Hi,
Giuseppe Scrivano wrote:
> On BSDs, where SC_NPROCESSORS_ONLN is not available, the number of
> online processors can be retrieved using `sysctl'.
>
> From 73c11226e320c1144887daeb15e3f549b0bb2ee5 Mon Sep 17 00:00:00 2001
> From: Giuseppe Scrivano <gscriv...@gnu.org>
> Date: Sun, 18 Oct 2009 01:20:14 +0200
> Subject: [PATCH] nproc: use `sysctl' when it is available.
>
> * lib/nproc.c (num_processors): If `sysctl' is available, use it to
> get the number of online processors.
> ---
> lib/nproc.c | 10 ++++++++++
> 1 files changed, 10 insertions(+), 0 deletions(-)
>
> diff --git a/lib/nproc.c b/lib/nproc.c
> index 9a6e23a..f45feaf 100644
> --- a/lib/nproc.c
> +++ b/lib/nproc.c
> @@ -34,5 +34,15 @@ num_processors (void)
> return nprocs;
> #endif
>
> +#ifdef HW_NCPU
> + int ret;
> + int mib[2] = {CTL_HW, HW_NCPU};
> + long int nprocs;
> + size_t len = sizeof (nprocs);
> + ret = sysctl (mib, 2, &nprocs, &len, NULL, 0);
> + if (ret == 0)
> + return nprocs;
> +#endif
> +
> return 1;
> }
Thanks for the patch. It has a number of problems:
- It is a nop, because HW_NCPU is defined in <sys/sysctl.h>, but this
header file is not included. (Did you try "nm nproc.o"?)
- The nprocs variable must be an 'int', not 'long int'. That's how it's
documented in the sys/sysctl.h, and that's also what MacOS X 10.5 in 64-bit
mode requires.
- The function is documented to guarantee a positive return value. This is
not ensured here.
- On platforms which have both the sysconf approach and HW_NCPU, your patch
introduces declarations after statements, which is does not work with ANSI C
compilers.
But these can all be fixed. I'm applying the patch below.
2009-10-18 Giuseppe Scrivano <gscriv...@gnu.org>
Bruno Haible <br...@clisp.org>
Implement nproc for NetBSD, OpenBSD.
* lib/nproc.c: Include <sys/types.h>, <sys/param.h>, <sys/sysctl.h>.
(ARRAY_SIZE): New macro.
(num_processors): On BSD systems, try sysctl of HW_NCPU.
* m4/nproc.m4: New file.
* modules/nproc (Files): Add m4/nproc.m4.
(configure.ac): Invoke gl_NPROC. Remove AC_LIBOBJ invocation.
(Makefile.am): Instead, augment lib_SOURCES.
--- lib/nproc.c.orig 2009-10-18 10:08:29.000000000 +0200
+++ lib/nproc.c 2009-10-18 10:07:34.000000000 +0200
@@ -23,15 +23,43 @@
#include <unistd.h>
+#include <sys/types.h>
+
+#if HAVE_SYS_PARAM_H
+# include <sys/param.h>
+#endif
+
+#if HAVE_SYS_SYSCTL_H
+# include <sys/sysctl.h>
+#endif
+
+#define ARRAY_SIZE(a) (sizeof (a) / sizeof ((a)[0]))
+
/* Return the total number of processors. The result is guaranteed to
be at least 1. */
unsigned long int
num_processors (void)
{
-#ifdef _SC_NPROCESSORS_ONLN
- long int nprocs = sysconf (_SC_NPROCESSORS_ONLN);
- if (0 < nprocs)
- return nprocs;
+#if defined _SC_NPROCESSORS_ONLN
+ { /* This works on glibc, MacOS X 10.5, FreeBSD, AIX, OSF/1, Solaris, Cygwin,
+ Haiku. */
+ long int nprocs = sysconf (_SC_NPROCESSORS_ONLN);
+ if (0 < nprocs)
+ return nprocs;
+ }
+#endif
+
+#if HAVE_SYSCTL && defined HW_NCPU
+ { /* This works on MacOS X, FreeBSD, NetBSD, OpenBSD. */
+ int nprocs;
+ size_t len = sizeof (nprocs);
+ static int mib[2] = { CTL_HW, HW_NCPU };
+
+ if (sysctl (mib, ARRAY_SIZE (mib), &nprocs, &len, NULL, 0) == 0
+ && len == sizeof (nprocs)
+ && 0 < nprocs)
+ return nprocs;
+ }
#endif
return 1;
--- modules/nproc.orig 2009-10-18 10:08:29.000000000 +0200
+++ modules/nproc 2009-10-18 09:33:19.000000000 +0200
@@ -4,14 +4,16 @@
Files:
lib/nproc.h
lib/nproc.c
+m4/nproc.m4
Depends-on:
unistd
configure.ac:
-AC_LIBOBJ([nproc])
+gl_NPROC
Makefile.am:
+lib_SOURCES += nproc.c
Include:
"nproc.h"
================================= m4/nproc.m4 =================================
# nproc.m4 serial 1
dnl Copyright (C) 2009 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
AC_DEFUN([gl_NPROC],
[
gl_PREREQ_NPROC
])
# Prerequisites of lib/nproc.c.
AC_DEFUN([gl_PREREQ_NPROC],
[
AC_CHECK_HEADERS([sys/param.h],,, [AC_INCLUDES_DEFAULT])
dnl <sys/sysctl.h> requires <sys/param.h> on OpenBSD 4.0.
AC_CHECK_HEADERS([sys/sysctl.h],,,
[AC_INCLUDES_DEFAULT
#if HAVE_SYS_PARAM_H
# include <sys/param.h>
#endif
])
AC_CHECK_FUNCS([sysctl])
])
