5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_GC_G1_G1YOUNGREMSETSAMPLINGTHREAD_HPP
26 #define SHARE_GC_G1_G1YOUNGREMSETSAMPLINGTHREAD_HPP
27
28 #include "gc/shared/concurrentGCThread.hpp"
29
30 // The G1YoungRemSetSamplingThread is used to re-assess the validity of
31 // the prediction for the remembered set lengths of the young generation.
32 //
33 // At the end of the GC G1 determines the length of the young gen based on
34 // how much time the next GC can take, and when the next GC may occur
35 // according to the MMU.
36 //
37 // The assumption is that a significant part of the GC is spent on scanning
38 // the remembered sets (and many other components), so this thread constantly
39 // reevaluates the prediction for the remembered set scanning costs, and potentially
40 // G1Policy resizes the young gen. This may do a premature GC or even
41 // increase the young gen size to keep pause time length goal.
42 class G1YoungRemSetSamplingThread: public ConcurrentGCThread {
43 private:
44 Monitor _monitor;
45
46 double _last_periodic_gc_attempt_s;
47
48 double _vtime_accum; // Accumulated virtual time.
49
50 void sample_young_list_rs_length();
51
52 void run_service();
53 void check_for_periodic_gc();
54
55 void stop_service();
56
57 void sleep_before_next_cycle();
58
59 bool should_start_periodic_gc();
60
61 public:
62 G1YoungRemSetSamplingThread();
63 double vtime_accum() { return _vtime_accum; }
64 };
65
66 #endif // SHARE_GC_G1_G1YOUNGREMSETSAMPLINGTHREAD_HPP
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5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_GC_G1_G1SERVICETHREAD_HPP
26 #define SHARE_GC_G1_G1SERVICETHREAD_HPP
27
28 #include "gc/shared/concurrentGCThread.hpp"
29
30 // The G1ServiceThread is used to periodically do a number of different tasks:
31 // - re-assess the validity of the prediction for the
32 // remembered set lengths of the young generation.
33 // - check if a periodic GC should be scheduled.
34 class G1ServiceThread: public ConcurrentGCThread {
35 private:
36 Monitor _monitor;
37
38 double _last_periodic_gc_attempt_s;
39
40 double _vtime_accum; // Accumulated virtual time.
41
42 // Sample the current length of remembered sets for young.
43 //
44 // At the end of the GC G1 determines the length of the young gen based on
45 // how much time the next GC can take, and when the next GC may occur
46 // according to the MMU.
47 //
48 // The assumption is that a significant part of the GC is spent on scanning
49 // the remembered sets (and many other components), so this thread constantly
50 // reevaluates the prediction for the remembered set scanning costs, and potentially
51 // G1Policy resizes the young gen. This may do a premature GC or even
52 // increase the young gen size to keep pause time length goal.
53 void sample_young_list_rs_length();
54
55 void run_service();
56 void check_for_periodic_gc();
57
58 void stop_service();
59
60 void sleep_before_next_cycle();
61
62 bool should_start_periodic_gc();
63
64 public:
65 G1ServiceThread();
66 double vtime_accum() { return _vtime_accum; }
67 };
68
69 #endif // SHARE_GC_G1_G1SERVICETHREAD_HPP
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