ClickHouse/dbms/Common/getNumberOfPhysicalCPUCores.cpp
Ivan 97f2a2213e
Move all folders inside /dbms one level up (#9974)
* Move some code outside dbms/src folder
* Fix paths
2020-04-02 02:51:21 +03:00

49 lines
1.6 KiB
C++

#include <Common/getNumberOfPhysicalCPUCores.h>
#include <thread>
#include <Common/config.h>
#if USE_CPUID
# include <libcpuid/libcpuid.h>
# include <Common/Exception.h>
#elif USE_CPUINFO
# include <cpuinfo.h>
#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();
}