Use a /sys/devices/system/cpu/online for _SC_NPROCESSORS_ONLN implementation

diff --git a/ChangeLog b/ChangeLog
index 9cef65a..68409c9 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 2011-06-22  Ulrich Drepper  <drepper@gmail.com>
 
+       * sysdeps/unix/sysv/linux/getsysstats.c (__get_nprocs): Use
+       /sys/devices/system/cpu/online if it is usable.
+
        * sysdeps/unix/sysv/linux/getsysstats.c (__get_nprocs): Rate limit
        reading the information from the /proc filesystem to once a second.
 

diff --git a/sysdeps/unix/sysv/linux/getsysstats.c b/sysdeps/unix/sysv/linux/getsysstats.c
index a13b6e3..b74774f 100644 (file)
--- a/sysdeps/unix/sysv/linux/getsysstats.c
+++ b/sysdeps/unix/sysv/linux/getsysstats.c
@@ -161,20 +161,65 @@ __get_nprocs ()
   char *buffer_end = buffer + buffer_size;
   char *cp = buffer_end;
   char *re = buffer_end;
-  int result = 1;
 
 #ifdef O_CLOEXEC
   const int flags = O_RDONLY | O_CLOEXEC;
 #else
   const int flags = O_RDONLY;
 #endif
+  int fd = open_not_cancel_2 ("/sys/devices/system/cpu/online", flags);
+  char *l;
+  int result = 0;
+  if (fd != -1)
+    {
+      l = next_line (fd, buffer, &cp, &re, buffer_end);
+      if (l != NULL)
+       do
+         {
+           char *endp;
+           unsigned long int n = strtoul (l, &endp, 10);
+           if (l == endp)
+             {
+               result = 0;
+               break;
+             }
+
+           unsigned long int m = n;
+           if (*endp == '-')
+             {
+               l = endp + 1;
+               m = strtoul (l, &endp, 10);
+               if (l == endp)
+                 {
+                   result = 0;
+                   break;
+                 }
+             }
+
+           result += m - n + 1;
+
+           l = endp;
+           while (l < re && isspace (*l))
+             ++l;
+         }
+       while (l < re);
+
+      close_not_cancel_no_status (fd);
+
+      if (result > 0)
+       goto out;
+    }
+
+  cp = buffer_end;
+  re = buffer_end;
+  result = 1;
+
   /* The /proc/stat format is more uniform, use it by default.  */
-  int fd = open_not_cancel_2 ("/proc/stat", flags);
+  fd = open_not_cancel_2 ("/proc/stat", flags);
   if (fd != -1)
     {
       result = 0;
 
-      char *l;
       while ((l = next_line (fd, buffer, &cp, &re, buffer_end)) != NULL)
        /* The current format of /proc/stat has all the cpu* entries
           at the front.  We assume here that stays this way.  */
@@ -195,6 +240,7 @@ __get_nprocs ()
        }
     }
 
+ out:
   cached_result = result;
   atomic_write_barrier ();
   timestamp = ts.tv_sec;