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diff src/os_cpu/solaris_sparc/vm/orderAccess_solaris_sparc.inline.hpp @ 1711:a6bff45449bc

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6973570: OrderAccess::storestore() scales poorly on multi-socket x64 and sparc: cache-line ping-ponging Summary: volatile store to static variable removed in favour of a volatile store to stack to avoid excessive cache coherency traffic; verified that the volatile store is not elided by any of our current compilers. Reviewed-by: dholmes, dice, jcoomes, kvn
author ysr
date Tue, 10 Aug 2010 14:53:35 -0700
parents c18cbe5936b8
children f95d63e2154a
line wrap: on
line diff
--- a/src/os_cpu/solaris_sparc/vm/orderAccess_solaris_sparc.inline.hpp	Mon Aug 09 18:03:50 2010 -0700
+++ b/src/os_cpu/solaris_sparc/vm/orderAccess_solaris_sparc.inline.hpp	Tue Aug 10 14:53:35 2010 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2009, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -42,8 +42,8 @@
 }
 
 inline void OrderAccess::release() {
-  jint* dummy = (jint*)&dummy;
-  __asm__ volatile("stw %%g0, [%0]" : : "r" (dummy) : "memory");
+  jint* local_dummy = (jint*)&local_dummy;
+  __asm__ volatile("stw %%g0, [%0]" : : "r" (local_dummy) : "memory");
 }
 
 inline void OrderAccess::fence() {
@@ -57,7 +57,9 @@
 }
 
 inline void OrderAccess::release() {
-  dummy = 0;
+  // Avoid hitting the same cache-line from
+  // different threads.
+  volatile jint local_dummy = 0;
 }
 
 inline void OrderAccess::fence() {