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Re: implementation of std::thread::hardware_concurrency()
This provides a working thread::hardware_concurrency on platforms that
support pthread_num_processors_np or the "hw.ncpu" sysctl, but by
testing for the features in configure rather than hardcoding OS macro
tests in thread.cc
* acinclude.m4 (GLIBCXX_CHECK_SC_NPROC_ONLN): Define.
(GLIBCXX_CHECK_PTHREADS_NUM_PROCESSORS_NP): Define.
(GLIBCXX_CHECK_SYSCTL_HW_NCPU): Define.
* configure.ac: Use new checks.
* configure: Regenerate.
* config.h.in: Regenerate.
* src/thread.cc: Check new config macros.
* testsuite/lib/libstdc++.exp: Likewise.
Tested x86_64-linux and x86_64-netbsd5.1, committed to trunk
Index: acinclude.m4
===================================================================
--- acinclude.m4 (revision 181081)
+++ acinclude.m4 (working copy)
@@ -3459,7 +3459,95 @@
AC_LANG_RESTORE
])
+dnl
+dnl Check whether sysconf(_SC_NPROC_ONLN) is available in <unistd.h>, and define _GLIBCXX_USE_SC_NPROC_ONLN.
+dnl
+AC_DEFUN([GLIBCXX_CHECK_SC_NPROC_ONLN], [
+ AC_LANG_SAVE
+ AC_LANG_CPLUSPLUS
+ ac_save_CXXFLAGS="$CXXFLAGS"
+ CXXFLAGS="$CXXFLAGS -fno-exceptions"
+
+ AC_MSG_CHECKING([for _SC_NPROC_ONLN])
+ AC_CACHE_VAL(glibcxx_cv_SC_NPROC_ONLN, [
+ GCC_TRY_COMPILE_OR_LINK(
+ [#include <unistd.h>],
+ [int n = sysconf(_SC_NPROC_ONLN);],
+ [glibcxx_cv_SC_NPROC_ONLN=yes],
+ [glibcxx_cv_SC_NPROC_ONLN=no])
+ ])
+ if test $glibcxx_cv_SC_NPROC_ONLN = yes; then
+ AC_DEFINE(_GLIBCXX_USE_SC_NPROC_ONLN, 1, [Define if _SC_NPROC_ONLN is available in <unistd.h>.])
+ fi
+ AC_MSG_RESULT($glibcxx_cv_SC_NPROC_ONLN)
+
+ CXXFLAGS="$ac_save_CXXFLAGS"
+ AC_LANG_RESTORE
+])
+
+dnl
+dnl Check whether pthread_num_processors_np is available in <pthread.h>, and define _GLIBCXX_USE_PTHREADS_NUM_PROCESSORS_NP.
+dnl
+AC_DEFUN([GLIBCXX_CHECK_PTHREADS_NUM_PROCESSORS_NP], [
+
+ AC_LANG_SAVE
+ AC_LANG_CPLUSPLUS
+ ac_save_CXXFLAGS="$CXXFLAGS"
+ CXXFLAGS="$CXXFLAGS -fno-exceptions"
+
+ AC_MSG_CHECKING([for pthreads_num_processors_np])
+ AC_CACHE_VAL(glibcxx_cv_PTHREADS_NUM_PROCESSORS_NP, [
+ GCC_TRY_COMPILE_OR_LINK(
+ [#include <pthread.h>],
+ [int n = pthread_num_processors_np();],
+ [glibcxx_cv_PTHREADS_NUM_PROCESSORS_NP=yes],
+ [glibcxx_cv_PTHREADS_NUM_PROCESSORS_NP=no])
+ ])
+ if test $glibcxx_cv_PTHREADS_NUM_PROCESSORS_NP = yes; then
+ AC_DEFINE(_GLIBCXX_USE_PTHREADS_NUM_PROCESSORS_NP, 1, [Define if pthreads_num_processors_np is available in <pthread.h>.])
+ fi
+ AC_MSG_RESULT($glibcxx_cv_PTHREADS_NUM_PROCESSORS_NP)
+
+ CXXFLAGS="$ac_save_CXXFLAGS"
+ AC_LANG_RESTORE
+])
+
+dnl
+dnl Check whether sysctl is available in <pthread.h>, and define _GLIBCXX_USE_SYSCTL_HW_NCPU.
+dnl
+AC_DEFUN([GLIBCXX_CHECK_SYSCTL_HW_NCPU], [
+
+ AC_LANG_SAVE
+ AC_LANG_CPLUSPLUS
+ ac_save_CXXFLAGS="$CXXFLAGS"
+ CXXFLAGS="$CXXFLAGS -fno-exceptions"
+
+ AC_MSG_CHECKING([for hw.ncpu sysctl])
+ AC_CACHE_VAL(glibcxx_cv_SYSCTL_HW_NCPU, [
+ GCC_TRY_COMPILE_OR_LINK(
+ [
+ #include <stddef.h>
+ #include <sys/sysctl.h>
+ ],
+ [
+ int count;
+ size_t size = sizeof(count);
+ int mib[] = { CTL_HW, HW_NCPU };
+ sysctl(mib, 2, &count, &size, NULL, 0);
+ ],
+ [glibcxx_cv_SYSCTL_HW_NCPU=yes],
+ [glibcxx_cv_SYSCTL_HW_NCPU=no])
+ ])
+ if test $glibcxx_cv_SYSCTL_HW_NCPU = yes; then
+ AC_DEFINE(_GLIBCXX_USE_SYSCTL_HW_NCPU, 1, [Define if sysctl(), CTL_HW and HW_NCPU are available in <sys/sysctl.h>.])
+ fi
+ AC_MSG_RESULT($glibcxx_cv_SYSCTL_HW_NCPU)
+
+ CXXFLAGS="$ac_save_CXXFLAGS"
+ AC_LANG_RESTORE
+])
+
# Macros from the top-level gcc directory.
m4_include([../config/gc++filt.m4])
m4_include([../config/tls.m4])
Index: configure.ac
===================================================================
--- configure.ac (revision 181081)
+++ configure.ac (working copy)
@@ -174,6 +174,9 @@
GLIBCXX_CHECK_GET_NPROCS
AC_CHECK_HEADERS(unistd.h)
GLIBCXX_CHECK_SC_NPROCESSORS_ONLN
+GLIBCXX_CHECK_SC_NPROC_ONLN
+GLIBCXX_CHECK_PTHREADS_NUM_PROCESSORS_NP
+GLIBCXX_CHECK_SYSCTL_HW_NCPU
# Check for available headers.
AC_CHECK_HEADERS([endian.h execinfo.h float.h fp.h ieeefp.h inttypes.h \
Index: src/thread.cc
===================================================================
--- src/thread.cc (revision 181081)
+++ src/thread.cc (working copy)
@@ -30,9 +30,27 @@
#if defined(_GLIBCXX_USE_GET_NPROCS)
# include <sys/sysinfo.h>
# define _GLIBCXX_NPROCS get_nprocs()
+#elif defined(_GLIBCXX_USE_PTHREADS_NUM_PROCESSORS_NP)
+# define _GLIBCXX_NPROCS pthread_num_processors_np()
+#elif defined(_GLIBCXX_USE_SYSCTL_HW_NCPU)
+# include <stddef.h>
+# include <sys/sysctl.h>
+static inline int get_nprocs()
+{
+ int count;
+ size_t size = sizeof(count);
+ int mib[] = { CTL_HW, HW_NCPU };
+ if (!sysctl(mib, 2, &count, &size, NULL, 0))
+ return count;
+ return 0;
+}
+# define _GLIBCXX_NPROCS get_nprocs()
#elif defined(_GLIBCXX_USE_SC_NPROCESSORS_ONLN)
# include <unistd.h>
# define _GLIBCXX_NPROCS sysconf(_SC_NPROCESSORS_ONLN)
+#elif defined(_GLIBCXX_USE_SC_NPROC_ONLN)
+# include <unistd.h>
+# define _GLIBCXX_NPROCS sysconf(_SC_NPROC_ONLN)
#else
# define _GLIBCXX_NPROCS 0
#endif
Index: testsuite/lib/libstdc++.exp
===================================================================
--- testsuite/lib/libstdc++.exp (revision 181081)
+++ testsuite/lib/libstdc++.exp (working copy)
@@ -1673,13 +1673,12 @@
set f [open $src "w"]
puts $f "#include <bits/c++config.h>"
puts $f "#if defined(_GLIBCXX_USE_GET_NPROCS)"
- puts $f "#elif defined(_GLIBCXX_USE_SYSCONF)"
- puts $f "# include <unistd.h>"
- puts $f "# if !defined(_SC_NPROCESSORS_ONLN)"
- puts $f "# error No sysconf option"
- puts $f "# endif"
+ puts $f "#elif defined(_GLIBCXX_USE_PTHREADS_NUM_PROCESSORS_NP)"
+ puts $f "#elif defined(_GLIBCXX_USE_SYSCTL_HW_NCPU)"
+ puts $f "#elif defined(_GLIBCXX_USE_SC_NPROCESSORS_ONLN)"
+ puts $f "#elif defined(_GLIBCXX_USE_SC_NPROC_ONLN)"
puts $f "#else"
- puts $f "# error No get_nprocs or sysconf"
+ puts $f "# error hardware_concurrency not implemented"
puts $f "#endif"
close $f