1 /*-------------------------------------------------------------------------
2 * drawElements Quality Program Tester Core
3 * ----------------------------------------
4 *
5 * Copyright 2014 The Android Open Source Project
6 *
7 * Licensed under the Apache License, Version 2.0 (the "License");
8 * you may not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 *
19 *//*!
20 * \file
21 * \brief CPU warm-up utility, used to counteract CPU throttling.
22 *//*--------------------------------------------------------------------*/
23
24 #include "tcuCPUWarmup.hpp"
25 #include "deDefs.hpp"
26 #include "deMath.h"
27 #include "deClock.h"
28
29 #include <algorithm>
30
31 namespace tcu
32 {
33
34 namespace warmupCPUInternal
35 {
36
37 volatile Dummy g_dummy;
38
39 };
40
41 template <typename T, int Size>
floatMedian(const T (& v)[Size])42 static inline float floatMedian (const T (&v)[Size])
43 {
44 T temp[Size];
45 for (int i = 0; i < Size; i++)
46 temp[i] = v[i];
47
48 std::sort(DE_ARRAY_BEGIN(temp), DE_ARRAY_END(temp));
49
50 return Size % 2 == 0
51 ? 0.5f * ((float)temp[Size/2-1] + (float)temp[Size/2])
52 : (float)temp[Size/2];
53 }
54
55 template <typename T, int Size>
floatRelativeMedianAbsoluteDeviation(const T (& v)[Size])56 static inline float floatRelativeMedianAbsoluteDeviation (const T (&v)[Size])
57 {
58 const float median = floatMedian(v);
59 float absoluteDeviations[Size];
60
61 for (int i = 0; i < Size; i++)
62 absoluteDeviations[i] = deFloatAbs((float)v[i] - median);
63
64 return floatMedian(absoluteDeviations) / median;
65 }
66
dummyComputation(float initial,int numIterations)67 static inline float dummyComputation (float initial, int numIterations)
68 {
69 float a = initial;
70 int b = 123;
71
72 for (int i = 0; i < numIterations; i++)
73 {
74 // Arbitrary computations.
75 for (int j = 0; j < 4; j++)
76 {
77 a = deFloatCos(a + (float)b);
78 b = (b + 63) % 107 + de::abs((int)(a*10.0f));
79 }
80 }
81
82 return a + (float)b;
83 }
84
warmupCPU(void)85 void warmupCPU (void)
86 {
87 float dummy = *warmupCPUInternal::g_dummy.m_v;
88 int computationSize = 1;
89
90 // Do a rough calibration for computationSize to get dummyComputation's running time above a certain threshold.
91 while (computationSize < 1<<30) // \note This condition is unlikely to be met. The "real" loop exit is the break below.
92 {
93 const float singleMeasurementThreshold = 10000.0f;
94 const int numMeasurements = 3;
95 deInt64 times[numMeasurements];
96
97 for (int i = 0; i < numMeasurements; i++)
98 {
99 const deUint64 startTime = deGetMicroseconds();
100 dummy = dummyComputation(dummy, computationSize);
101 times[i] = (deInt64)(deGetMicroseconds() - startTime);
102 }
103
104 if (floatMedian(times) >= singleMeasurementThreshold)
105 break;
106
107 computationSize *= 2;
108 }
109
110 // Do dummyComputations until running time seems stable enough.
111 {
112 const int maxNumMeasurements = 50;
113 const int numConsecutiveMeasurementsRequired = 5;
114 const float relativeMedianAbsoluteDeviationThreshold = 0.05f;
115 deInt64 latestTimes[numConsecutiveMeasurementsRequired];
116
117 for (int measurementNdx = 0;
118
119 measurementNdx < maxNumMeasurements &&
120 (measurementNdx < numConsecutiveMeasurementsRequired ||
121 floatRelativeMedianAbsoluteDeviation(latestTimes) > relativeMedianAbsoluteDeviationThreshold);
122
123 measurementNdx++)
124 {
125 const deUint64 startTime = deGetMicroseconds();
126 dummy = dummyComputation(dummy, computationSize);
127 latestTimes[measurementNdx % numConsecutiveMeasurementsRequired] = (deInt64)(deGetMicroseconds() - startTime);
128 }
129 }
130
131 *warmupCPUInternal::g_dummy.m_v = dummy;
132 }
133
134 } // tcu
135