8235931: add OM_CACHE_LINE_SIZE and use smaller size on SPARCv9 and X64

Reviewed-by: dholmes, redestad, mdoerr

src/hotspot/cpu/sparc/globalDefinitions_sparc.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2020, 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
@@ -42,12 +42,14 @@ const bool CCallingConventionRequiresIntsAsLongs = true;
 #if defined(TIERED)
   // tiered, 64-bit, large machine
   #define DEFAULT_CACHE_LINE_SIZE 128
+  #define OM_CACHE_LINE_SIZE 64
 #elif defined(COMPILER1)
   // pure C1, 32-bit, small machine
   #define DEFAULT_CACHE_LINE_SIZE 16
 #elif defined(COMPILER2)
   // pure C2, 64-bit, large machine
   #define DEFAULT_CACHE_LINE_SIZE 128
+  #define OM_CACHE_LINE_SIZE 64
 #endif
 
 #if defined(SOLARIS)

src/hotspot/cpu/x86/globalDefinitions_x86.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2020, 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
@@ -40,6 +40,7 @@ const bool CCallingConventionRequiresIntsAsLongs = false;
   #ifdef _LP64
     // tiered, 64-bit, large machine
     #define DEFAULT_CACHE_LINE_SIZE 128
+    #define OM_CACHE_LINE_SIZE 64
   #else
     // tiered, 32-bit, medium machine
     #define DEFAULT_CACHE_LINE_SIZE 64
@@ -52,6 +53,7 @@ const bool CCallingConventionRequiresIntsAsLongs = false;
   #ifdef _LP64
     // pure C2, 64-bit, large machine
     #define DEFAULT_CACHE_LINE_SIZE 128
+    #define OM_CACHE_LINE_SIZE 64
   #else
     // pure C2, 32-bit, medium machine
     #define DEFAULT_CACHE_LINE_SIZE 64

src/hotspot/share/runtime/objectMonitor.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2020, 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
@@ -120,6 +120,12 @@ class ObjectWaiter : public StackObj {
 //     intptr_t. There's no reason to use a 64-bit type for this field
 //     in a 64-bit JVM.
 
+#ifndef OM_CACHE_LINE_SIZE
+// Use DEFAULT_CACHE_LINE_SIZE if not already specified for
+// the current build platform.
+#define OM_CACHE_LINE_SIZE DEFAULT_CACHE_LINE_SIZE
+#endif
+
 class ObjectMonitor {
   friend class ObjectSynchronizer;
   friend class ObjectWaiter;
@@ -139,7 +145,7 @@ class ObjectMonitor {
   // _object is a good choice to share the cache line with _header.
   // _next_om shares _header's cache line for pre-monitor list historical
   // reasons. _next_om only changes if the next ObjectMonitor is deflated.
-  DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE,
+  DEFINE_PAD_MINUS_SIZE(0, OM_CACHE_LINE_SIZE,
                         sizeof(volatile markWord) + sizeof(void* volatile) +
                         sizeof(ObjectMonitor *));
   void* volatile _owner;            // pointer to owning thread OR BasicLock

src/hotspot/share/runtime/synchronizer.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2020, 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
@@ -517,15 +517,15 @@ void ObjectSynchronizer::notifyall(Handle obj, TRAPS) {
 // performed by the CPU(s) or platform.
 
 struct SharedGlobals {
-  char         _pad_prefix[DEFAULT_CACHE_LINE_SIZE];
+  char         _pad_prefix[OM_CACHE_LINE_SIZE];
   // These are highly shared mostly-read variables.
   // To avoid false-sharing they need to be the sole occupants of a cache line.
   volatile int stw_random;
   volatile int stw_cycle;
-  DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile int) * 2);
+  DEFINE_PAD_MINUS_SIZE(1, OM_CACHE_LINE_SIZE, sizeof(volatile int) * 2);
   // Hot RW variable -- Sequester to avoid false-sharing
   volatile int hc_sequence;
-  DEFINE_PAD_MINUS_SIZE(2, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile int));
+  DEFINE_PAD_MINUS_SIZE(2, OM_CACHE_LINE_SIZE, sizeof(volatile int));
 };
 
 static SharedGlobals GVars;
@@ -1082,9 +1082,9 @@ ObjectMonitor* ObjectSynchronizer::om_alloc(Thread* self) {
     assert(_BLOCKSIZE > 1, "invariant");
     size_t neededsize = sizeof(PaddedObjectMonitor) * _BLOCKSIZE;
     PaddedObjectMonitor* temp;
-    size_t aligned_size = neededsize + (DEFAULT_CACHE_LINE_SIZE - 1);
+    size_t aligned_size = neededsize + (OM_CACHE_LINE_SIZE - 1);
     void* real_malloc_addr = NEW_C_HEAP_ARRAY(char, aligned_size, mtInternal);
-    temp = (PaddedObjectMonitor*)align_up(real_malloc_addr, DEFAULT_CACHE_LINE_SIZE);
+    temp = (PaddedObjectMonitor*)align_up(real_malloc_addr, OM_CACHE_LINE_SIZE);
     (void)memset((void *) temp, 0, neededsize);
 
     // Format the block.

src/hotspot/share/runtime/synchronizer.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2020, 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
@@ -34,7 +34,13 @@
 class ObjectMonitor;
 class ThreadsList;
 
-typedef PaddedEnd<ObjectMonitor, DEFAULT_CACHE_LINE_SIZE> PaddedObjectMonitor;
+#ifndef OM_CACHE_LINE_SIZE
+// Use DEFAULT_CACHE_LINE_SIZE if not already specified for
+// the current build platform.
+#define OM_CACHE_LINE_SIZE DEFAULT_CACHE_LINE_SIZE
+#endif
+
+typedef PaddedEnd<ObjectMonitor, OM_CACHE_LINE_SIZE> PaddedObjectMonitor;
 
 struct DeflateMonitorCounters {
   int n_in_use;              // currently associated with objects