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
|
// Copyright 2018 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.
#ifndef UI_LATENCY_STREAM_ANALYZER_H_
#define UI_LATENCY_STREAM_ANALYZER_H_
#include <cstdint>
#include <memory>
#include <vector>
#include "base/macros.h"
#include "base/trace_event/trace_event_argument.h"
#include "ui/latency/fixed_point.h"
#include "ui/latency/histograms.h"
#include "ui/latency/windowed_analyzer.h"
namespace ui {
// Used to communicate fraction of time the value of a metric was greater than
// or equal to the threshold.
struct ThresholdResult {
double threshold = 0.0;
double ge_fraction = 0.0;
};
namespace frame_metrics {
// The StreamAnalyzerClient interface is currently the same as
// WindowedAnalyzerClient and can rely on the same implementation.
using StreamAnalyzerClient = WindowedAnalyzerClient;
// Tracks the overall mean, RMS, and SMR for a metric and also owns
// the Histogram and WindowedAnalyzer.
class StreamAnalyzer {
public:
StreamAnalyzer(const StreamAnalyzerClient* client,
const SharedWindowedAnalyzerClient* shared_client,
std::vector<uint32_t> thresholds,
std::unique_ptr<Histogram> histogram);
~StreamAnalyzer();
// Resets all statistics and history.
void Reset();
// Resets the statistics without throwing away recent sample history in the
// WindowedAnalyzer.
void StartNewReportPeriod();
// To play well with the histogram range, |value| should be within the
// range [0,64000000]. If the units are milliseconds, that's 64 seconds.
// Otherwise, the histogram will clip the result.
// |weight| may be the duration the frame was active in microseconds
// or it may be 1 in case every frame is to be weighed equally.
void AddSample(const uint32_t value, const uint32_t weight);
// The mean, root-mean-squared, and squared-mean-root of all samples
// received since the last call to StartNewReportPeriod().
// The units are the same as the values added in AddSample().
double ComputeMean() const;
double ComputeRMS() const;
double ComputeSMR() const;
// StdDev calculates the standard deviation of all values in the stream.
// The units are the same as the values added in AddSample().
// The work to track this is the same as RMS, so we effectively get this for
// free. Given two of the Mean, RMS, and StdDev, we can calculate the third.
double ComputeStdDev() const;
// VarianceOfRoots calculates the variance of all square roots of values.
// The units end up being the same as the values added in AddSample().
// The work to track this is the same as SMR.
// Given two of the Mean, SMR, and VarianceOfRoots, we can calculate the
// third. Note: We don't track something like RootStdDevOfSquares since it
// would be difficult to track values raised to the fourth power.
// TODO(brianderon): Remove VarianceOfRoots if it's not useful.
double ComputeVarianceOfRoots() const;
// Thresholds returns a percentile for threshold values given to the
// constructor. This is useful for tracking improvements in really good
// sources, but it's dynamic range is limited, which prevents it from
// detecting improvements in sources where most of the frames are "bad".
std::vector<ThresholdResult> ComputeThresholds() const;
// CalculatePercentiles returns a value for certain percentiles.
// It is only an estimate, since the values are calculated from a histogram
// rather than from the entire history of actual values.
// This is useful for tracking improvements even in really bad sources
// since it's dynamic range includes all possible values.
PercentileResults ComputePercentiles() const;
// Expose the WindowedAnalyzer as const to make it's accessors
// available directly.
const WindowedAnalyzer& window() const { return windowed_analyzer_; }
std::unique_ptr<base::trace_event::ConvertableToTraceFormat> AsValue() const;
void AsValueInto(base::trace_event::TracedValue* state) const;
protected:
double VarianceHelper(double accum, double square_accum) const;
struct ThresholdState {
explicit ThresholdState(uint32_t value) : threshold(value) {}
void ResetAccumulators();
uint32_t threshold;
uint32_t ge_weight = 0;
uint32_t lt_weight = 0;
};
const StreamAnalyzerClient* const client_;
std::vector<ThresholdState> thresholds_;
std::unique_ptr<Histogram> histogram_;
WindowedAnalyzer windowed_analyzer_;
uint64_t total_weight_ = 0;
uint64_t accumulator_ = 0;
uint64_t root_accumulator_ = 0;
Accumulator96b square_accumulator_;
DISALLOW_COPY_AND_ASSIGN(StreamAnalyzer);
};
} // namespace frame_metrics
} // namespace ui
#endif // UI_LATENCY_STREAM_ANALYZER_H_
|
