root.cc revision 8332
1/* 2 * Copyright (c) 2002-2005 The Regents of The University of Michigan 3 * Copyright (c) 2011 Advanced Micro Devices, Inc. 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 "debug/TimeSync.hh" 36#include "sim/root.hh" 37 38Root *Root::_root = NULL; 39 40/* 41 * This function is called periodically by an event in M5 and ensures that 42 * at least as much real time has passed between invocations as simulated time. 43 * If not, the function either sleeps, or if the difference is small enough 44 * spin waits. 45 */ 46void 47Root::timeSync() 48{ 49 Time cur_time, diff, period = timeSyncPeriod(); 50 51 do { 52 cur_time.setTimer(); 53 diff = cur_time - lastTime; 54 Time remainder = period - diff; 55 if (diff < period && remainder > _spinThreshold) { 56 DPRINTF(TimeSync, "Sleeping to sync with real time.\n"); 57 // Sleep until the end of the period, or until a signal. 58 sleep(remainder); 59 // Refresh the current time. 60 cur_time.setTimer(); 61 } 62 } while (diff < period); 63 lastTime = cur_time; 64 schedule(&syncEvent, curTick() + _periodTick); 65} 66 67void 68Root::timeSyncEnable(bool en) 69{ 70 if (en == _enabled) 71 return; 72 _enabled = en; 73 if (_enabled) { 74 // Get event going. 75 Tick periods = ((curTick() + _periodTick - 1) / _periodTick); 76 Tick nextPeriod = periods * _periodTick; 77 schedule(&syncEvent, nextPeriod); 78 } else { 79 // Stop event. 80 deschedule(&syncEvent); 81 } 82} 83 84/// Configure the period for time sync events. 85void 86Root::timeSyncPeriod(Time newPeriod) 87{ 88 bool en = timeSyncEnabled(); 89 _period = newPeriod; 90 _periodTick = _period.getTick(); 91 timeSyncEnable(en); 92} 93 94/// Set the threshold for time remaining to spin wait. 95void 96Root::timeSyncSpinThreshold(Time newThreshold) 97{ 98 bool en = timeSyncEnabled(); 99 _spinThreshold = newThreshold; 100 timeSyncEnable(en); 101} 102 103Root::Root(RootParams *p) : SimObject(p), _enabled(false), 104 _periodTick(p->time_sync_period), syncEvent(this) 105{ 106 _period.setTick(p->time_sync_period); 107 _spinThreshold.setTick(p->time_sync_spin_threshold); 108 109 assert(_root == NULL); 110 _root = this; 111 lastTime.setTimer(); 112} 113 114void 115Root::initState() 116{ 117 timeSyncEnable(params()->time_sync_enable); 118} 119 120void 121Root::loadState(Checkpoint *cp) 122{ 123 timeSyncEnable(params()->time_sync_enable); 124} 125 126Root * 127RootParams::create() 128{ 129 static bool created = false; 130 if (created) 131 panic("only one root object allowed!"); 132 133 created = true; 134 135 return new Root(this); 136} 137