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40 | ****************************************************************************/ |
41 | |
42 | #include "qtconcurrentiteratekernel.h" |
43 | |
44 | #if defined(Q_OS_MAC) |
45 | #include <mach/mach.h> |
46 | #include <mach/mach_time.h> |
47 | #include <unistd.h> |
48 | #elif defined(Q_OS_UNIX) |
49 | #if defined(Q_OS_HURD) |
50 | #include <sys/time.h> |
51 | #endif |
52 | #include <time.h> |
53 | #include <unistd.h> |
54 | #elif defined(Q_OS_WIN) |
55 | #include <qt_windows.h> |
56 | #endif |
57 | |
58 | #include "private/qfunctions_p.h" |
59 | |
60 | |
61 | #ifndef QT_NO_CONCURRENT |
62 | |
63 | QT_BEGIN_NAMESPACE |
64 | |
65 | enum { |
66 | TargetRatio = 100, |
67 | MedianSize = 7 |
68 | }; |
69 | |
70 | #if defined(Q_OS_MAC) |
71 | |
72 | static qint64 getticks() |
73 | { |
74 | return mach_absolute_time(); |
75 | } |
76 | |
77 | #elif defined(Q_OS_UNIX) |
78 | |
79 | |
80 | static qint64 getticks() |
81 | { |
82 | #if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) |
83 | clockid_t clockId; |
84 | |
85 | #ifndef _POSIX_THREAD_CPUTIME |
86 | clockId = CLOCK_REALTIME; |
87 | #elif (_POSIX_THREAD_CPUTIME-0 <= 0) |
88 | // if we don't have CLOCK_THREAD_CPUTIME_ID, we have to just use elapsed realtime instead |
89 | clockId = CLOCK_REALTIME; |
90 | |
91 | # if (_POSIX_THREAD_CPUTIME-0 == 0) |
92 | // detect availablility of CLOCK_THREAD_CPUTIME_ID |
93 | static long useThreadCpuTime = -2; |
94 | if (useThreadCpuTime == -2) { |
95 | // sysconf() will return either -1 or _POSIX_VERSION (don't care about thread races here) |
96 | useThreadCpuTime = sysconf(_SC_THREAD_CPUTIME); |
97 | } |
98 | if (useThreadCpuTime != -1) |
99 | clockId = CLOCK_THREAD_CPUTIME_ID; |
100 | # endif |
101 | #else |
102 | clockId = CLOCK_THREAD_CPUTIME_ID; |
103 | #endif |
104 | |
105 | struct timespec ts; |
106 | if (clock_gettime(clockId, &ts) == -1) |
107 | return 0; |
108 | return (ts.tv_sec * 1000000000) + ts.tv_nsec; |
109 | #else |
110 | |
111 | #ifdef Q_OS_SYMBIAN |
112 | return clock(); |
113 | #else |
114 | // no clock_gettime(), fall back to wall time |
115 | struct timeval tv; |
116 | gettimeofday(&tv, 0); |
117 | return (tv.tv_sec * 1000000) + tv.tv_usec; |
118 | #endif |
119 | |
120 | #endif |
121 | } |
122 | |
123 | #elif defined(Q_OS_WIN) |
124 | |
125 | static qint64 getticks() |
126 | { |
127 | LARGE_INTEGER x; |
128 | if (!QueryPerformanceCounter(&x)) |
129 | return 0; |
130 | return x.QuadPart; |
131 | } |
132 | |
133 | #endif |
134 | |
135 | static double elapsed(qint64 after, qint64 before) |
136 | { |
137 | return double(after - before); |
138 | } |
139 | |
140 | namespace QtConcurrent { |
141 | |
142 | /*! \internal |
143 | |
144 | */ |
145 | BlockSizeManager::BlockSizeManager(int iterationCount) |
146 | : maxBlockSize(iterationCount / (QThreadPool::globalInstance()->maxThreadCount() * 2)), |
147 | beforeUser(0), afterUser(0), |
148 | controlPartElapsed(MedianSize), userPartElapsed(MedianSize), |
149 | m_blockSize(1) |
150 | { } |
151 | |
152 | // Records the time before user code. |
153 | void BlockSizeManager::timeBeforeUser() |
154 | { |
155 | if (blockSizeMaxed()) |
156 | return; |
157 | |
158 | beforeUser = getticks(); |
159 | controlPartElapsed.addValue(elapsed(beforeUser, afterUser)); |
160 | } |
161 | |
162 | // Records the time after user code and adjust the block size if we are spending |
163 | // to much time in the for control code compared with the user code. |
164 | void BlockSizeManager::timeAfterUser() |
165 | { |
166 | if (blockSizeMaxed()) |
167 | return; |
168 | |
169 | afterUser = getticks(); |
170 | userPartElapsed.addValue(elapsed(afterUser, beforeUser)); |
171 | |
172 | if (controlPartElapsed.isMedianValid() == false) |
173 | return; |
174 | |
175 | if (controlPartElapsed.median() * TargetRatio < userPartElapsed.median()) |
176 | return; |
177 | |
178 | m_blockSize = qMin(m_blockSize * 2, maxBlockSize); |
179 | |
180 | #ifdef QTCONCURRENT_FOR_DEBUG |
181 | qDebug() << QThread::currentThread() << "adjusting block size" << controlPartElapsed.median() << userPartElapsed.median() << m_blockSize; |
182 | #endif |
183 | |
184 | // Reset the medians after adjusting the block size so we get |
185 | // new measurements with the new block size. |
186 | controlPartElapsed.reset(); |
187 | userPartElapsed.reset(); |
188 | } |
189 | |
190 | int BlockSizeManager::blockSize() |
191 | { |
192 | return m_blockSize; |
193 | } |
194 | |
195 | } // namespace QtConcurrent |
196 | |
197 | QT_END_NAMESPACE |
198 | |
199 | #endif // QT_NO_CONCURRENT |
200 | |