![]() ![]() Arm here discloses a maximum SLC of up to 512MB per die, meaning 4MB per node, while oddly enough saying the CMN-600 only supports 128MB, which technically is incorrect given that the reference manual says it goes up to 256MB at 4MB per node at 64 nodes. Ampere never confirmed their mesh layout, but this seems to be the only explanation of how they’d achieve a core count that high on the CMN-600.Īlongside 128 RN-Fs, hosting up to 256 cores, the chip hosts up to 128 HN-F home nodes, meaning nodes in which the SLC (System Level Cache) resides. Arm explained that the 64-core limit is through native cores connected to RN-F’s or through CALs, and that it’s actually possible to host more cores when you integrate them into the mesh through DSU (DynamiQ Shared Units). For attentive readers, it might be weird to see Arm say that the CMN-600 only supports up to 64 cores when we have 80-core designs such as the Altra out there. The actual maximum number of cores in a mesh has grown from 64 to 256, the latter number achievable through 128 RN-F request nodes each with 2 cores through a CAL (Component Aggregation Layer). CAL: Component Aggregation Layer – A block that houses two CPU cores connecting to one RN-F port.HN-F: Fully coherent Home Node – A block of SLC cache with Snoop Filter.RN-F: Fully coherent Request Node – Typically a CPU core, a CAL with two cores, or a DSU cluster.Starting off with the basic characteristics of the new design, the important big new feature is the fact that the mesh now has grown from a limit of 8 x 8 nodes (64) to 12 x 12 (144), allowing Arm to increase the number of CPUs on a single mesh and silicon die. The IP was announced quite some time ago, but has been a mainstay of Arm’s infrastructure IP for some time now, with it seeing some iterations in terms of IP revisions, with r2 introducing some important changes such as larger caches and CCIX capability.Īlong with the V1 and N2, Arm today is also announcing a new generation CMN product in the form of the new CMN-700, promising much larger improvements to how Arm’s mesh network operates and what it is capable of in terms of scalability, performance, and flexibility. ![]() It’s been a whole 5 years since we last wrote about Arm’s Coherent Mesh Network, the current generation CMN-600. The CMN-700 Mesh Network - Bigger, More Flexible
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