commit 336affe9277fd0dee1d6bec028bb17f080a841af
Author: Campbell Barton <ideasman42@gmail.com>
Date:   Sun Oct 10 10:16:47 2021 +1100

    Support accessing the number of processors
    
    Add (processor-count) for accessing the number of cores/CPU's.

diff --git a/src/emacs.c b/src/emacs.c
index 866e43fda9..5715325ffe 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -3156,6 +3156,15 @@ DEFUN ("daemon-initialized", Fdaemon_initialized, Sdaemon_initialized, 0, 0, 0,
   return Qt;
 }
 
+DEFUN ("processor-count", Fprocessor_count, Sprocessor_count, 0, 0, 0,
+       doc: /* Return the number of processors on this system.
+
+The value will always be above zero, 1 for unsupported systems.  */)
+  (void)
+{
+  return make_fixnum (get_processor_count());
+}
+
 void
 syms_of_emacs (void)
 {
@@ -3176,6 +3185,7 @@ syms_of_emacs (void)
   defsubr (&Sinvocation_directory);
   defsubr (&Sdaemonp);
   defsubr (&Sdaemon_initialized);
+  defsubr (&Sprocessor_count);
 
   DEFVAR_LISP ("command-line-args", Vcommand_line_args,
 	       doc: /* Args passed by shell to Emacs, as a list of strings.
diff --git a/src/lisp.h b/src/lisp.h
index 480c389a3b..b74bcae7fb 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -4618,6 +4618,7 @@ maybe_disable_address_randomization (int argc, char **argv)
 extern EMACS_INT get_random (void);
 extern void seed_random (void *, ptrdiff_t);
 extern void init_random (void);
+extern int get_processor_count (void);
 extern void emacs_backtrace (int);
 extern AVOID emacs_abort (void) NO_INLINE;
 extern int emacs_fstatat (int, char const *, void *, int);
diff --git a/src/sysdep.c b/src/sysdep.c
index 8eaee22498..a46e3ce200 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -2182,6 +2182,38 @@ get_random (void)
   return val & INTMASK;
 }
 
+/*
+ * Return the number of CPU's / cores (>= 1).
+ */
+int
+get_processor_count (void)
+{
+  int nproc = -1;
+#ifdef WINDOWSNT
+  SYSTEM_INFO info;
+  GetSystemInfo(&info);
+  nproc = (int)info.dwNumberOfProcessors;
+#elif defined (HW_NCPUONLINE) || defined (HW_NCPU)
+  int mib[2];
+  size_t len;
+
+  mib[0] = CTL_HW;
+# ifdef HW_NCPUONLINE
+  mib[1] = HW_NCPUONLINE;
+# else
+  mib[1] = HW_NCPU;
+# endif
+  len = sizeof nproc;
+  sysctl(mib, 2, &nproc, &len, NULL, 0);
+#elif defined (__hpux)
+  nproc = mpctl(MPC_GETNUMSPUS, NULL, NULL);
+#elif defined (_SC_NPROCESSORS_ONLN)
+  nproc = (int)sysconf(_SC_NPROCESSORS_ONLN);
+#endif
+
+  return (nproc > 0) ? nproc : 1;
+}
+
 #ifndef HAVE_SNPRINTF
 /* Approximate snprintf as best we can on ancient hosts that lack it.  */
 int