src/share/vm/memory/cardTableRS.cpp

*** 1,7 ****
  /*
!  * Copyright (c) 2001, 2011, 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
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
--- 1,7 ----
  /*
!  * Copyright (c) 2001, 2012, 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
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
*** 171,180 ****
--- 171,184 ----
      assert(!_is_par ||
             (SharedHeap::heap()->n_par_threads() ==
              SharedHeap::heap()->workers()->active_workers()), "Mismatch");
  }
  
+ bool ClearNoncleanCardWrapper::is_word_aligned(jbyte* entry) {
+   return (((intptr_t)entry) & (BytesPerWord-1)) == 0;
+ }
+ 
  void ClearNoncleanCardWrapper::do_MemRegion(MemRegion mr) {
    assert(mr.word_size() > 0, "Error");
    assert(_ct->is_aligned(mr.start()), "mr.start() should be card aligned");
    // mr.end() may not necessarily be card aligned.
    jbyte* cur_entry = _ct->byte_for(mr.last());
*** 185,213 ****
      HeapWord* cur_hw = _ct->addr_for(cur_entry);
      if ((*cur_entry != CardTableRS::clean_card_val()) && clear_card(cur_entry)) {
        // Continue the dirty range by opening the
        // dirty window one card to the left.
        start_of_non_clean = cur_hw;
      } else {
        // We hit a "clean" card; process any non-empty
        // "dirty" range accumulated so far.
        if (start_of_non_clean < end_of_non_clean) {
          const MemRegion mrd(start_of_non_clean, end_of_non_clean);
          _dirty_card_closure->do_MemRegion(mrd);
        }
        // Reset the dirty window, while continuing to look
        // for the next dirty card that will start a
        // new dirty window.
        end_of_non_clean = cur_hw;
        start_of_non_clean = cur_hw;
      }
      // Note that "cur_entry" leads "start_of_non_clean" in
      // its leftward excursion after this point
      // in the loop and, when we hit the left end of "mr",
      // will point off of the left end of the card-table
      // for "mr".
-     cur_entry--;
    }
    // If the first card of "mr" was dirty, we will have
    // been left with a dirty window, co-initial with "mr",
    // which we now process.
    if (start_of_non_clean < end_of_non_clean) {
--- 189,237 ----
      HeapWord* cur_hw = _ct->addr_for(cur_entry);
      if ((*cur_entry != CardTableRS::clean_card_val()) && clear_card(cur_entry)) {
        // Continue the dirty range by opening the
        // dirty window one card to the left.
        start_of_non_clean = cur_hw;
+ 
+       cur_entry--;
      } else {
        // We hit a "clean" card; process any non-empty
        // "dirty" range accumulated so far.
        if (start_of_non_clean < end_of_non_clean) {
          const MemRegion mrd(start_of_non_clean, end_of_non_clean);
          _dirty_card_closure->do_MemRegion(mrd);
        }
+ 
+       // fast forward through potential continuous range of clean cards
+       if (is_word_aligned(cur_entry)) {
+         jbyte* cur_row = cur_entry - BytesPerWord;
+         while(cur_row >= limit) {
+           if (*((intptr_t*)cur_row) ==  CardTableRS::clean_card_row()) {
+                 cur_row -= BytesPerWord;
+             }
+             else {
+                 break;
+             }
+         }
+         cur_entry = cur_row + (BytesPerWord - 1);
+         HeapWord* last_hw = _ct->addr_for(cur_row + BytesPerWord);
+         end_of_non_clean = last_hw;
+         start_of_non_clean = last_hw;
+       } else {
            // Reset the dirty window, while continuing to look
            // for the next dirty card that will start a
            // new dirty window.
            end_of_non_clean = cur_hw;
            start_of_non_clean = cur_hw;
+           cur_entry--;
+       }
      }
      // Note that "cur_entry" leads "start_of_non_clean" in
      // its leftward excursion after this point
      // in the loop and, when we hit the left end of "mr",
      // will point off of the left end of the card-table
      // for "mr".
    }
    // If the first card of "mr" was dirty, we will have
    // been left with a dirty window, co-initial with "mr",
    // which we now process.
    if (start_of_non_clean < end_of_non_clean) {