--- a/hotspot/src/share/vm/gc_implementation/shared/coTracker.hpp Mon Aug 24 10:36:31 2009 -0700
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,181 +0,0 @@
-/*
- * Copyright 2001-2007 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.
- *
- */
-
-// COTracker keeps track of the concurrent overhead of a GC thread.
-
-// A thread that needs to be tracked must, itself, start up its
-// tracker with the start() method and then call the update() method
-// at regular intervals. What the tracker does is to calculate the
-// concurrent overhead of a process at a given update period. The
-// tracker starts and when is detects that it has exceeded the given
-// period, it calculates the duration of the period in wall-clock time
-// and the duration of the period in vtime (i.e. how much time the
-// concurrent processes really took up during this period). The ratio
-// of the latter over the former is the concurrent overhead of that
-// process for that period over a single CPU. This overhead is stored
-// on the tracker, "timestamped" with the wall-clock time of the end
-// of the period. When the concurrent overhead of this process needs
-// to be queried, this last "reading" provides a good approximation
-// (we assume that the concurrent overhead of a particular thread
-// stays largely constant over time). The timestamp is necessary to
-// detect when the process has stopped working and the recorded
-// reading hasn't been updated for some time.
-
-// Each concurrent GC thread is considered to be part of a "group"
-// (i.e. any available concurrent marking threads are part of the
-// "concurrent marking thread group"). A COTracker is associated with
-// a single group at construction-time. It's up to each collector to
-// decide how groups will be mapped to such an id (ids should start
-// from 0 and be consecutive; there's a hardcoded max group num
-// defined on the GCOverheadTracker class). The notion of a group has
-// been introduced to be able to identify how much overhead was
-// imposed by each group, instead of getting a single value that
-// covers all concurrent overhead.
-
-class COTracker {
-private:
- // It indicates whether this tracker is enabled or not. When the
- // tracker is disabled, then it returns 0.0 as the latest concurrent
- // overhead and several methods (reset, start, and update) are not
- // supposed to be called on it. This enabling / disabling facility
- // is really provided to make a bit more explicit in the code when a
- // particulary tracker of a processes that doesn't run all the time
- // (e.g. concurrent marking) is supposed to be used and not it's not.
- bool _enabled;
-
- // The ID of the group associated with this tracker.
- int _group;
-
- // The update period of the tracker. A new value for the concurrent
- // overhead of the associated process will be made at intervals no
- // smaller than this.
- double _update_period_sec;
-
- // The start times (both wall-block time and vtime) of the current
- // interval.
- double _period_start_time_sec;
- double _period_start_vtime_sec;
-
- // Number seq of the concurrent overhead readings within a period
- NumberSeq _conc_overhead_seq;
-
- // The latest reading of the concurrent overhead (over a single CPU)
- // imposed by the associated concurrent thread, made available at
- // the indicated wall-clock time.
- double _conc_overhead;
- double _time_stamp_sec;
-
- // The number of CPUs that the host machine has (for convenience
- // really, as we'd have to keep translating it into a double)
- static double _cpu_number;
-
- // Fields that keep a list of all trackers created. This is useful,
- // since it allows us to sum up the concurrent overhead without
- // having to write code for a specific collector to broadcast a
- // request to all its concurrent processes.
- COTracker* _next;
- static COTracker* _head;
-
- // It indicates that a new period is starting by updating the
- // _period_start_time_sec and _period_start_vtime_sec fields.
- void resetPeriod(double now_sec, double vnow_sec);
- // It updates the latest concurrent overhead reading, taken at a
- // given wall-clock time.
- void setConcOverhead(double time_stamp_sec, double conc_overhead);
-
- // It determines whether the time stamp of the latest concurrent
- // overhead reading is out of date or not.
- bool outOfDate(double now_sec) {
- // The latest reading is considered out of date, if it was taken
- // 1.2x the update period.
- return (now_sec - _time_stamp_sec) > 1.2 * _update_period_sec;
- }
-
-public:
- // The constructor which associates the tracker with a group ID.
- COTracker(int group);
-
- // Methods to enable / disable the tracker and query whether it is enabled.
- void enable() { _enabled = true; }
- void disable() { _enabled = false; }
- bool enabled() { return _enabled; }
-
- // It resets the tracker and sets concurrent overhead reading to be
- // the given parameter and the associated time stamp to be now.
- void reset(double starting_conc_overhead = 0.0);
- // The tracker starts tracking. IT should only be called from the
- // concurrent thread that is tracked by this tracker.
- void start();
- // It updates the tracker and, if the current period is longer than
- // the update period, the concurrent overhead reading will be
- // updated. force_end being true indicates that it's the last call
- // to update() by this process before the tracker is disabled (the
- // tracker can be re-enabled later if necessary). It should only be
- // called from the concurrent thread that is tracked by this tracker
- // and while the thread has joined the STS.
- void update(bool force_end = false);
- // It adjusts the contents of the tracker to take into account a STW
- // pause.
- void updateForSTW(double start_sec, double end_sec);
-
- // It returns the last concurrent overhead reading over a single
- // CPU. If the reading is out of date, or the tracker is disabled,
- // it returns 0.0.
- double concCPUOverhead(double now_sec) {
- if (!_enabled || outOfDate(now_sec))
- return 0.0;
- else
- return _conc_overhead;
- }
-
- // It returns the last concurrent overhead reading over all CPUs
- // that the host machine has. If the reading is out of date, or the
- // tracker is disabled, it returns 0.0.
- double concOverhead(double now_sec) {
- return concCPUOverhead(now_sec) / _cpu_number;
- }
-
- double predConcOverhead();
-
- void resetPred();
-
- // statics
-
- // It notifies all trackers about a STW pause.
- static void updateAllForSTW(double start_sec, double end_sec);
-
- // It returns the sum of the concurrent overhead readings of all
- // available (and enabled) trackers for the given time stamp. The
- // overhead is over all the CPUs of the host machine.
-
- static double totalConcOverhead(double now_sec);
- // Like the previous method, but it also sums up the overheads per
- // group number. The length of the co_per_group array must be at
- // least as large group_num
- static double totalConcOverhead(double now_sec,
- size_t group_num,
- double* co_per_group);
-
- static double totalPredConcOverhead();
-};