Evgeny
65 строки
1.5 KiB
C++
65 строки
1.5 KiB
C++
#ifndef _CORE_TIMER_H_
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#define _CORE_TIMER_H_
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template <int Size>
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class CoreTimer {
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CoreTimer() {
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index_ = 0;
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freq_in_100mhz_ = MeasureTSCFreqHz();
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}
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~CoreTimer() {
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if (index_ >= Size) {
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printf("ERROR: memory corruption: out of timer data");
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abort();
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}
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}
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// retrieve time
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double Get() {
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double n = 0;
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// AMD Linux timing
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unsigned int unused;
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n = __rdtscp(&unused);
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data_[index_] = 10 * n / freq_in_100mhz_; // unit is ns
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index_ += 1;
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}
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double Print()
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private:
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// timer data
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double data_[Size];
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// data index
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uint32_t index_;
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// frequency
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double freq_in_100mhz_;
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// timing methods
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uint64_t CoreTimer::CoarseTimestampUs() {
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struct timespec ts;
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clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
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return uint64_t(ts.tv_sec) * 1000000 + ts.tv_nsec / 1000;
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}
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uint64_t CoreTimer::MeasureTSCFreqHz() {
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// Make a coarse interval measurement of TSC ticks for 1 gigacycles.
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unsigned int unused;
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uint64_t tscTicksEnd;
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uint64_t coarseBeginUs = CoarseTimestampUs();
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uint64_t tscTicksBegin = __rdtscp(&unused);
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do {
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tscTicksEnd = __rdtscp(&unused);
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} while (tscTicksEnd - tscTicksBegin < 1000000000);
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uint64_t coarseEndUs = CoarseTimestampUs();
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// Compute the TSC frequency and round to nearest 100MHz.
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uint64_t coarseIntervalNs = (coarseEndUs - coarseBeginUs) * 1000;
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uint64_t tscIntervalTicks = tscTicksEnd - tscTicksBegin;
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return (tscIntervalTicks * 10 + (coarseIntervalNs / 2)) / coarseIntervalNs;
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}
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};
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#endif // _CORE_TIMER_H_
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