1/* 2 * Copyright (c) 2002-2005 The Regents of The University of Michigan 3 * Copyright (c) 2011 Advanced Micro Devices 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions are 8 * met: redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer; 10 * redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution; 13 * neither the name of the copyright holders nor the names of its 14 * contributors may be used to endorse or promote products derived from 15 * this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 18 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 19 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 20 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 21 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 22 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 23 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 * 29 * Authors: Nathan Binkert 30 * Steve Reinhardt 31 * Gabe Black 32 */ 33 34#include "base/misc.hh" 35#include "sim/root.hh" 36 37Root *Root::_root = NULL; 38 39/* 40 * This function is called periodically by an event in M5 and ensures that 41 * at least as much real time has passed between invocations as simulated time. 42 * If not, the function either sleeps, or if the difference is small enough 43 * spin waits. 44 */ 45void 46Root::timeSync() 47{ 48 Time cur_time, diff, period = timeSyncPeriod(); 49 50 do { 51 cur_time.setTimer(); 52 diff = cur_time - lastTime; 53 Time remainder = period - diff; 54 if (diff < period && remainder > _spinThreshold) { 55 DPRINTF(TimeSync, "Sleeping to sync with real time.\n"); 56 // Sleep until the end of the period, or until a signal. 57 sleep(remainder); 58 // Refresh the current time. 59 cur_time.setTimer(); 60 } 61 } while (diff < period); 62 lastTime = cur_time; 63 schedule(&syncEvent, curTick() + _periodTick); 64} 65 66void 67Root::timeSyncEnable(bool en) 68{ 69 if (en == _enabled) 70 return; 71 _enabled = en; 72 if (_enabled) { 73 // Get event going. 74 Tick periods = ((curTick() + _periodTick - 1) / _periodTick); 75 Tick nextPeriod = periods * _periodTick; 76 schedule(&syncEvent, nextPeriod); 77 } else { 78 // Stop event. 79 deschedule(&syncEvent); 80 } 81} 82 83/// Configure the period for time sync events. 84void 85Root::timeSyncPeriod(Time newPeriod) 86{ 87 bool en = timeSyncEnabled(); 88 _period = newPeriod; 89 _periodTick = _period.getTick(); 90 timeSyncEnable(en); 91} 92 93/// Set the threshold for time remaining to spin wait. 94void 95Root::timeSyncSpinThreshold(Time newThreshold) 96{ 97 bool en = timeSyncEnabled(); 98 _spinThreshold = newThreshold; 99 timeSyncEnable(en); 100} 101 102Root::Root(RootParams *p) : SimObject(p), _enabled(false), 103 _periodTick(p->time_sync_period), syncEvent(this) 104{ 105 _period.setTick(p->time_sync_period); 106 _spinThreshold.setTick(p->time_sync_spin_threshold); 107 108 assert(_root == NULL); 109 _root = this; 110 lastTime.setTimer();
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