores. Instead, a mesh network will take care of the communication between the cores.
Because the number of cores in processors is constantly increasing, Intel does not consider the ring bus architecture that connects cores to L3 cache to be sufficient. To make it easier to scale with core numbers and to reduce latencies between cores and caches, Intel has developed a mesh topology for its upcoming major server processors and for the Skylake-X processors for X299-hedt motherboards. With the new structure, the cores also have more bandwidth, Hardware.info reports.
The introduction of the ring bus architecture to Nehalem-EX server processors was intended to reduce the number of wires, or metallic interconnects. Such wires took up too much space and the ring bushing would simplify the metal layer and reduce latencies. The scalability turned out to be insufficient, because with the last generations of Xeons, two ring buses had to be tied together in order to connect all cores, resulting in more latency.
With the mesh network, each core is connected to a network of interconnects with its own L3 cache. That network also connects to the memory controllers and other components such as PCI-e controllers and socket interconnects. Each node would yield a clock tick latency, so in a grid of 4×5 cores the latency would never exceed nine ticks.
The mesh network will be implemented first in the Skylake-X processors, with the first models coming at the end of this month. For regular server processors, the network in the Xeon Scalable Family processors will be used. That scalable indicates that the number of cores in products can easily be varied, the Skylake-EP series would grow from Broadwell-EP’s 24 cores to 28 cores. The mesh topology, which is also used in Knights Landing, would witness those chips scale to at least 72 cores. The upcoming Core i9-7980XE, with a modest eighteen cores in this light, has a 4×5 topology of its cores, as can be concluded from a die-shot.
Die-shot of Intel Core i9-7980XE processor