ClickHouse/dbms/src/Common/getNumberOfPhysicalCPUCores.cpp
2019-01-28 16:24:55 +03:00

54 lines
1.8 KiB
C++

#include <Common/getNumberOfPhysicalCPUCores.h>
#include <thread>
#include <Common/config.h>
#if USE_CPUID
# include <libcpuid/libcpuid.h>
# include <Common/Exception.h>
namespace DB { namespace ErrorCodes { extern const int CPUID_ERROR; }}
#elif USE_CPUINFO
# include <cpuinfo.h>
#endif
unsigned getNumberOfPhysicalCPUCores()
{
#if USE_CPUID
cpu_raw_data_t raw_data;
if (0 != cpuid_get_raw_data(&raw_data))
throw DB::Exception("Cannot cpuid_get_raw_data: " + std::string(cpuid_error()), DB::ErrorCodes::CPUID_ERROR);
cpu_id_t data;
if (0 != cpu_identify(&raw_data, &data))
throw DB::Exception("Cannot cpu_identify: " + std::string(cpuid_error()), DB::ErrorCodes::CPUID_ERROR);
/// On Xen VMs, libcpuid returns wrong info (zero number of cores). Fallback to alternative method.
if (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();
}