OLD | NEW |
---|---|
(Empty) | |
1 // Copyright (c) 2013 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include "chrome/browser/metrics/time_ticks_field_trial_win.h" | |
6 | |
7 #if defined(OS_WIN) | |
8 | |
9 #include "base/cpu.h" | |
10 #include "base/metrics/field_trial.h" | |
11 #include "base/metrics/histogram.h" | |
12 #include "base/win/windows_version.h" | |
13 | |
14 #include <windows.h> | |
15 | |
16 namespace chrome_browser_metrics { | |
17 | |
18 namespace { | |
19 | |
20 const int kNumIterations = 1000; | |
21 | |
22 } // anonymous namespace | |
23 | |
24 void CollectTimeTicksStats() { | |
25 // This bit is supposed to indicate that rdtsc is safe across cores. If so, we | |
26 // can use QPC as long as it uses rdtsc. | |
27 // TODO(simonjam): We should look for other signals that QPC might be safe and | |
28 // test them out here. | |
29 base::CPU cpu; | |
30 UMA_HISTOGRAM_BOOLEAN("WinTimeTicks.NonStopTsc", cpu.has_nonstoptsc()); | |
31 if (!cpu.has_nonstoptsc()) { | |
32 return; | |
33 } | |
34 | |
35 base::win::OSInfo* info = base::win::OSInfo::GetInstance(); | |
36 UMA_HISTOGRAM_ENUMERATION("WinTimeTicks.VersionTotal", info->version(), | |
37 base::win::VERSION_WIN_LAST); | |
38 | |
39 LARGE_INTEGER qpc_frequency; | |
40 QueryPerformanceFrequency(&qpc_frequency); | |
41 | |
42 int min_delta = 0; | |
43 LARGE_INTEGER qpc_last; | |
44 QueryPerformanceCounter(&qpc_last); | |
45 for (int i = 0; i < kNumIterations; ++i) { | |
46 LARGE_INTEGER qpc_now; | |
47 QueryPerformanceCounter(&qpc_now); | |
48 int delta = static_cast<int>(qpc_now.QuadPart - qpc_last.QuadPart); | |
49 if (delta != 0) { | |
50 min_delta = std::min(min_delta, delta); | |
51 } | |
52 qpc_last = qpc_now; | |
53 } | |
54 | |
55 UMA_HISTOGRAM_BOOLEAN("WinTimeTicks.NonDecreasing", min_delta > 0); | |
56 if (min_delta < 0) { | |
57 return; | |
jar (doing other things)
2013/04/04 00:26:13
I'm surprised you don't want a histogram of how of
James Simonsen
2013/04/04 02:26:51
Good point. Done.
| |
58 } | |
59 | |
60 int min_delta_us = static_cast<int>( | |
61 min_delta * (1e6 / qpc_frequency.QuadPart)); | |
62 UMA_HISTOGRAM_CUSTOM_COUNTS("WinTimeTicks.MinResolutionMicroseconds", | |
63 min_delta_us, 1, 1000, 50); | |
64 | |
65 bool success = min_delta_us <= 100; // Our goal is 0.1ms resolution. | |
66 if (success) { | |
67 UMA_HISTOGRAM_ENUMERATION("WinTimeTicks.VersionSuccessful", | |
68 info->version(), base::win::VERSION_WIN_LAST); | |
69 } | |
70 } | |
71 | |
72 } // namespace chrome_browser_net | |
73 | |
74 #endif // defined(OS_WIN) | |
OLD | NEW |