Author: Michael Chaly Date: Mon Nov 15 18:20:10 2021 +0100 Timestamp: 1636996810
Simplify Pv nodes related logic in LMR
Instead of having 2 separate conditions for Pv nodes reductions we can actually write them together. Despite it's not being strictly logically the same bench actually doesn't change up to depth 20, so them interacting is really rare and thus it's just a removal of extra PvNode check most of the time.
Old code only worked because there was probably a limit on how many cores/threads can reside within one NUMA node, and the OS creates extra NUMA nodes when necessary, however the actual mechanism of core binding is done by "Processor Groups"(https://docs.microsoft.com/en-us/windows/win32/procthread/processor-groups). With a newer OS, one NUMA node can have many such "Processor Groups" and we should just consistently use the number of groups to bind the threads instead of deriving the topology from the number of NUMA nodes.
This change is required to spread threads on all cores on Windows 11 with a 3990X CPU. It has only 1 NUMA node with 2 groups of 64 threads each.
