ysr@777: /*
xdono@1014:  * Copyright 2001-2009 Sun Microsystems, Inc.  All Rights Reserved.
ysr@777:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
ysr@777:  *
ysr@777:  * This code is free software; you can redistribute it and/or modify it
ysr@777:  * under the terms of the GNU General Public License version 2 only, as
ysr@777:  * published by the Free Software Foundation.
ysr@777:  *
ysr@777:  * This code is distributed in the hope that it will be useful, but WITHOUT
ysr@777:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
ysr@777:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
ysr@777:  * version 2 for more details (a copy is included in the LICENSE file that
ysr@777:  * accompanied this code).
ysr@777:  *
ysr@777:  * You should have received a copy of the GNU General Public License version
ysr@777:  * 2 along with this work; if not, write to the Free Software Foundation,
ysr@777:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
ysr@777:  *
ysr@777:  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
ysr@777:  * CA 95054 USA or visit www.sun.com if you need additional information or
ysr@777:  * have any questions.
ysr@777:  *
ysr@777:  */
ysr@777: 
ysr@777: // Keeps track of the GC work and decides when it is OK to do GC work
ysr@777: // and for how long so that the MMU invariants are maintained.
ysr@777: 
ysr@777: /***** ALL TIMES ARE IN SECS!!!!!!! *****/
ysr@777: 
ysr@777: // this is the "interface"
apetrusenko@984: class G1MMUTracker: public CHeapObj {
ysr@777: protected:
ysr@777:   double          _time_slice;
ysr@777:   double          _max_gc_time; // this is per time slice
ysr@777: 
ysr@777: public:
ysr@777:   G1MMUTracker(double time_slice, double max_gc_time);
ysr@777: 
ysr@777:   virtual void add_pause(double start, double end, bool gc_thread) = 0;
ysr@777:   virtual double longest_pause(double current_time) = 0;
ysr@777:   virtual double when_sec(double current_time, double pause_time) = 0;
ysr@777: 
ysr@777:   double max_gc_time() {
tonyp@1371:     return _max_gc_time;
ysr@777:   }
ysr@777: 
ysr@777:   inline bool now_max_gc(double current_time) {
ysr@777:     return when_sec(current_time, max_gc_time()) < 0.00001;
ysr@777:   }
ysr@777: 
ysr@777:   inline double when_max_gc_sec(double current_time) {
ysr@777:     return when_sec(current_time, max_gc_time());
ysr@777:   }
ysr@777: 
ysr@777:   inline jlong when_max_gc_ms(double current_time) {
ysr@777:     double when = when_max_gc_sec(current_time);
ysr@777:     return (jlong) (when * 1000.0);
ysr@777:   }
ysr@777: 
ysr@777:   inline jlong when_ms(double current_time, double pause_time) {
ysr@777:     double when = when_sec(current_time, pause_time);
ysr@777:     return (jlong) (when * 1000.0);
ysr@777:   }
ysr@777: };
ysr@777: 
apetrusenko@984: class G1MMUTrackerQueueElem VALUE_OBJ_CLASS_SPEC {
ysr@777: private:
ysr@777:   double _start_time;
ysr@777:   double _end_time;
ysr@777: 
ysr@777: public:
ysr@777:   inline double start_time() { return _start_time; }
ysr@777:   inline double end_time()   { return _end_time; }
ysr@777:   inline double duration()   { return _end_time - _start_time; }
ysr@777: 
ysr@777:   G1MMUTrackerQueueElem() {
ysr@777:     _start_time = 0.0;
ysr@777:     _end_time   = 0.0;
ysr@777:   }
ysr@777: 
ysr@777:   G1MMUTrackerQueueElem(double start_time, double end_time) {
ysr@777:     _start_time = start_time;
ysr@777:     _end_time   = end_time;
ysr@777:   }
ysr@777: };
ysr@777: 
ysr@777: // this is an implementation of the MMUTracker using a (fixed-size) queue
ysr@777: // that keeps track of all the recent pause times
ysr@777: class G1MMUTrackerQueue: public G1MMUTracker {
ysr@777: private:
ysr@777:   enum PrivateConstants {
ysr@777:     QueueLength = 64
ysr@777:   };
ysr@777: 
ysr@777:   // The array keeps track of all the pauses that fall within a time
ysr@777:   // slice (the last time slice during which pauses took place).
ysr@777:   // The data structure implemented is a circular queue.
ysr@777:   // Head "points" to the most recent addition, tail to the oldest one.
ysr@777:   // The array is of fixed size and I don't think we'll need more than
ysr@777:   // two or three entries with the current behaviour of G1 pauses.
ysr@777:   // If the array is full, an easy fix is to look for the pauses with
ysr@1523:   // the shortest gap between them and consolidate them.
ysr@1523:   // For now, we have taken the expedient alternative of forgetting
tonyp@1717:   // the oldest entry in the event that +G1UseFixedWindowMMUTracker, thus
ysr@1523:   // potentially violating MMU specs for some time thereafter.
ysr@777: 
ysr@777:   G1MMUTrackerQueueElem _array[QueueLength];
ysr@777:   int                   _head_index;
ysr@777:   int                   _tail_index;
ysr@777:   int                   _no_entries;
ysr@777: 
ysr@777:   inline int trim_index(int index) {
ysr@777:     return (index + QueueLength) % QueueLength;
ysr@777:   }
ysr@777: 
ysr@777:   void remove_expired_entries(double current_time);
ysr@777:   double calculate_gc_time(double current_time);
ysr@777: 
ysr@777:   double longest_pause_internal(double current_time);
ysr@777:   double when_internal(double current_time, double pause_time);
ysr@777: 
ysr@777: public:
ysr@777:   G1MMUTrackerQueue(double time_slice, double max_gc_time);
ysr@777: 
ysr@777:   virtual void add_pause(double start, double end, bool gc_thread);
ysr@777: 
ysr@777:   virtual double longest_pause(double current_time);
ysr@777:   virtual double when_sec(double current_time, double pause_time);
ysr@777: };