summaryrefslogtreecommitdiffstats
path: root/xpcom/threads/CPUUsageWatcher.cpp
blob: 922ca81e8d6cf11fe3eecd20d21cf7dea980cb3a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "mozilla/CPUUsageWatcher.h"

#include "prsystem.h"

#ifdef XP_MACOSX
#  include <sys/resource.h>
#  include <mach/clock.h>
#  include <mach/mach_host.h>
#endif

#ifdef CPU_USAGE_WATCHER_ACTIVE
#  include "mozilla/BackgroundHangMonitor.h"
#endif

namespace mozilla {

#ifdef CPU_USAGE_WATCHER_ACTIVE

// Even if the machine only has one processor, tolerate up to 50%
// external CPU usage.
static const float kTolerableExternalCPUUsageFloor = 0.5f;

struct CPUStats {
  // The average CPU usage time, which can be summed across all cores in the
  // system, or averaged between them. Whichever it is, it needs to be in the
  // same units as updateTime.
  uint64_t usageTime;
  // A monotonically increasing value in the same units as usageTime, which can
  // be used to determine the percentage of active vs idle time
  uint64_t updateTime;
};

#  ifdef XP_MACOSX

static const uint64_t kMicrosecondsPerSecond = 1000000LL;
static const uint64_t kNanosecondsPerMicrosecond = 1000LL;

static uint64_t GetMicroseconds(timeval time) {
  return ((uint64_t)time.tv_sec) * kMicrosecondsPerSecond +
         (uint64_t)time.tv_usec;
}

static uint64_t GetMicroseconds(mach_timespec_t time) {
  return ((uint64_t)time.tv_sec) * kMicrosecondsPerSecond +
         ((uint64_t)time.tv_nsec) / kNanosecondsPerMicrosecond;
}

static Result<CPUStats, CPUUsageWatcherError> GetProcessCPUStats(
    int32_t numCPUs) {
  CPUStats result = {};
  rusage usage;
  int32_t rusageResult = getrusage(RUSAGE_SELF, &usage);
  if (rusageResult == -1) {
    return Err(GetProcessTimesError);
  }
  result.usageTime =
      GetMicroseconds(usage.ru_utime) + GetMicroseconds(usage.ru_stime);

  clock_serv_t realtimeClock;
  kern_return_t errorResult =
      host_get_clock_service(mach_host_self(), REALTIME_CLOCK, &realtimeClock);
  if (errorResult != KERN_SUCCESS) {
    return Err(GetProcessTimesError);
  }
  mach_timespec_t time;
  errorResult = clock_get_time(realtimeClock, &time);
  if (errorResult != KERN_SUCCESS) {
    return Err(GetProcessTimesError);
  }
  result.updateTime = GetMicroseconds(time);

  // getrusage will give us the sum of the values across all
  // of our cores. Divide by the number of CPUs to get an average.
  result.usageTime /= numCPUs;
  return result;
}

static Result<CPUStats, CPUUsageWatcherError> GetGlobalCPUStats() {
  CPUStats result = {};
  host_cpu_load_info_data_t loadInfo;
  mach_msg_type_number_t loadInfoCount = HOST_CPU_LOAD_INFO_COUNT;
  kern_return_t statsResult =
      host_statistics(mach_host_self(), HOST_CPU_LOAD_INFO,
                      (host_info_t)&loadInfo, &loadInfoCount);
  if (statsResult != KERN_SUCCESS) {
    return Err(HostStatisticsError);
  }

  result.usageTime = loadInfo.cpu_ticks[CPU_STATE_USER] +
                     loadInfo.cpu_ticks[CPU_STATE_NICE] +
                     loadInfo.cpu_ticks[CPU_STATE_SYSTEM];
  result.updateTime = result.usageTime + loadInfo.cpu_ticks[CPU_STATE_IDLE];
  return result;
}

#  endif  // XP_MACOSX

#  ifdef XP_WIN

// A FILETIME represents the number of 100-nanosecond ticks since 1/1/1601 UTC
uint64_t FiletimeToInteger(FILETIME filetime) {
  return ((uint64_t)filetime.dwLowDateTime) | (uint64_t)filetime.dwHighDateTime
                                                  << 32;
}

Result<CPUStats, CPUUsageWatcherError> GetProcessCPUStats(int32_t numCPUs) {
  CPUStats result = {};
  FILETIME creationFiletime;
  FILETIME exitFiletime;
  FILETIME kernelFiletime;
  FILETIME userFiletime;
  bool success = GetProcessTimes(GetCurrentProcess(), &creationFiletime,
                                 &exitFiletime, &kernelFiletime, &userFiletime);
  if (!success) {
    return Err(GetProcessTimesError);
  }

  result.usageTime =
      FiletimeToInteger(kernelFiletime) + FiletimeToInteger(userFiletime);

  FILETIME nowFiletime;
  GetSystemTimeAsFileTime(&nowFiletime);
  result.updateTime = FiletimeToInteger(nowFiletime);

  result.usageTime /= numCPUs;

  return result;
}

Result<CPUStats, CPUUsageWatcherError> GetGlobalCPUStats() {
  CPUStats result = {};
  FILETIME idleFiletime;
  FILETIME kernelFiletime;
  FILETIME userFiletime;
  bool success = GetSystemTimes(&idleFiletime, &kernelFiletime, &userFiletime);

  if (!success) {
    return Err(GetSystemTimesError);
  }

  result.usageTime =
      FiletimeToInteger(kernelFiletime) + FiletimeToInteger(userFiletime);
  result.updateTime = result.usageTime + FiletimeToInteger(idleFiletime);

  return result;
}

#  endif  // XP_WIN

Result<Ok, CPUUsageWatcherError> CPUUsageWatcher::Init() {
  mNumCPUs = PR_GetNumberOfProcessors();
  if (mNumCPUs <= 0) {
    mExternalUsageThreshold = 1.0f;
    return Err(GetNumberOfProcessorsError);
  }
  mExternalUsageThreshold =
      std::max(1.0f - 1.0f / (float)mNumCPUs, kTolerableExternalCPUUsageFloor);

  CPUStats processTimes;
  MOZ_TRY_VAR(processTimes, GetProcessCPUStats(mNumCPUs));
  mProcessUpdateTime = processTimes.updateTime;
  mProcessUsageTime = processTimes.usageTime;

  CPUStats globalTimes;
  MOZ_TRY_VAR(globalTimes, GetGlobalCPUStats());
  mGlobalUpdateTime = globalTimes.updateTime;
  mGlobalUsageTime = globalTimes.usageTime;

  mInitialized = true;

  CPUUsageWatcher* self = this;
  NS_DispatchToMainThread(NS_NewRunnableFunction(
      "CPUUsageWatcher::Init",
      [=]() { BackgroundHangMonitor::RegisterAnnotator(*self); }));

  return Ok();
}

void CPUUsageWatcher::Uninit() {
  if (mInitialized) {
    BackgroundHangMonitor::UnregisterAnnotator(*this);
  }
  mInitialized = false;
}

Result<Ok, CPUUsageWatcherError> CPUUsageWatcher::CollectCPUUsage() {
  if (!mInitialized) {
    return Ok();
  }

  mExternalUsageRatio = 0.0f;

  CPUStats processTimes;
  MOZ_TRY_VAR(processTimes, GetProcessCPUStats(mNumCPUs));
  CPUStats globalTimes;
  MOZ_TRY_VAR(globalTimes, GetGlobalCPUStats());

  uint64_t processUsageDelta = processTimes.usageTime - mProcessUsageTime;
  uint64_t processUpdateDelta = processTimes.updateTime - mProcessUpdateTime;
  float processUsageNormalized =
      processUsageDelta > 0
          ? (float)processUsageDelta / (float)processUpdateDelta
          : 0.0f;

  uint64_t globalUsageDelta = globalTimes.usageTime - mGlobalUsageTime;
  uint64_t globalUpdateDelta = globalTimes.updateTime - mGlobalUpdateTime;
  float globalUsageNormalized =
      globalUsageDelta > 0 ? (float)globalUsageDelta / (float)globalUpdateDelta
                           : 0.0f;

  mProcessUsageTime = processTimes.usageTime;
  mProcessUpdateTime = processTimes.updateTime;
  mGlobalUsageTime = globalTimes.usageTime;
  mGlobalUpdateTime = globalTimes.updateTime;

  mExternalUsageRatio =
      std::max(0.0f, globalUsageNormalized - processUsageNormalized);

  return Ok();
}

void CPUUsageWatcher::AnnotateHang(BackgroundHangAnnotations& aAnnotations) {
  if (!mInitialized) {
    return;
  }

  if (mExternalUsageRatio > mExternalUsageThreshold) {
    aAnnotations.AddAnnotation(u"ExternalCPUHigh"_ns, true);
  }
}

#else  // !CPU_USAGE_WATCHER_ACTIVE

Result<Ok, CPUUsageWatcherError> CPUUsageWatcher::Init() { return Ok(); }

void CPUUsageWatcher::Uninit() {}

Result<Ok, CPUUsageWatcherError> CPUUsageWatcher::CollectCPUUsage() {
  return Ok();
}

void CPUUsageWatcher::AnnotateHang(BackgroundHangAnnotations& aAnnotations) {}

#endif  // CPU_USAGE_WATCHER_ACTIVE

}  // namespace mozilla