#include #include #if !defined(ARCADIA_BUILD) # include #else # include #endif #if USE_CPUID # include #elif USE_CPUINFO # include #endif unsigned getNumberOfPhysicalCPUCores() { #if USE_CPUID cpu_raw_data_t raw_data; cpu_id_t data; /// On Xen VMs, libcpuid returns wrong info (zero number of cores). Fallback to alternative method. /// Also, libcpuid does not support some CPUs like AMD Hygon C86 7151. if (0 != cpuid_get_raw_data(&raw_data) || 0 != cpu_identify(&raw_data, &data) || data.num_logical_cpus == 0) return std::thread::hardware_concurrency(); unsigned res = data.num_cores * data.total_logical_cpus / data.num_logical_cpus; /// Also, libcpuid gives strange result on Google Compute Engine VMs. /// Example: /// num_cores = 12, /// number of physical cores on current CPU socket /// total_logical_cpus = 1, /// total number of logical cores on all sockets /// num_logical_cpus = 24. /// number of logical cores on current CPU socket /// It means two-way hyper-threading (24 / 12), but contradictory, 'total_logical_cpus' == 1. if (res != 0) return res; #elif USE_CPUINFO uint32_t cores = 0; if (cpuinfo_initialize()) cores = cpuinfo_get_cores_count(); if (cores) return cores; #endif /// As a fallback (also for non-x86 architectures) assume there are no hyper-threading on the system. /// (Actually, only Aarch64 is supported). return std::thread::hardware_concurrency(); }