1 /*
2 * Copyright (c) 2017, 2019, 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 "jfr/periodic/jfrThreadCPULoadEvent.hpp"
27 #include "jfr/recorder/access/jfrThreadData.hpp"
28 #include "jfr/utilities/jfrTraceTime.hpp"
29 #include "utilities/globalDefinitions.hpp"
30 #include "runtime/os.hpp"
31 #include "runtime/thread.inline.hpp"
32 #include "tracefiles/traceEventClasses.hpp"
33
34 jlong JfrThreadCPULoadEvent::get_wallclock_time() {
35 return os::javaTimeNanos();
36 }
37
38 int JfrThreadCPULoadEvent::_last_active_processor_count = 0;
39
40 int JfrThreadCPULoadEvent::get_processor_count() {
41 int cur_processor_count = os::active_processor_count();
42 int last_processor_count = _last_active_processor_count;
43 _last_active_processor_count = cur_processor_count;
44
45 // If the number of processors decreases, we don't know at what point during
46 // the sample interval this happened, so use the largest number to try
47 // to avoid percentages above 100%
48 return MAX2(cur_processor_count, last_processor_count);
49 }
50
51 // Returns false if the thread has not been scheduled since the last call to updateEvent
52 // (i.e. the delta for both system and user time is 0 milliseconds)
53 bool JfrThreadCPULoadEvent::update_event(EventThreadCPULoad& event, JavaThread* thread, jlong cur_wallclock_time, int processor_count) {
54 JfrThreadData* thread_data = thread->trace_data();
55
56 jlong cur_cpu_time = os::thread_cpu_time(thread, true);
57 jlong prev_cpu_time = thread_data->get_cpu_time();
58
59 jlong prev_wallclock_time = thread_data->get_wallclock_time();
60 thread_data->set_wallclock_time(cur_wallclock_time);
61
62 // Threshold of 1 ms
63 if (cur_cpu_time - prev_cpu_time < 1 * NANOSECS_PER_MILLISEC) {
64 return false;
65 }
66
67 jlong cur_user_time = os::thread_cpu_time(thread, false);
68 jlong prev_user_time = thread_data->get_user_time();
69
70 jlong cur_system_time = cur_cpu_time - cur_user_time;
71 jlong prev_system_time = prev_cpu_time - prev_user_time;
72
73 // The user and total cpu usage clocks can have different resolutions, which can
74 // make us see decreasing system time. Ensure time doesn't go backwards.
75 if (prev_system_time > cur_system_time) {
76 cur_system_time = prev_system_time;
77 }
78
79 jlong user_time = cur_user_time - prev_user_time;
80 jlong system_time = cur_system_time - prev_system_time;
81 jlong wallclock_time = cur_wallclock_time - prev_wallclock_time;
82 jlong total_available_time = wallclock_time * processor_count;
83
84 // Avoid reporting percentages above the theoretical max
85 if (user_time + system_time > wallclock_time) {
86 jlong excess = user_time + system_time - wallclock_time;
87 if (user_time > excess) {
88 user_time -= excess;
89 cur_user_time -= excess;
90 } else {
91 excess -= user_time;
92 user_time = 0;
93 cur_user_time = 0;
94 system_time -= excess;
95 cur_system_time -= excess;
96 }
97 }
98 event.set_user(total_available_time > 0 ? (double)user_time / total_available_time : 0);
99 event.set_system(total_available_time > 0 ? (double)system_time / total_available_time : 0);
100 thread_data->set_user_time(cur_user_time);
101 thread_data->set_cpu_time(cur_cpu_time);
102 return true;
103 }
104
105 void JfrThreadCPULoadEvent::send_events() {
106 Thread* periodic_thread = Thread::current();
107 JfrThreadData* const periodic_trace_data = periodic_thread->trace_data();
108 traceid periodic_thread_id = periodic_trace_data->thread_id();
109 const int processor_count = JfrThreadCPULoadEvent::get_processor_count();
110 JfrTraceTime event_time = JfrTraceTime::now();
111 jlong cur_wallclock_time = JfrThreadCPULoadEvent::get_wallclock_time();
112
113 JavaThread *jt = Threads::first();
114 size_t thread_count = 0;
115 while (jt) {
116 thread_count++;
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 jt = jt->next();
129 }
130 log_trace(jfr)("Measured CPU usage for %d threads in %.3f milliseconds", thread_count,
131 (double)(JfrTraceTime::now() - event_time) / (JfrTraceTime::frequency() / 1000));
132 // Restore this thread's thread id
133 periodic_trace_data->set_thread_id(periodic_thread_id);
134 }
135
136 void JfrThreadCPULoadEvent::send_event_for_thread(JavaThread* jt) {
137 EventThreadCPULoad event;
138 if (event.should_commit()) {
139 if (update_event(event, jt, get_wallclock_time(), get_processor_count())) {
140 event.commit();
141 }
142 }
143 }