Only with 40 threads running on the two CPUs of the system the NUMA-awareness becomes important.įor 2048 MB hash the speed improvement from using Large Pages is about 6%. up to 20 threads, Windows and the Intel Xeons do a good job of providing excellent performance without any NUMA awareness. When the engine can run fully on a single CPU, i.e. The impact of the Large Pages and the NUMA-awareness on the measured average node speed was as follows: The system has two CPUs and two NUMA nodes every CPU with 20 cores resides on its own NUMA node.Ī two minute benchmark was run on a number of positions using 1, 6, 20 and 40 threads with hash memory set at 2048 MB. This test system is a 40-core dual Intel Xeon v4 box running at 2.3 GHz speed having 80 virtual processors (40 cores with hyper-threading) under Windows 10. To avoid this, you should set the NUMA Offset parameter to different values in the different Houdini instances.įor example, if you want to run two Houdini instances with 6 threads each on 12-core hardware, you should use NUMA Offset 1 for the second instance so that it will allocate its 6 threads on the second NUMA node. If you're simultaneously running multiple Houdini Pro instances they will by default compete for the resources on the same NUMA nodes. The speed gain depends on the number of cores, the motherboard and CPU brand. Houdini Pro detects the NUMA configuration at start-up and will adapt its memory management and thread interaction based on the different NUMA nodes that are available. Most CPU mother boards with multiple sockets employ the so-called "NUMA" architecture. Houdini will try to create large page memory blocks of increasing size and show a summary of the results. Run Houdini in a command window (simply by double-clicking on the executable) and type lp followed by Enter.
You can test the availability of Large Pages with the lp command. After a while the Windows memory becomes too fragmented for large page allocation, and Houdini will fall back to standard memory page usage. Very often large memory pages will only be available shortly after booting Windows. IMPORTANT: You'll also need to run your chess GUI with administrative rights (" Run as Administrator") or disable UAC in Windows.
You may have to logoff or reboot for the change to take effect.
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