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