![]() This new feature dynamically assigns the most active threads in the system to the more efficient NUMA nodes something the Windows scheduler would do if it properly handled this NUMA configuration. Today, Oct 29 2018, AMD updated their Ryzen Master utility to add ‘ Dynamic Local Mode‘. However, disabling half the system’s CPU cores is not ideal and is problematic when an application’s thread load grows beyond that limitation. This same operation can be done with our Process Lasso. This odd case of NUMA nodes without any local memory causes the Windows scheduler to assign threads without regard to the more optimal dies in the 2990wx and 2970wx.ĪMD initially combated this by allowing a user to disable the less efficient NUMA nodes so that performance critical applications can always run on the more optimal CPU dies. It seems that the Windows scheduler was designed with the understandable assumption that every NUMA node has local memory. Linux is able to handle this esoteric NUMA configuration much better than Windows. NUMA nodes 1 and 3 must pass all requests through the Infinity Fabric. NUMA nodes 0 and 2 each have access to two of the four possible memory channels, so each has direct access to half the system memory. In the case of the 2990wx, node 0 represents logical cores cores 0-15 and node 2 represents 16-31. Note: For Threadripper processors, the DMA CPU cores are the first half, starting at 0 and numbered sequentially. Therefore, the configuration for 4 memory channels is: Node 0: - low latency The NUMA mapping is thus that 2 of the nodes have *zero* node local memory! Node local memory is the memory closest to a CPU, having the lowest latency. ![]() ![]() AMD Threadripper 2990wx ArchitectureĪMD exposes each die as a NUMA node. ![]() This results in additional memory access latency for 2 of the dies, or 1/2 the CPU cores. The other two dies must pass all memory and PCIe requests through the Infinity Fabric that links the CPU dies together. As has been well reported on tech sites, the core heavy 2990wx and 2970wX have an unusual configuration where only 2 of the 4 dies have direct access to channels of system memory (DMA). Here at Bitsum we’ve been closely following the AMD Threadripper 2nd gen releases. UPDATE: Bitsum is testing our own Dynamic Local Mode implementation – See this forum thread for more information. ![]()
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