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changeset 4298:9def4075da6d

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8008079: G1: Add nextObject routine to CMBitMapRO and replace nextWord Summary: Update the task local finger to the start of the next object when marking aborts, in order to avoid the redundant scanning of all 0's when the marking task restarts, if otherwise updating to the next word. In addition, reuse the routine nextObject() in routine iterate(). Reviewed-by: johnc, ysr Contributed-by: tamao <tao.mao@oracle.com>
author tamao
date Tue, 05 Mar 2013 15:36:56 -0800
parents d778bb46a9a5
children 209f8ba5020b
files src/share/vm/gc_implementation/g1/concurrentMark.cpp src/share/vm/gc_implementation/g1/concurrentMark.hpp src/share/vm/gc_implementation/g1/concurrentMark.inline.hpp
diffstat 3 files changed, 10 insertions(+), 8 deletions(-) [+]
line wrap: on
line diff
--- a/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Mon Mar 04 22:39:00 2013 -0800
+++ b/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Tue Mar 05 15:36:56 2013 -0800
@@ -4111,7 +4111,7 @@
         // bitmap knows by how much we need to move it as it knows its
         // granularity).
         assert(_finger < _region_limit, "invariant");
-        HeapWord* new_finger = _nextMarkBitMap->nextWord(_finger);
+        HeapWord* new_finger = _nextMarkBitMap->nextObject(_finger);
         // Check if bitmap iteration was aborted while scanning the last object
         if (new_finger >= _region_limit) {
           giveup_current_region();
--- a/src/share/vm/gc_implementation/g1/concurrentMark.hpp	Mon Mar 04 22:39:00 2013 -0800
+++ b/src/share/vm/gc_implementation/g1/concurrentMark.hpp	Tue Mar 05 15:36:56 2013 -0800
@@ -97,7 +97,6 @@
                                        HeapWord* limit = NULL) const;
 
   // conversion utilities
-  // XXX Fix these so that offsets are size_t's...
   HeapWord* offsetToHeapWord(size_t offset) const {
     return _bmStartWord + (offset << _shifter);
   }
@@ -105,8 +104,13 @@
     return pointer_delta(addr, _bmStartWord) >> _shifter;
   }
   int heapWordDiffToOffsetDiff(size_t diff) const;
-  HeapWord* nextWord(HeapWord* addr) {
-    return offsetToHeapWord(heapWordToOffset(addr) + 1);
+
+  // The argument addr should be the start address of a valid object
+  HeapWord* nextObject(HeapWord* addr) {
+    oop obj = (oop) addr;
+    HeapWord* res =  addr + obj->size();
+    assert(offsetToHeapWord(heapWordToOffset(res)) == res, "sanity");
+    return res;
   }
 
   // debugging
--- a/src/share/vm/gc_implementation/g1/concurrentMark.inline.hpp	Mon Mar 04 22:39:00 2013 -0800
+++ b/src/share/vm/gc_implementation/g1/concurrentMark.inline.hpp	Tue Mar 05 15:36:56 2013 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2013, 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
@@ -252,12 +252,10 @@
 
     start_offset = _bm.get_next_one_offset(start_offset, end_offset);
     while (start_offset < end_offset) {
-      HeapWord* obj_addr = offsetToHeapWord(start_offset);
-      oop obj = (oop) obj_addr;
       if (!cl->do_bit(start_offset)) {
         return false;
       }
-      HeapWord* next_addr = MIN2(obj_addr + obj->size(), end_addr);
+      HeapWord* next_addr = MIN2(nextObject(offsetToHeapWord(start_offset)), end_addr);
       BitMap::idx_t next_offset = heapWordToOffset(next_addr);
       start_offset = _bm.get_next_one_offset(next_offset, end_offset);
     }