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
|
// Copyright 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "config.h"
#include "CCFrameRateCounter.h"
#include <cmath>
#include "CCProxy.h"
#include <public/Platform.h>
namespace cc {
const double CCFrameRateCounter::kFrameTooFast = 1.0 / 70.0; // measured in seconds
const double CCFrameRateCounter::kFrameTooSlow = 1.0 / 12.0;
const double CCFrameRateCounter::kDroppedFrameTime = 1.0 / 50.0;
// safeMod works on -1, returning m-1 in that case.
static inline int safeMod(int number, int modulus)
{
return (number + modulus) % modulus;
}
// static
scoped_ptr<CCFrameRateCounter> CCFrameRateCounter::create() {
return make_scoped_ptr(new CCFrameRateCounter());
}
inline base::TimeDelta CCFrameRateCounter::frameInterval(int frameNumber) const
{
return m_timeStampHistory[frameIndex(frameNumber)] -
m_timeStampHistory[frameIndex(frameNumber - 1)];
}
inline int CCFrameRateCounter::frameIndex(int frameNumber) const
{
return safeMod(frameNumber, kTimeStampHistorySize);
}
CCFrameRateCounter::CCFrameRateCounter()
: m_currentFrameNumber(1)
, m_droppedFrameCount(0)
{
m_timeStampHistory[0] = base::TimeTicks::Now();
m_timeStampHistory[1] = m_timeStampHistory[0];
for (int i = 2; i < kTimeStampHistorySize; i++)
m_timeStampHistory[i] = base::TimeTicks();
}
void CCFrameRateCounter::markBeginningOfFrame(base::TimeTicks timestamp)
{
m_timeStampHistory[frameIndex(m_currentFrameNumber)] = timestamp;
base::TimeDelta frameIntervalSeconds = frameInterval(m_currentFrameNumber);
if (CCProxy::hasImplThread() && m_currentFrameNumber > 0) {
double drawDelayMs = frameIntervalSeconds.InMillisecondsF();
WebKit::Platform::current()->histogramCustomCounts("Renderer4.CompositorThreadImplDrawDelay", static_cast<int>(drawDelayMs), 1, 120, 60);
}
if (!isBadFrameInterval(frameIntervalSeconds) &&
frameIntervalSeconds.InSecondsF() > kDroppedFrameTime)
++m_droppedFrameCount;
}
void CCFrameRateCounter::markEndOfFrame()
{
m_currentFrameNumber += 1;
}
bool CCFrameRateCounter::isBadFrameInterval(base::TimeDelta intervalBetweenConsecutiveFrames) const
{
bool schedulerAllowsDoubleFrames = !CCProxy::hasImplThread();
bool intervalTooFast = schedulerAllowsDoubleFrames && intervalBetweenConsecutiveFrames.InSecondsF() < kFrameTooFast;
bool intervalTooSlow = intervalBetweenConsecutiveFrames.InSecondsF() > kFrameTooSlow;
return intervalTooFast || intervalTooSlow;
}
bool CCFrameRateCounter::isBadFrame(int frameNumber) const
{
return isBadFrameInterval(frameInterval(frameNumber));
}
void CCFrameRateCounter::getAverageFPSAndStandardDeviation(double& averageFPS, double& standardDeviation) const
{
int frame = m_currentFrameNumber - 1;
averageFPS = 0;
int averageFPSCount = 0;
double fpsVarianceNumerator = 0;
// Walk backwards through the samples looking for a run of good frame
// timings from which to compute the mean and standard deviation.
//
// Slow frames occur just because the user is inactive, and should be
// ignored. Fast frames are ignored if the scheduler is in single-thread
// mode in order to represent the true frame rate in spite of the fact that
// the first few swapbuffers happen instantly which skews the statistics
// too much for short lived animations.
//
// isBadFrame encapsulates the frame too slow/frame too fast logic.
while (1) {
if (!isBadFrame(frame)) {
averageFPSCount++;
base::TimeDelta secForLastFrame = m_timeStampHistory[frameIndex(frame)] -
m_timeStampHistory[frameIndex(frame - 1)];
double x = 1.0 / secForLastFrame.InSecondsF();
double deltaFromAverage = x - averageFPS;
// Change with caution - numerics. http://en.wikipedia.org/wiki/Standard_deviation
averageFPS = averageFPS + deltaFromAverage / averageFPSCount;
fpsVarianceNumerator = fpsVarianceNumerator + deltaFromAverage * (x - averageFPS);
}
if (averageFPSCount && isBadFrame(frame)) {
// We've gathered a run of good samples, so stop.
break;
}
--frame;
if (frameIndex(frame) == frameIndex(m_currentFrameNumber) || frame < 0) {
// We've gone through all available historical data, so stop.
break;
}
}
standardDeviation = sqrt(fpsVarianceNumerator / averageFPSCount);
}
base::TimeTicks CCFrameRateCounter::timeStampOfRecentFrame(int n)
{
ASSERT(n >= 0 && n < kTimeStampHistorySize);
int desiredIndex = (frameIndex(m_currentFrameNumber) + n) % kTimeStampHistorySize;
return m_timeStampHistory[desiredIndex];
}
} // namespace cc
|
