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Kitware
GitHub Repository: Kitware/CMake
 Path: blob/master/Utilities/cmliblzma/common/tuklib_cpucores.c
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// SPDX-License-Identifier: 0BSD

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///////////////////////////////////////////////////////////////////////////////

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//

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/// \file       tuklib_cpucores.c

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/// \brief      Get the number of CPU cores online

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//

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//  Author:     Lasse Collin

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//

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///////////////////////////////////////////////////////////////////////////////

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#include "tuklib_cpucores.h"

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#if defined(_WIN32) || defined(__CYGWIN__)

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#	ifndef _WIN32_WINNT

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#		define _WIN32_WINNT 0x0500

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#	endif

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#	include <windows.h>

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// glibc >= 2.9

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#elif defined(TUKLIB_CPUCORES_SCHED_GETAFFINITY)

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#	include <sched.h>

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// FreeBSD

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#elif defined(TUKLIB_CPUCORES_CPUSET)

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#	include <sys/param.h>

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#	include <sys/cpuset.h>

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#elif defined(TUKLIB_CPUCORES_SYSCTL)

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#	ifdef HAVE_SYS_PARAM_H

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#		include <sys/param.h>

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#	endif

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#	include <sys/sysctl.h>

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#elif defined(TUKLIB_CPUCORES_SYSCONF)

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#	include <unistd.h>

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// HP-UX

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#elif defined(TUKLIB_CPUCORES_PSTAT_GETDYNAMIC)

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#	include <sys/param.h>

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#	include <sys/pstat.h>

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#endif

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extern uint32_t

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tuklib_cpucores(void)

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{

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	uint32_t ret = 0;

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#if defined(_WIN32) || defined(__CYGWIN__)

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	SYSTEM_INFO sysinfo;

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	GetSystemInfo(&sysinfo);

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	ret = sysinfo.dwNumberOfProcessors;

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#elif defined(TUKLIB_CPUCORES_SCHED_GETAFFINITY)

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	cpu_set_t cpu_mask;

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	if (sched_getaffinity(0, sizeof(cpu_mask), &cpu_mask) == 0)

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		ret = (uint32_t)CPU_COUNT(&cpu_mask);

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#elif defined(TUKLIB_CPUCORES_CPUSET)

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	cpuset_t set;

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	if (cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_PID, -1,

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			sizeof(set), &set) == 0) {

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#	ifdef CPU_COUNT

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		ret = (uint32_t)CPU_COUNT(&set);

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#	else

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		for (unsigned i = 0; i < CPU_SETSIZE; ++i)

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			if (CPU_ISSET(i, &set))

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				++ret;

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#	endif

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	}

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#elif defined(TUKLIB_CPUCORES_SYSCTL)

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	// On OpenBSD HW_NCPUONLINE tells the number of processor cores that

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	// are online so it is preferred over HW_NCPU which also counts cores

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	// that aren't currently available. The number of cores online is

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	// often less than HW_NCPU because OpenBSD disables simultaneous

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	// multi-threading (SMT) by default.

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#	ifdef HW_NCPUONLINE

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	int name[2] = { CTL_HW, HW_NCPUONLINE };

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#	else

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	int name[2] = { CTL_HW, HW_NCPU };

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#	endif

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	int cpus;

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	size_t cpus_size = sizeof(cpus);

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	if (sysctl(name, 2, &cpus, &cpus_size, NULL, 0) != -1

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			&& cpus_size == sizeof(cpus) && cpus > 0)

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		ret = (uint32_t)cpus;

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#elif defined(TUKLIB_CPUCORES_SYSCONF)

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#	ifdef _SC_NPROCESSORS_ONLN

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	// Most systems

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	const long cpus = sysconf(_SC_NPROCESSORS_ONLN);

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#	else

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	// IRIX

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	const long cpus = sysconf(_SC_NPROC_ONLN);

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#	endif

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	if (cpus > 0)

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		ret = (uint32_t)cpus;

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#elif defined(TUKLIB_CPUCORES_PSTAT_GETDYNAMIC)

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	struct pst_dynamic pst;

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	if (pstat_getdynamic(&pst, sizeof(pst), 1, 0) != -1)

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		ret = (uint32_t)pst.psd_proc_cnt;

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#endif

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	return ret;

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}

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