view src/share/vm/runtime/sweeper.hpp @ 1145:e018e6884bd8

6631166: CMS: better heuristics when combatting fragmentation Summary: Autonomic per-worker free block cache sizing, tunable coalition policies, fixes to per-size block statistics, retuned gain and bandwidth of some feedback loop filters to allow quicker reactivity to abrupt changes in ambient demand, and other heuristics to reduce fragmentation of the CMS old gen. Also tightened some assertions, including those related to locking. Reviewed-by: jmasa
author ysr
date Wed, 23 Dec 2009 09:23:54 -0800
parents a61af66fc99e
children 5f24d0319e54
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/*
 * Copyright 1997-2005 Sun Microsystems, Inc.  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.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 */

// An NmethodSweeper is an incremental cleaner for:
//    - cleanup inline caches
//    - reclamation of unreferences zombie nmethods
//

class NMethodSweeper : public AllStatic {
  static long      _traversals;   // Stack traversal count
  static CodeBlob* _current;      // Current nmethod
  static int       _seen;         // Nof. nmethod we have currently processed in current pass of CodeCache
  static int       _invocations;  // No. of invocations left until we are completed with this pass

  static bool      _rescan;          // Indicates that we should do a full rescan of the
                                     // of the code cache looking for work to do.
  static int       _locked_seen;     // Number of locked nmethods encountered during the scan
  static int       _not_entrant_seen_on_stack; // Number of not entrant nmethod were are still on stack


  static void process_nmethod(nmethod *nm);
 public:
  static long traversal_count() { return _traversals; }

  static void sweep();  // Invoked at the end of each safepoint

  static void notify(nmethod* nm) {
    // Perform a full scan of the code cache from the beginning.  No
    // need to synchronize the setting of this flag since it only
    // changes to false at safepoint so we can never overwrite it with false.
     _rescan = true;
  }
};