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/jfrEvents.hpp"

    28 #include "jfr/periodic/jfrThreadCPULoadEvent.hpp"

    29 #include "jfr/support/jfrThreadId.hpp"

    30 #include "jfr/support/jfrThreadLocal.hpp"

    31 #include "jfr/utilities/jfrTime.hpp"

    32 #include "utilities/globalDefinitions.hpp"

    33 #include "runtime/os.hpp"

    34 #include "runtime/thread.inline.hpp"

    35 #include "runtime/threadSMR.inline.hpp"

    36 

    37 jlong JfrThreadCPULoadEvent::get_wallclock_time() {

    38   return os::javaTimeNanos();

    39 }

    40 

    41 int JfrThreadCPULoadEvent::_last_active_processor_count = 0;

    42 

    43 int JfrThreadCPULoadEvent::get_processor_count() {

    44   int cur_processor_count = os::active_processor_count();

    45   int last_processor_count = _last_active_processor_count;

    46   _last_active_processor_count = cur_processor_count;

    47 

    48   // If the number of processors decreases, we don't know at what point during

    49   // the sample interval this happened, so use the largest number to try

    50   // to avoid percentages above 100%

    51   return MAX2(cur_processor_count, last_processor_count);

    52 }

    53 

    54 // Returns false if the thread has not been scheduled since the last call to updateEvent

    55 // (i.e. the delta for both system and user time is 0 milliseconds)

    56 bool JfrThreadCPULoadEvent::update_event(EventThreadCPULoad& event, JavaThread* thread, jlong cur_wallclock_time, int processor_count) {

    57   JfrThreadLocal* const tl = thread->jfr_thread_local();

    58 

    59   jlong cur_cpu_time = os::thread_cpu_time(thread, true);

    60   jlong prev_cpu_time = tl->get_cpu_time();

    61 

    62   jlong prev_wallclock_time = tl->get_wallclock_time();

    63   tl->set_wallclock_time(cur_wallclock_time);

    64 

    65   // Threshold of 1 ms

    66   if (cur_cpu_time - prev_cpu_time < 1 * NANOSECS_PER_MILLISEC) {

    67     return false;

    68   }

    69 

    70   jlong cur_user_time = os::thread_cpu_time(thread, false);

    71   jlong prev_user_time = tl->get_user_time();

    72 

    73   jlong cur_system_time = cur_cpu_time - cur_user_time;

    74   jlong prev_system_time = prev_cpu_time - prev_user_time;

    75 

    76   // The user and total cpu usage clocks can have different resolutions, which can

    77   // make us see decreasing system time. Ensure time doesn't go backwards.

    78   if (prev_system_time > cur_system_time) {

    79     cur_cpu_time += prev_system_time - cur_system_time;

    80     cur_system_time = prev_system_time;

    81   }

    82 

    83   jlong user_time = cur_user_time - prev_user_time;

    84   jlong system_time = cur_system_time - prev_system_time;

    85   jlong wallclock_time = cur_wallclock_time - prev_wallclock_time;

    86   jlong total_available_time = wallclock_time * processor_count;

    87 

    88   // Avoid reporting percentages above the theoretical max

    89   if (user_time + system_time > wallclock_time) {

    90     jlong excess = user_time + system_time - wallclock_time;

    91     if (user_time > excess) {

    92       user_time -= excess;

    93       cur_user_time -= excess;

    94       cur_cpu_time -= excess;

    95     } else {

    96       cur_cpu_time -= excess;

    97       excess -= user_time;

    98       user_time = 0;

    99       cur_user_time = 0;

   100       system_time -= excess;

   101     }

   102   }

   103   event.set_user(total_available_time > 0 ? (double)user_time / total_available_time : 0);

   104   event.set_system(total_available_time > 0 ? (double)system_time / total_available_time : 0);

   105   tl->set_user_time(cur_user_time);

   106   tl->set_cpu_time(cur_cpu_time);

   107   return true;

   108 }

   109 

   110 void JfrThreadCPULoadEvent::send_events() {

   111   Thread* periodic_thread = Thread::current();

   112   JfrThreadLocal* const periodic_thread_tl = periodic_thread->jfr_thread_local();

   113   traceid periodic_thread_id = periodic_thread_tl->thread_id();

   114   const int processor_count = JfrThreadCPULoadEvent::get_processor_count();

   115   JfrTicks event_time = JfrTicks::now();

   116   jlong cur_wallclock_time = JfrThreadCPULoadEvent::get_wallclock_time();

   117 

   118   JavaThreadIteratorWithHandle jtiwh;

   119   while (JavaThread* jt = jtiwh.next()) {

   120     EventThreadCPULoad event(UNTIMED);

   121     if (JfrThreadCPULoadEvent::update_event(event, jt, cur_wallclock_time, processor_count)) {

   122       event.set_starttime(event_time);

   123       if (jt != periodic_thread) {

   124         // Commit reads the thread id from this thread's trace data, so put it there temporarily

   125         periodic_thread_tl->set_thread_id(JFR_THREAD_ID(jt));

   126       } else {

   127         periodic_thread_tl->set_thread_id(periodic_thread_id);

   128       }

   129       event.commit();

   130     }

   131   }

   132   log_trace(jfr)("Measured CPU usage for %d threads in %.3f milliseconds", jtiwh.length(),

   133     (double)(JfrTicks::now() - event_time).milliseconds());

   134   // Restore this thread's thread id

   135   periodic_thread_tl->set_thread_id(periodic_thread_id);

   136 }

   137 

   138 void JfrThreadCPULoadEvent::send_event_for_thread(JavaThread* jt) {

   139   EventThreadCPULoad event;

   140   if (event.should_commit()) {

   141     if (update_event(event, jt, get_wallclock_time(), get_processor_count())) {

   142       event.commit();

   143     }

   144   }

   145 }