kosaki	2014-10-22 03:46:33 +0900 (Wed, 22 Oct 2014)

  New Revision: 48080

  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=48080

  Log:
    * ext/etc/etc.c (etc_nprocessors_affin): optimize memory usege a
      bit. Typical rubyist never use 8k cpus machine.

  Modified files:
    trunk/ChangeLog
    trunk/ext/etc/etc.c
Index: ChangeLog
===================================================================
--- ChangeLog	(revision 48079)
+++ ChangeLog	(revision 48080)
@@ -1,3 +1,8 @@ https://github.com/ruby/ruby/blob/trunk/ChangeLog#L1
+Wed Oct 22 03:33:58 2014  KOSAKI Motohiro  <kosaki.motohiro@g...>
+
+	* ext/etc/etc.c (etc_nprocessors_affin): optimize memory usege a
+	  bit. Typical rubyist never use 8k cpus machine.
+
 Wed Oct 22 00:01:09 2014  Yuki Yugui Sonoda  <yugui@y...>
 
 	* configure.in (XCFLAGS): Add include path for NaCl libraries.
Index: ext/etc/etc.c
===================================================================
--- ext/etc/etc.c	(revision 48079)
+++ ext/etc/etc.c	(revision 48080)
@@ -916,7 +916,7 @@ etc_nprocessors_affin(void) https://github.com/ruby/ruby/blob/trunk/ext/etc/etc.c#L916
     cpu_set_t *cpuset;
     size_t size;
     int ret;
-    int ncpus;
+    int n;
 
     /*
      * XXX:
@@ -934,24 +934,31 @@ etc_nprocessors_affin(void) https://github.com/ruby/ruby/blob/trunk/ext/etc/etc.c#L934
      * So, we use hardcode number for workaround. Current linux kernel
      * (Linux 3.17) support 8192 cpus at maximum. Then 16384 is enough large.
      */
-    ncpus = 16384;
+    for (n=64; n < 16384; n *= 2) {
+	size = CPU_ALLOC_SIZE(n);
+	if (size >= 1024) {
+	    cpuset = xcalloc(1, size);
+	    if (!cpuset)
+		return -1;
+	} else {
+	    cpuset = alloca(size);
+	    CPU_ZERO_S(size, cpuset);
+	}
 
-    cpuset = CPU_ALLOC(ncpus);
-    if (!cpuset) {
-       return -1;
-    }
-    size = CPU_ALLOC_SIZE(ncpus);
-    CPU_ZERO_S(size, cpuset);
+	ret = sched_getaffinity(0, size, cpuset);
+	if (ret == 0) {
+	    /* On success, count number of cpus. */
+	    ret = CPU_COUNT_S(size, cpuset);
+	}
 
-    ret = sched_getaffinity(0, size, cpuset);
-    if (ret==-1) {
-       goto free;
+	if (size >= 1024) {
+	    xfree(cpuset);
+	}
+	if (ret > 0) {
+	    return ret;
+	}
     }
 
-    ret = CPU_COUNT_S(size, cpuset);
-  free:
-    CPU_FREE(cpuset);
-
     return ret;
 }
 #endif

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