scheduler.cc revision 12957:e54f9890363d
1/* 2 * Copyright 2018 Google, Inc. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions are 6 * met: redistributions of source code must retain the above copyright 7 * notice, this list of conditions and the following disclaimer; 8 * redistributions in binary form must reproduce the above copyright 9 * notice, this list of conditions and the following disclaimer in the 10 * documentation and/or other materials provided with the distribution; 11 * neither the name of the copyright holders nor the names of its 12 * contributors may be used to endorse or promote products derived from 13 * this software without specific prior written permission. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 18 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 19 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 20 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 21 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 25 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 * Authors: Gabe Black 28 */ 29 30#include "systemc/core/scheduler.hh" 31 32#include "base/fiber.hh" 33#include "base/logging.hh" 34#include "sim/eventq.hh" 35 36namespace sc_gem5 37{ 38 39Scheduler::Scheduler() : 40 eq(nullptr), readyEvent(this, false, EventBase::Default_Pri + 1), 41 _numCycles(0), _current(nullptr), initReady(false) 42{} 43 44void 45Scheduler::prepareForInit() 46{ 47 for (Process *p = toFinalize.getNext(); p; p = toFinalize.getNext()) { 48 p->finalize(); 49 p->popListNode(); 50 } 51 52 for (Process *p = initList.getNext(); p; p = initList.getNext()) { 53 p->finalize(); 54 ready(p); 55 } 56 57 initReady = true; 58} 59 60void 61Scheduler::reg(Process *p) 62{ 63 if (initReady) { 64 // If we're past initialization, finalize static sensitivity. 65 p->finalize(); 66 // Mark the process as ready. 67 ready(p); 68 } else { 69 // Otherwise, record that this process should be initialized once we 70 // get there. 71 initList.pushLast(p); 72 } 73} 74 75void 76Scheduler::dontInitialize(Process *p) 77{ 78 if (initReady) { 79 // Pop this process off of the ready list. 80 p->popListNode(); 81 } else { 82 // Push this process onto the list of processes which still need 83 // their static sensitivity to be finalized. That implicitly pops it 84 // off the list of processes to be initialized/marked ready. 85 toFinalize.pushLast(p); 86 } 87} 88 89void 90Scheduler::yield() 91{ 92 _current = readyList.getNext(); 93 if (!_current) { 94 // There are no more processes, so return control to evaluate. 95 Fiber::primaryFiber()->run(); 96 } else { 97 _current->popListNode(); 98 // Switch to whatever Fiber is supposed to run this process. All 99 // Fibers which aren't running should be parked at this line. 100 _current->fiber()->run(); 101 // If the current process hasn't been started yet, start it. This 102 // should always be true for methods, but may not be true for threads. 103 if (_current && !_current->running()) 104 _current->run(); 105 } 106} 107 108void 109Scheduler::ready(Process *p) 110{ 111 // Clump methods together to minimize context switching. 112 if (p->procKind() == ::sc_core::SC_METHOD_PROC_) 113 readyList.pushFirst(p); 114 else 115 readyList.pushLast(p); 116 117 scheduleReadyEvent(); 118} 119 120void 121Scheduler::requestUpdate(Channel *c) 122{ 123 updateList.pushLast(c); 124 scheduleReadyEvent(); 125} 126 127void 128Scheduler::scheduleReadyEvent() 129{ 130 // Schedule the evaluate and update phases. 131 if (!readyEvent.scheduled()) { 132 panic_if(!eq, "Need to schedule ready, but no event manager.\n"); 133 eq->schedule(&readyEvent, eq->getCurTick()); 134 } 135} 136 137void 138Scheduler::runReady() 139{ 140 bool empty = readyList.empty(); 141 142 // The evaluation phase. 143 do { 144 yield(); 145 } while (!readyList.empty()); 146 147 if (!empty) 148 _numCycles++; 149 150 // The update phase. 151 update(); 152 153 // The delta phase will happen naturally through the event queue. 154} 155 156void 157Scheduler::update() 158{ 159 Channel *channel = updateList.getNext(); 160 while (channel) { 161 channel->popListNode(); 162 channel->update(); 163 channel = updateList.getNext(); 164 } 165} 166 167Scheduler scheduler; 168 169} // namespace sc_gem5 170