1#
2# SYNOPSIS
3#
4#   TUKLIB_CPUCORES
5#
6# DESCRIPTION
7#
8#   Check how to find out the number of available CPU cores in the system.
9#   This information is used by tuklib_cpucores.c.
10#
11#   Supported methods:
12#     - GetSystemInfo(): Windows (including Cygwin)
13#     - sched_getaffinity(): glibc (GNU/Linux, GNU/kFreeBSD)
14#     - cpuset_getaffinity(): FreeBSD
15#     - sysctl(): BSDs, OS/2
16#     - sysconf(): GNU/Linux, Solaris, Tru64, IRIX, AIX, QNX, Cygwin (but
17#       GetSystemInfo() is used on Cygwin)
18#     - pstat_getdynamic(): HP-UX
19#
20# COPYING
21#
22#   Author: Lasse Collin
23#
24#   This file has been put into the public domain.
25#   You can do whatever you want with this file.
26#
27
28AC_DEFUN_ONCE([TUKLIB_CPUCORES], [
29AC_REQUIRE([TUKLIB_COMMON])
30
31# sys/param.h might be needed by sys/sysctl.h.
32AC_CHECK_HEADERS([sys/param.h])
33
34AC_CACHE_CHECK([how to detect the number of available CPU cores],
35	[tuklib_cv_cpucores_method], [
36
37# Maybe checking $host_os would be enough but this matches what
38# tuklib_cpucores.c does.
39#
40# NOTE: IRIX has a compiler that doesn't error out with #error, so use
41# a non-compilable text instead of #error to generate an error.
42AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
43#if defined(_WIN32) || defined(__CYGWIN__)
44int main(void) { return 0; }
45#else
46compile error
47#endif
48]])], [tuklib_cv_cpucores_method=special], [
49
50# glibc-based systems (GNU/Linux and GNU/kFreeBSD) have sched_getaffinity().
51# The CPU_COUNT() macro was added in glibc 2.9 so we try to link the
52# test program instead of merely compiling it. glibc 2.9 is old enough that
53# if someone uses the code on older glibc, the fallback to sysconf() should
54# be good enough.
55AC_LINK_IFELSE([AC_LANG_SOURCE([[
56#include <sched.h>
57int
58main(void)
59{
60	cpu_set_t cpu_mask;
61	sched_getaffinity(0, sizeof(cpu_mask), &cpu_mask);
62	return CPU_COUNT(&cpu_mask);
63}
64]])], [tuklib_cv_cpucores_method=sched_getaffinity], [
65
66# FreeBSD has both cpuset and sysctl. Look for cpuset first because
67# it's a better approach.
68#
69# This test would match on GNU/kFreeBSD too but it would require
70# -lfreebsd-glue when linking and thus in the current form this would
71# fail on GNU/kFreeBSD. The above test for sched_getaffinity() matches
72# on GNU/kFreeBSD so the test below should never run on that OS.
73AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
74#include <sys/param.h>
75#include <sys/cpuset.h>
76
77int
78main(void)
79{
80	cpuset_t set;
81	cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_PID, -1,
82			sizeof(set), &set);
83	return 0;
84}
85]])], [tuklib_cv_cpucores_method=cpuset], [
86
87# On OS/2, both sysconf() and sysctl() pass the tests in this file,
88# but only sysctl() works. On QNX it's the opposite: only sysconf() works
89# (although it assumes that _POSIX_SOURCE, _XOPEN_SOURCE, and _POSIX_C_SOURCE
90# are undefined or alternatively _QNX_SOURCE is defined).
91#
92# We test sysctl() first and intentionally break the sysctl() test on QNX
93# so that sysctl() is never used on QNX.
94AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
95#ifdef __QNX__
96compile error
97#endif
98#include <sys/types.h>
99#ifdef HAVE_SYS_PARAM_H
100#	include <sys/param.h>
101#endif
102#include <sys/sysctl.h>
103int
104main(void)
105{
106	int name[2] = { CTL_HW, HW_NCPU };
107	int cpus;
108	size_t cpus_size = sizeof(cpus);
109	sysctl(name, 2, &cpus, &cpus_size, NULL, 0);
110	return 0;
111}
112]])], [tuklib_cv_cpucores_method=sysctl], [
113
114AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
115#include <unistd.h>
116int
117main(void)
118{
119	long i;
120#ifdef _SC_NPROCESSORS_ONLN
121	/* Many systems using sysconf() */
122	i = sysconf(_SC_NPROCESSORS_ONLN);
123#else
124	/* IRIX */
125	i = sysconf(_SC_NPROC_ONLN);
126#endif
127	return 0;
128}
129]])], [tuklib_cv_cpucores_method=sysconf], [
130
131AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
132#include <sys/param.h>
133#include <sys/pstat.h>
134
135int
136main(void)
137{
138	struct pst_dynamic pst;
139	pstat_getdynamic(&pst, sizeof(pst), 1, 0);
140	(void)pst.psd_proc_cnt;
141	return 0;
142}
143]])], [tuklib_cv_cpucores_method=pstat_getdynamic], [
144
145	tuklib_cv_cpucores_method=unknown
146])])])])])])])
147
148case $tuklib_cv_cpucores_method in
149	sched_getaffinity)
150		AC_DEFINE([TUKLIB_CPUCORES_SCHED_GETAFFINITY], [1],
151			[Define to 1 if the number of available CPU cores
152			can be detected with sched_getaffinity()])
153		;;
154	cpuset)
155		AC_DEFINE([TUKLIB_CPUCORES_CPUSET], [1],
156			[Define to 1 if the number of available CPU cores
157			can be detected with cpuset(2).])
158		;;
159	sysctl)
160		AC_DEFINE([TUKLIB_CPUCORES_SYSCTL], [1],
161			[Define to 1 if the number of available CPU cores
162			can be detected with sysctl().])
163		;;
164	sysconf)
165		AC_DEFINE([TUKLIB_CPUCORES_SYSCONF], [1],
166			[Define to 1 if the number of available CPU cores
167			can be detected with sysconf(_SC_NPROCESSORS_ONLN)
168			or sysconf(_SC_NPROC_ONLN).])
169		;;
170	pstat_getdynamic)
171		AC_DEFINE([TUKLIB_CPUCORES_PSTAT_GETDYNAMIC], [1],
172			[Define to 1 if the number of available CPU cores
173			can be detected with pstat_getdynamic().])
174		;;
175esac
176])dnl
177