Sean Keely
4e9849034d
Each time delay is grown we need to reset elapsed. We want to take the most accurate sample from the set at fixed delay. Without this we will hang if there is ever an insufficiently accurate, high unit clock read. Change-Id: Ic65f364067789ac85a6572d67af2d77528e265bb
112 строки
4.1 KiB
C++
112 строки
4.1 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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//
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// The University of Illinois/NCSA
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// Open Source License (NCSA)
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//
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// Copyright (c) 2014-2020, Advanced Micro Devices, Inc. All rights reserved.
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//
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// Developed by:
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//
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// AMD Research and AMD HSA Software Development
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//
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// Advanced Micro Devices, Inc.
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//
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// www.amd.com
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to
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// deal with the Software without restriction, including without limitation
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// the rights to use, copy, modify, merge, publish, distribute, sublicense,
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// and/or sell copies of the Software, and to permit persons to whom the
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// Software is furnished to do so, subject to the following conditions:
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//
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// - Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimers.
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// - Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimers in
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// the documentation and/or other materials provided with the distribution.
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// - Neither the names of Advanced Micro Devices, Inc,
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// nor the names of its contributors may be used to endorse or promote
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// products derived from this Software without specific prior written
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// permission.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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// THE CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
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// OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS WITH THE SOFTWARE.
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//
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////////////////////////////////////////////////////////////////////////////////
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#include "core/util/timer.h"
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namespace rocr {
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namespace timer {
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accurate_clock::init::init() {
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freq = os::AccurateClockFrequency();
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accurate_clock::period_ns = 1e9 / double(freq);
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}
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// Calibrates the fast clock using the accurate clock.
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fast_clock::init::init() {
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typedef accurate_clock clock;
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clock::duration delay(std::chrono::milliseconds(1));
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// calibrate clock
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fast_clock::raw_rep min = 0;
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clock::duration elapsed;
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do {
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elapsed = clock::duration::max();
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for (int t = 0; t < 10; t++) {
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fast_clock::raw_rep r1, r2;
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clock::time_point t0, t1, t2, t3;
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t0 = clock::now();
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std::atomic_signal_fence(std::memory_order_acq_rel);
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r1 = fast_clock::raw_now();
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std::atomic_signal_fence(std::memory_order_acq_rel);
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t1 = clock::now();
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std::atomic_signal_fence(std::memory_order_acq_rel);
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do {
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t2 = clock::now();
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} while (t2 - t1 < delay);
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std::atomic_signal_fence(std::memory_order_acq_rel);
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r2 = fast_clock::raw_now();
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std::atomic_signal_fence(std::memory_order_acq_rel);
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t3 = clock::now();
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// If elapsed time is shorter than last recorded time and both the start
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// and end times are confirmed correlated then record the clock readings.
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// This protects against inaccuracy due to thread switching
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if ((t3 - t1 < elapsed) && ((t1 - t0) * 10 < (t2 - t1)) &&
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((t3 - t2) * 10 < (t2 - t1))) {
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elapsed = t3 - t1;
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min = r2 - r1;
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}
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}
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delay += delay;
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} while (min < 1000);
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fast_clock::freq = double(min) / duration_in_seconds(elapsed);
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fast_clock::period_ps = 1e12 / fast_clock::freq;
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// printf("Timer setup took %f ms\n", duration_in_seconds(elapsed)*1000.0f);
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// printf("Fast clock frequency: %f MHz\n", double(fast_clock::freq)/1e6);
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}
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double accurate_clock::period_ns;
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accurate_clock::raw_frequency accurate_clock::freq;
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accurate_clock::init accurate_clock::accurate_clock_init;
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double fast_clock::period_ps;
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fast_clock::raw_frequency fast_clock::freq;
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fast_clock::init fast_clock::fast_clock_init;
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} // namespace timer
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} // namespace rocr
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