1 /*
  2  * Copyright (c) 2017, 2021, Red Hat, Inc. All rights reserved.
  3  * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
  4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  5  *
  6  * This code is free software; you can redistribute it and/or modify it
  7  * under the terms of the GNU General Public License version 2 only, as
  8  * published by the Free Software Foundation.
  9  *
 10  * This code is distributed in the hope that it will be useful, but WITHOUT
 11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 13  * version 2 for more details (a copy is included in the LICENSE file that
 14  * accompanied this code).
 15  *
 16  * You should have received a copy of the GNU General Public License version
 17  * 2 along with this work; if not, write to the Free Software Foundation,
 18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 19  *
 20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 21  * or visit www.oracle.com if you need additional information or have any
 22  * questions.
 23  *
 24  */
 25 
 26 #include "precompiled.hpp"
 27 
 28 #include "gc/shared/workerDataArray.inline.hpp"
 29 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
 30 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
 31 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
 32 #include "gc/shenandoah/shenandoahUtils.hpp"
 33 #include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
 34 #include "runtime/orderAccess.hpp"
 35 #include "utilities/ostream.hpp"
 36 
 37 #define SHENANDOAH_PHASE_NAME_FORMAT "%-30s"
 38 #define SHENANDOAH_S_TIME_FORMAT "%8.3lf"
 39 #define SHENANDOAH_US_TIME_FORMAT "%8.0lf"
 40 #define SHENANDOAH_US_WORKER_TIME_FORMAT "%3.0lf"
 41 #define SHENANDOAH_US_WORKER_NOTIME_FORMAT "%3s"
 42 #define SHENANDOAH_PARALLELISM_FORMAT "%4.2lf"
 43 
 44 #define SHENANDOAH_PHASE_DECLARE_NAME(type, title) \
 45   title,
 46 
 47 const char* ShenandoahPhaseTimings::_phase_names[] = {
 48   SHENANDOAH_PHASE_DO(SHENANDOAH_PHASE_DECLARE_NAME)
 49 };
 50 
 51 #undef SHENANDOAH_PHASE_DECLARE_NAME
 52 
 53 ShenandoahPhaseTimings::ShenandoahPhaseTimings(uint max_workers) :
 54   _max_workers(max_workers) {
 55   assert(_max_workers > 0, "Must have some GC threads");
 56 
 57   // Initialize everything to sane defaults
 58   for (uint i = 0; i < _num_phases; i++) {
 59 #define SHENANDOAH_WORKER_DATA_NULL(type, title) \
 60     _worker_data[i] = nullptr;
 61     SHENANDOAH_PAR_PHASE_DO(,, SHENANDOAH_WORKER_DATA_NULL)
 62 #undef SHENANDOAH_WORKER_DATA_NULL
 63     _cycle_data[i] = uninitialized();
 64   }
 65 
 66   // Then punch in the worker-related data.
 67   // Every worker phase get a bunch of internal objects, except
 68   // the very first slot, which is "<total>" and is not populated.
 69   for (uint i = 0; i < _num_phases; i++) {
 70     if (is_worker_phase(Phase(i))) {
 71       int c = 0;
 72 #define SHENANDOAH_WORKER_DATA_INIT(type, title) \
 73       if (c++ != 0) _worker_data[i + c] = new ShenandoahWorkerData(nullptr, title, _max_workers);
 74       SHENANDOAH_PAR_PHASE_DO(,, SHENANDOAH_WORKER_DATA_INIT)
 75 #undef SHENANDOAH_WORKER_DATA_INIT
 76     }
 77   }
 78 
 79   _policy = ShenandoahHeap::heap()->shenandoah_policy();
 80   assert(_policy != nullptr, "Can not be null");
 81 }
 82 
 83 ShenandoahPhaseTimings::Phase ShenandoahPhaseTimings::worker_par_phase(Phase phase, ParPhase par_phase) {
 84   assert(is_worker_phase(phase), "Phase should accept worker phase times: %s", phase_name(phase));
 85   Phase p = Phase(phase + 1 + par_phase);
 86   assert(p >= 0 && p < _num_phases, "Out of bound for: %s", phase_name(phase));
 87   return p;
 88 }
 89 
 90 ShenandoahWorkerData* ShenandoahPhaseTimings::worker_data(Phase phase, ParPhase par_phase) {
 91   Phase p = worker_par_phase(phase, par_phase);
 92   ShenandoahWorkerData* wd = _worker_data[p];
 93   assert(wd != nullptr, "Counter initialized: %s", phase_name(p));
 94   return wd;
 95 }
 96 
 97 bool ShenandoahPhaseTimings::is_worker_phase(Phase phase) {
 98   assert(phase >= 0 && phase < _num_phases, "Out of bounds");
 99   switch (phase) {
100     case init_evac:
101     case init_scan_rset:
102     case finish_mark:
103     case purge_weak_par:
104     case full_gc_mark:
105     case full_gc_update_roots:
106     case full_gc_adjust_roots:
107     case degen_gc_stw_mark:
108     case degen_gc_mark:
109     case degen_gc_update_roots:
110     case full_gc_weakrefs:
111     case full_gc_purge_class_unload:
112     case full_gc_purge_weak_par:
113     case degen_gc_weakrefs:
114     case degen_gc_purge_class_unload:
115     case degen_gc_purge_weak_par:
116     case heap_iteration_roots:
117     case conc_mark:
118     case conc_mark_roots:
119     case conc_thread_roots:
120     case conc_weak_roots_work:
121     case conc_weak_refs:
122     case conc_strong_roots:
123       return true;
124     default:
125       return false;
126   }
127 }
128 
129 bool ShenandoahPhaseTimings::is_root_work_phase(Phase phase) {
130   switch (phase) {
131     case finish_mark:
132     case init_evac:
133     case degen_gc_update_roots:
134     case full_gc_mark:
135     case full_gc_update_roots:
136     case full_gc_adjust_roots:
137       return true;
138     default:
139       return false;
140   }
141 }
142 
143 void ShenandoahPhaseTimings::set_cycle_data(Phase phase, double time) {
144 #ifdef ASSERT
145   double d = _cycle_data[phase];
146   assert(d == uninitialized(), "Should not be set yet: %s, current value: %lf", phase_name(phase), d);
147 #endif
148   _cycle_data[phase] = time;
149 }
150 
151 void ShenandoahPhaseTimings::record_phase_time(Phase phase, double time) {
152   if (!_policy->is_at_shutdown()) {
153     set_cycle_data(phase, time);
154   }
155 }
156 
157 void ShenandoahPhaseTimings::record_workers_start(Phase phase) {
158   assert(is_worker_phase(phase), "Phase should accept worker phase times: %s", phase_name(phase));
159 
160   // Special case: these phases can enter multiple times, need to reset
161   // their worker data every time.
162   if (phase == heap_iteration_roots) {
163     for (uint i = 1; i < _num_par_phases; i++) {
164       worker_data(phase, ParPhase(i))->reset();
165     }
166   }
167 
168 #ifdef ASSERT
169   for (uint i = 1; i < _num_par_phases; i++) {
170     ShenandoahWorkerData* wd = worker_data(phase, ParPhase(i));
171     for (uint c = 0; c < _max_workers; c++) {
172       assert(wd->get(c) == ShenandoahWorkerData::uninitialized(),
173              "Should not be set: %s", phase_name(worker_par_phase(phase, ParPhase(i))));
174     }
175   }
176 #endif
177 }
178 
179 void ShenandoahPhaseTimings::record_workers_end(Phase phase) {
180   assert(is_worker_phase(phase), "Phase should accept worker phase times: %s", phase_name(phase));
181 }
182 
183 void ShenandoahPhaseTimings::flush_par_workers_to_cycle() {
184   for (uint pi = 0; pi < _num_phases; pi++) {
185     Phase phase = Phase(pi);
186     if (is_worker_phase(phase)) {
187       double s = uninitialized();
188       for (uint i = 1; i < _num_par_phases; i++) {
189         ShenandoahWorkerData* wd = worker_data(phase, ParPhase(i));
190         double ws = uninitialized();
191         for (uint c = 0; c < _max_workers; c++) {
192           double v = wd->get(c);
193           if (v != ShenandoahWorkerData::uninitialized()) {
194             if (ws == uninitialized()) {
195               ws = v;
196             } else {
197               ws += v;
198             }
199           }
200         }
201         if (ws != uninitialized()) {
202           // add to each line in phase
203           set_cycle_data(Phase(phase + i + 1), ws);
204           if (s == uninitialized()) {
205             s = ws;
206           } else {
207             s += ws;
208           }
209         }
210       }
211       if (s != uninitialized()) {
212         // add to total for phase
213         set_cycle_data(Phase(phase + 1), s);
214       }
215     }
216   }
217 }
218 
219 void ShenandoahPhaseTimings::flush_cycle_to_global() {
220   for (uint i = 0; i < _num_phases; i++) {
221     if (_cycle_data[i] != uninitialized()) {
222       _global_data[i].add(_cycle_data[i]);
223       _cycle_data[i] = uninitialized();
224     }
225     if (_worker_data[i] != nullptr) {
226       _worker_data[i]->reset();
227     }
228   }
229   OrderAccess::fence();
230 }
231 
232 void ShenandoahPhaseTimings::print_cycle_on(outputStream* out) const {
233   out->cr();
234   out->print_cr("All times are wall-clock times, except per-root-class counters, that are sum over");
235   out->print_cr("all workers. Dividing the <total> over the root stage time estimates parallelism.");
236   out->cr();
237   for (uint i = 0; i < _num_phases; i++) {
238     double v = _cycle_data[i] * 1000000.0;
239     if (v > 0) {
240       out->print(SHENANDOAH_PHASE_NAME_FORMAT " " SHENANDOAH_US_TIME_FORMAT " us", _phase_names[i], v);
241 
242       if (is_worker_phase(Phase(i))) {
243         double total = _cycle_data[i + 1] * 1000000.0;
244         if (total > 0) {
245           out->print(", parallelism: " SHENANDOAH_PARALLELISM_FORMAT "x", total / v);
246         }
247       }
248 
249       if (_worker_data[i] != nullptr) {
250         out->print(", workers (us): ");
251         for (uint c = 0; c < _max_workers; c++) {
252           double tv = _worker_data[i]->get(c);
253           if (tv != ShenandoahWorkerData::uninitialized()) {
254             out->print(SHENANDOAH_US_WORKER_TIME_FORMAT ", ", tv * 1000000.0);
255           } else {
256             out->print(SHENANDOAH_US_WORKER_NOTIME_FORMAT ", ", "---");
257           }
258         }
259       }
260       out->cr();
261     }
262   }
263 }
264 
265 void ShenandoahPhaseTimings::print_global_on(outputStream* out) const {
266   out->cr();
267   out->print_cr("GC STATISTICS:");
268   out->print_cr("  \"(G)\" (gross) pauses include VM time: time to notify and block threads, do the pre-");
269   out->print_cr("        and post-safepoint housekeeping. Use -Xlog:safepoint+stats to dissect.");
270   out->print_cr("  \"(N)\" (net) pauses are the times spent in the actual GC code.");
271   out->print_cr("  \"a\" is average time for each phase, look at levels to see if average makes sense.");
272   out->print_cr("  \"lvls\" are quantiles: 0%% (minimum), 25%%, 50%% (median), 75%%, 100%% (maximum).");
273   out->cr();
274   out->print_cr("  All times are wall-clock times, except per-root-class counters, that are sum over");
275   out->print_cr("  all workers. Dividing the <total> over the root stage time estimates parallelism.");
276   out->cr();
277 
278   out->print_cr("  Pacing delays are measured from entering the pacing code till exiting it. Therefore,");
279   out->print_cr("  observed pacing delays may be higher than the threshold when paced thread spent more");
280   out->print_cr("  time in the pacing code. It usually happens when thread is de-scheduled while paced,");
281   out->print_cr("  OS takes longer to unblock the thread, or JVM experiences an STW pause.");
282   out->cr();
283   out->print_cr("  Higher delay would prevent application outpacing the GC, but it will hide the GC latencies");
284   out->print_cr("  from the STW pause times. Pacing affects the individual threads, and so it would also be");
285   out->print_cr("  invisible to the usual profiling tools, but would add up to end-to-end application latency.");
286   out->print_cr("  Raise max pacing delay with care.");
287   out->cr();
288 
289   for (uint i = 0; i < _num_phases; i++) {
290     if (_global_data[i].maximum() != 0) {
291       out->print_cr(SHENANDOAH_PHASE_NAME_FORMAT " = " SHENANDOAH_S_TIME_FORMAT " s "
292                     "(a = " SHENANDOAH_US_TIME_FORMAT " us) "
293                     "(n = " INT32_FORMAT_W(5) ") (lvls, us = "
294                     SHENANDOAH_US_TIME_FORMAT ", "
295                     SHENANDOAH_US_TIME_FORMAT ", "
296                     SHENANDOAH_US_TIME_FORMAT ", "
297                     SHENANDOAH_US_TIME_FORMAT ", "
298                     SHENANDOAH_US_TIME_FORMAT ")",
299                     _phase_names[i],
300                     _global_data[i].sum(),
301                     _global_data[i].avg() * 1000000.0,
302                     _global_data[i].num(),
303                     _global_data[i].percentile(0) * 1000000.0,
304                     _global_data[i].percentile(25) * 1000000.0,
305                     _global_data[i].percentile(50) * 1000000.0,
306                     _global_data[i].percentile(75) * 1000000.0,
307                     _global_data[i].maximum() * 1000000.0
308       );
309     }
310   }
311 }
312 
313 ShenandoahWorkerTimingsTracker::ShenandoahWorkerTimingsTracker(ShenandoahPhaseTimings::Phase phase,
314         ShenandoahPhaseTimings::ParPhase par_phase, uint worker_id, bool cumulative) :
315         _timings(ShenandoahHeap::heap()->phase_timings()),
316         _phase(phase), _par_phase(par_phase), _worker_id(worker_id) {
317 
318   assert(_timings->worker_data(_phase, _par_phase)->get(_worker_id) == ShenandoahWorkerData::uninitialized() || cumulative,
319          "Should not be set yet: %s", ShenandoahPhaseTimings::phase_name(_timings->worker_par_phase(_phase, _par_phase)));
320   _start_time = os::elapsedTime();
321 }
322 
323 ShenandoahWorkerTimingsTracker::~ShenandoahWorkerTimingsTracker() {
324   _timings->worker_data(_phase, _par_phase)->set_or_add(_worker_id, os::elapsedTime() - _start_time);
325 
326   if (ShenandoahPhaseTimings::is_root_work_phase(_phase)) {
327     ShenandoahPhaseTimings::Phase root_phase = _phase;
328     ShenandoahPhaseTimings::Phase cur_phase = _timings->worker_par_phase(root_phase, _par_phase);
329     _event.commit(GCId::current(), _worker_id, ShenandoahPhaseTimings::phase_name(cur_phase));
330   }
331 }