From 0fa75e813ecf0f5f3dd01f89aa76d0e25ab4fcd4 Mon Sep 17 00:00:00 2001
From: kosaki <kosaki@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Tue, 21 Oct 2014 18:46:33 +0000
Subject: [PATCH] * ext/etc/etc.c (etc_nprocessors_affin): optimize memory
 usege a   bit. Typical rubyist never use 8k cpus machine.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48080 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 ChangeLog     |  5 +++++
 ext/etc/etc.c | 39 +++++++++++++++++++++++----------------
 2 files changed, 28 insertions(+), 16 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index a24010b039..da148ec1a1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Oct 22 03:33:58 2014  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* 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@yugui.jp>
 
 	* configure.in (XCFLAGS): Add include path for NaCl libraries.
diff --git a/ext/etc/etc.c b/ext/etc/etc.c
index a37d77cef6..58c00b0161 100644
--- a/ext/etc/etc.c
+++ b/ext/etc/etc.c
@@ -916,7 +916,7 @@ etc_nprocessors_affin(void)
     cpu_set_t *cpuset;
     size_t size;
     int ret;
-    int ncpus;
+    int n;
 
     /*
      * XXX:
@@ -934,23 +934,30 @@ etc_nprocessors_affin(void)
      * 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;
+	ret = sched_getaffinity(0, size, cpuset);
+	if (ret == 0) {
+	    /* On success, count number of cpus. */
+	    ret = CPU_COUNT_S(size, cpuset);
+	}
+
+	if (size >= 1024) {
+	    xfree(cpuset);
+	}
+	if (ret > 0) {
+	    return ret;
+	}
     }
-    size = CPU_ALLOC_SIZE(ncpus);
-    CPU_ZERO_S(size, cpuset);
-
-    ret = sched_getaffinity(0, size, cpuset);
-    if (ret==-1) {
-       goto free;
-    }
-
-    ret = CPU_COUNT_S(size, cpuset);
-  free:
-    CPU_FREE(cpuset);
 
     return ret;
 }