1 /*
2 * Copyright (c) 2017, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
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 #include "precompiled.hpp"
26 #include "logging/log.hpp"
27 #include "jfr/periodic/jfrThreadCPULoadEvent.hpp"
28 #include "jfr/recorder/access/jfrThreadData.hpp"
29 #include "jfr/utilities/jfrTraceTime.hpp"
30 #include "utilities/globalDefinitions.hpp"
31 #include "runtime/os.hpp"
32 #include "runtime/thread.inline.hpp"
33 #include "runtime/threadSMR.inline.hpp"
34 #include "tracefiles/traceEventClasses.hpp"
35
36 jlong JfrThreadCPULoadEvent::get_wallclock_time() {
37 return os::javaTimeNanos();
38 }
39
40 int JfrThreadCPULoadEvent::_last_active_processor_count = 0;
41
42 int JfrThreadCPULoadEvent::get_processor_count() {
43 int cur_processor_count = os::active_processor_count();
44 int last_processor_count = _last_active_processor_count;
45 _last_active_processor_count = cur_processor_count;
46
47 // If the number of processors decreases, we don't know at what point during
48 // the sample interval this happened, so use the largest number to try
49 // to avoid percentages above 100%
50 return MAX2(cur_processor_count, last_processor_count);
51 }
52
53 // Returns false if the thread has not been scheduled since the last call to updateEvent
54 // (i.e. the delta for both system and user time is 0 milliseconds)
55 bool JfrThreadCPULoadEvent::update_event(EventThreadCPULoad& event, JavaThread* thread, jlong cur_wallclock_time, int processor_count) {
56 JfrThreadData* thread_data = thread->trace_data();
57
58 jlong cur_cpu_time = os::thread_cpu_time(thread, true);
59 jlong prev_cpu_time = thread_data->get_cpu_time();
60
61 jlong prev_wallclock_time = thread_data->get_wallclock_time();
62 thread_data->set_wallclock_time(cur_wallclock_time);
63
64 // Threshold of 1 ms
65 if (cur_cpu_time - prev_cpu_time < 1 * NANOSECS_PER_MILLISEC) {
66 return false;
67 }
68
69 jlong cur_user_time = os::thread_cpu_time(thread, false);
70 jlong prev_user_time = thread_data->get_user_time();
71
72 jlong cur_system_time = cur_cpu_time - cur_user_time;
73 jlong prev_system_time = prev_cpu_time - prev_user_time;
74
75 // The user and total cpu usage clocks can have different resolutions, which can
76 // make us see decreasing system time. Ensure time doesn't go backwards.
77 if (prev_system_time > cur_system_time) {
78 cur_system_time = prev_system_time;
79 }
80
81 jlong user_time = cur_user_time - prev_user_time;
82 jlong system_time = cur_system_time - prev_system_time;
83 jlong wallclock_time = cur_wallclock_time - prev_wallclock_time;
84 jlong total_available_time = wallclock_time * processor_count;
85
86 // Avoid reporting percentages above the theoretical max
87 if (user_time + system_time > wallclock_time) {
88 jlong excess = user_time + system_time - wallclock_time;
89 if (user_time > excess) {
90 user_time -= excess;
91 cur_user_time -= excess;
92 } else {
93 excess -= user_time;
94 user_time = 0;
95 cur_user_time = 0;
96 system_time -= excess;
97 cur_system_time -= excess;
98 }
99 }
100 event.set_user(total_available_time > 0 ? (double)user_time / total_available_time : 0);
101 event.set_system(total_available_time > 0 ? (double)system_time / total_available_time : 0);
102 thread_data->set_user_time(cur_user_time);
103 thread_data->set_cpu_time(cur_cpu_time);
104 return true;
105 }
106
107 void JfrThreadCPULoadEvent::send_events() {
108 Thread* periodic_thread = Thread::current();
109 JfrThreadData* const periodic_trace_data = periodic_thread->trace_data();
110 traceid periodic_thread_id = periodic_trace_data->thread_id();
111 const int processor_count = JfrThreadCPULoadEvent::get_processor_count();
112 JfrTraceTime event_time = JfrTraceTime::now();
113 jlong cur_wallclock_time = JfrThreadCPULoadEvent::get_wallclock_time();
114
115 JavaThreadIteratorWithHandle jtiwh;
116 while (JavaThread* jt = jtiwh.next()) {
117 EventThreadCPULoad event(UNTIMED);
118 if (JfrThreadCPULoadEvent::update_event(event, jt, cur_wallclock_time, processor_count)) {
119 event.set_starttime(event_time);
120 if (jt != periodic_thread) {
121 // Commit reads the thread id from this thread's trace data, so put it there temporarily
122 periodic_trace_data->set_thread_id(THREAD_TRACE_ID(jt));
123 } else {
124 periodic_trace_data->set_thread_id(periodic_thread_id);
125 }
126 event.commit();
127 }
128 }
129 log_trace(jfr)("Measured CPU usage for %d threads in %.3f milliseconds", jtiwh.length(),
130 (double)(JfrTraceTime::now() - event_time) / (JfrTraceTime::frequency() / 1000));
131 // Restore this thread's thread id
132 periodic_trace_data->set_thread_id(periodic_thread_id);
133 }
134
135 void JfrThreadCPULoadEvent::send_event_for_thread(JavaThread* jt) {
136 EventThreadCPULoad event;
137 if (event.should_commit()) {
138 if (update_event(event, jt, get_wallclock_time(), get_processor_count())) {
139 event.commit();
140 }
141 }
142 }