src/share/vm/gc/g1/g1FromCardCache.hpp

rev 10669 : [mq]: 8148099-transpose-fcc

*** 1,7 ****
  /*
!  * Copyright (c) 2013, 2015, 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) 2013, 2016, 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.
*** 30,41 ****
  
  // G1FromCardCache remembers the most recently processed card on the heap on
  // a per-region and per-thread basis.
  class G1FromCardCache : public AllStatic {
   private:
!   // Array of card indices. Indexed by thread X and heap region to minimize
    // thread contention.
    static int** _cache;
    static uint _max_regions;
    static size_t _static_mem_size;
  
   public:
--- 30,44 ----
  
  // G1FromCardCache remembers the most recently processed card on the heap on
  // a per-region and per-thread basis.
  class G1FromCardCache : public AllStatic {
   private:
!   // Array of card indices. Indexed by heap region (rows) and thread (columns) to minimize
    // thread contention.
+   // This order minimizes the time to clear all entries for a given region during region
+   // freeing. I.e. a single clear of a single memory area instead of multiple separate
+   // accesses with a large stride per region.
    static int** _cache;
    static uint _max_regions;
    static size_t _static_mem_size;
  
   public:
*** 56,70 ****
        return false;
      }
    }
  
    static int at(uint worker_id, uint region_idx) {
!     return _cache[worker_id][region_idx];
    }
  
    static void set(uint worker_id, uint region_idx, int val) {
!     _cache[worker_id][region_idx] = val;
    }
  
    static void initialize(uint num_par_rem_sets, uint max_num_regions);
  
    static void invalidate(uint start_idx, size_t num_regions);
--- 59,73 ----
        return false;
      }
    }
  
    static int at(uint worker_id, uint region_idx) {
!     return _cache[region_idx][worker_id];
    }
  
    static void set(uint worker_id, uint region_idx, int val) {
!     _cache[region_idx][worker_id] = val;
    }
  
    static void initialize(uint num_par_rem_sets, uint max_num_regions);
  
    static void invalidate(uint start_idx, size_t num_regions);