Merge pull request #7494 from Morph1984/no-time-to-wait
native_clock: Wait for less time in EstimateRDTSCFrequency
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commit
f1f91ad468
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@ -15,26 +15,26 @@
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namespace Common {
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namespace Common {
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u64 EstimateRDTSCFrequency() {
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u64 EstimateRDTSCFrequency() {
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const auto milli_10 = std::chrono::milliseconds{10};
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// Discard the first result measuring the rdtsc.
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// get current time
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_mm_mfence();
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_mm_mfence();
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const u64 tscStart = __rdtsc();
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__rdtsc();
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const auto startTime = std::chrono::steady_clock::now();
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std::this_thread::sleep_for(std::chrono::milliseconds{1});
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// wait roughly 3 seconds
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while (true) {
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auto milli = std::chrono::duration_cast<std::chrono::milliseconds>(
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std::chrono::steady_clock::now() - startTime);
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if (milli.count() >= 3000)
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break;
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std::this_thread::sleep_for(milli_10);
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}
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const auto endTime = std::chrono::steady_clock::now();
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_mm_mfence();
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_mm_mfence();
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const u64 tscEnd = __rdtsc();
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__rdtsc();
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// calculate difference
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const u64 timer_diff =
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// Get the current time.
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std::chrono::duration_cast<std::chrono::nanoseconds>(endTime - startTime).count();
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const auto start_time = std::chrono::steady_clock::now();
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const u64 tsc_diff = tscEnd - tscStart;
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_mm_mfence();
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const u64 tsc_start = __rdtsc();
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// Wait for 200 milliseconds.
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std::this_thread::sleep_for(std::chrono::milliseconds{200});
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const auto end_time = std::chrono::steady_clock::now();
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_mm_mfence();
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const u64 tsc_end = __rdtsc();
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// Calculate differences.
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const u64 timer_diff = static_cast<u64>(
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std::chrono::duration_cast<std::chrono::nanoseconds>(end_time - start_time).count());
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const u64 tsc_diff = tsc_end - tsc_start;
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const u64 tsc_freq = MultiplyAndDivide64(tsc_diff, 1000000000ULL, timer_diff);
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const u64 tsc_freq = MultiplyAndDivide64(tsc_diff, 1000000000ULL, timer_diff);
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return tsc_freq;
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return tsc_freq;
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}
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}
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