From: Russ Cox <rsc@golang.org>
Date: Wed, 9 Feb 2011 19:38:33 +0000 (-0500)
Subject: runtime: new allocation strategy for amd64
X-Git-Tag: weekly.2011-02-15~52
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=5b1b2ba9c79e54b3b34d066d43e88d1a4c330790;p=gostls13.git

runtime: new allocation strategy for amd64

Do not reserve virtual address space.
Instead, assume it will be there when we need it,
and crash loudly if that assumption is violated.
Reserving the address space gets charged to
ulimit -v, which exceeds commonly set limits.

http://groups.google.com/group/golang-dev/msg/7c477af5f5a8dd2c

R=r, niemeyer
CC=golang-dev
https://golang.org/cl/4148045
---

diff --git a/src/pkg/runtime/freebsd/mem.c b/src/pkg/runtime/freebsd/mem.c
index cbae187180..f5bbfa6fab 100644
--- a/src/pkg/runtime/freebsd/mem.c
+++ b/src/pkg/runtime/freebsd/mem.c
@@ -33,6 +33,12 @@ runtime·SysFree(void *v, uintptr n)
 void*
 runtime·SysReserve(void *v, uintptr n)
 {
+	// On 64-bit, people with ulimit -v set complain if we reserve too
+	// much address space.  Instead, assume that the reservation is okay
+	// and check the assumption in SysMap.
+	if(sizeof(void*) == 8)
+		return v;
+	
 	return runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
 }
 
@@ -42,6 +48,17 @@ runtime·SysMap(void *v, uintptr n)
 	void *p;
 	
 	mstats.sys += n;
+
+	// On 64-bit, we don't actually have v reserved, so tread carefully.
+	if(sizeof(void*) == 8) {
+		p = runtime·mmap(v, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, -1, 0);
+		if(p != v) {
+			runtime·printf("runtime: address space conflict: map(%v) = %v\n", v, p);
+			runtime·throw("runtime: address space conflict");
+		}
+		return;
+	}
+
 	p = runtime·mmap(v, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_FIXED|MAP_PRIVATE, -1, 0);
 	if(p != v)
 		runtime·throw("runtime: cannot map pages in arena address space");
diff --git a/src/pkg/runtime/linux/mem.c b/src/pkg/runtime/linux/mem.c
index 3a83e7394b..633ad0c62e 100644
--- a/src/pkg/runtime/linux/mem.c
+++ b/src/pkg/runtime/linux/mem.c
@@ -39,6 +39,12 @@ runtime·SysFree(void *v, uintptr n)
 void*
 runtime·SysReserve(void *v, uintptr n)
 {
+	// On 64-bit, people with ulimit -v set complain if we reserve too
+	// much address space.  Instead, assume that the reservation is okay
+	// and check the assumption in SysMap.
+	if(sizeof(void*) == 8)
+		return v;
+	
 	return runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
 }
 
@@ -48,6 +54,17 @@ runtime·SysMap(void *v, uintptr n)
 	void *p;
 	
 	mstats.sys += n;
+
+	// On 64-bit, we don't actually have v reserved, so tread carefully.
+	if(sizeof(void*) == 8) {
+		p = runtime·mmap(v, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, -1, 0);
+		if(p != v) {
+			runtime·printf("runtime: address space conflict: map(%v) = %v\n", v, p);
+			runtime·throw("runtime: address space conflict");
+		}
+		return;
+	}
+
 	p = runtime·mmap(v, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_FIXED|MAP_PRIVATE, -1, 0);
 	if(p != v)
 		runtime·throw("runtime: cannot map pages in arena address space");
diff --git a/test/run b/test/run
index ec01952535..28d0caa0f6 100755
--- a/test/run
+++ b/test/run
@@ -42,9 +42,7 @@ TMP2FILE=/tmp/gotest2-$$-$USER
 
 # don't run the machine out of memory: limit individual processes to 4GB.
 # on thresher, 3GB suffices to run the tests; with 2GB, peano fails.
-# Linux charges reserved but not mapped addresses to ulimit -v
-# so we have to use ulimit -m.
-ulimit -m 4000000
+ulimit -v 4000000
 
 # no core files please
 ulimit -c 0