![]() ![]() As Microsoft OpenMP code is supported by Intel libiomp5 (and maybe by some version of the llvm), it is possible to set affinities by replacing the Microsoft library linkage. Reluctantly, I have changed much OpenMP code to use #if _OPENMP >= 23017 so as to not use recent features with Microsoft compiler and to conform to Microsoft subset of OpenMP elsewhere. Which is rejected with same error message as for(. ) is accepted when not preceded by #pragma omp for, but not It is still limited to the combination of OpenMP 2.0 and, in the case of C source code, the C89 standard, even though a number of C99 features have been introduced for use exclusive of OpenMP constructs. I just did some more tests on the OpenMP support in the most recent Microsoft VIsual Studio. Technically, NUMA may refer to a variety of features which don't appear to be under discussion here. In order to take advantage of local memory when applying affinity settings, it was necessary to turn on enable NUMA setting in BIOS. They were shipped with the BIOS "NUMA disabled" meaning that cache lines were stored alternately by each CPU on remote and local memory. The original post seemed possibly to refer to the NUMA enabling BIOS option frequently provided on early 2-socket NUMA platforms. Xeon processors have processor numbering such as E5-1620, E5-2620, E5-4620, E5-8620), where the -n (1,2,4,8) is the maximum number of sockets that the CPU can be used in.ġ) motherboard must have multiple socketsĢ) motherboard must have multiple memory subsystems (populated)ģ) motherboard must have multiple CPUs (not all sockets need to be filled)Ĥ) only memory subsystems with CPU are usableĥ) BIOS must configure memory subsystems for NUMA configuration (else configure for interleaved use) Access to the local memory subsystem is faster than access to the other memory subsystem(s).Ĭore i7 only supports 1 socket, thus only one memory node (which can have 1, 2. ![]() Each CPU (socket) can access its own memory subsystem as well as access the other memory subsystem(s). On a 2 socket system, each socket has its own memory subsystem. NUMA nodes have nothing to do with virtualization. Note, some motherboards with dual (more than 1) socket can have a single memory subsystem, thus 1 node. As stated earlier, excepting for KNL, the number of NUMA nodes is typically tied to the number of CPUs (sockets), as each socket may have separate memory slots adjacent to the CPU. The logical processors are the hardware threads that the CPU is configured to run (HyperThreading is enabled or disabled as a BIOS setting). This one CPU has several logical processors. ![]()
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