From b74d3e0c371a55cbd7aba7dc2c9f0001783aa231 Mon Sep 17 00:00:00 2001
From: Jason Evans <jasone@FreeBSD.org>
Date: Mon, 3 Nov 2008 21:17:18 +0000
Subject: Revert to preferring mmap(2) over sbrk(2) when mapping memory, due to
 potential extreme contention in the kernel for multi-threaded applications on
 SMP systems.

Reported by:	kris
---
 lib/libc/stdlib/malloc.c | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

(limited to 'lib/libc/stdlib/malloc.c')

diff --git a/lib/libc/stdlib/malloc.c b/lib/libc/stdlib/malloc.c
index 00b169fa12b3b..55bc4133a324d 100644
--- a/lib/libc/stdlib/malloc.c
+++ b/lib/libc/stdlib/malloc.c
@@ -1536,11 +1536,6 @@ base_pages_alloc(size_t minsize)
 {
 
 #ifdef MALLOC_DSS
-	if (opt_dss) {
-		if (base_pages_alloc_dss(minsize) == false)
-			return (false);
-	}
-
 	if (opt_mmap && minsize != 0)
 #endif
 	{
@@ -1548,6 +1543,14 @@ base_pages_alloc(size_t minsize)
 			return (false);
 	}
 
+#ifdef MALLOC_DSS
+	if (opt_dss) {
+		if (base_pages_alloc_dss(minsize) == false)
+			return (false);
+	}
+
+#endif
+
 	return (true);
 }
 
@@ -1983,6 +1986,15 @@ chunk_alloc(size_t size, bool zero)
 	assert(size != 0);
 	assert((size & chunksize_mask) == 0);
 
+#ifdef MALLOC_DSS
+	if (opt_mmap)
+#endif
+	{
+		ret = chunk_alloc_mmap(size);
+		if (ret != NULL)
+			goto RETURN;
+	}
+
 #ifdef MALLOC_DSS
 	if (opt_dss) {
 		ret = chunk_recycle_dss(size, zero);
@@ -1994,14 +2006,7 @@ chunk_alloc(size_t size, bool zero)
 		if (ret != NULL)
 			goto RETURN;
 	}
-
-	if (opt_mmap)
 #endif
-	{
-		ret = chunk_alloc_mmap(size);
-		if (ret != NULL)
-			goto RETURN;
-	}
 
 	/* All strategies for allocation failed. */
 	ret = NULL;
-- 
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