scheduler.cc revision 12954:8ea3a185354c
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) 42{} 43 44void 45Scheduler::initToReady() 46{ 47 while (!initList.empty()) 48 ready(initList.getNext()); 49} 50 51void 52Scheduler::yield() 53{ 54 _current = readyList.getNext(); 55 if (!_current) { 56 // There are no more processes, so return control to evaluate. 57 Fiber::primaryFiber()->run(); 58 } else { 59 _current->popListNode(); 60 // Switch to whatever Fiber is supposed to run this process. All 61 // Fibers which aren't running should be parked at this line. 62 _current->fiber()->run(); 63 // If the current process hasn't been started yet, start it. This 64 // should always be true for methods, but may not be true for threads. 65 if (_current && !_current->running()) 66 _current->run(); 67 } 68} 69 70void 71Scheduler::ready(Process *p) 72{ 73 // Clump methods together to minimize context switching. 74 if (p->procKind() == ::sc_core::SC_METHOD_PROC_) 75 readyList.pushFirst(p); 76 else 77 readyList.pushLast(p); 78 79 scheduleReadyEvent(); 80} 81 82void 83Scheduler::requestUpdate(Channel *c) 84{ 85 updateList.pushLast(c); 86 scheduleReadyEvent(); 87} 88 89void 90Scheduler::scheduleReadyEvent() 91{ 92 // Schedule the evaluate and update phases. 93 if (!readyEvent.scheduled()) { 94 panic_if(!eq, "Need to schedule ready, but no event manager.\n"); 95 eq->schedule(&readyEvent, eq->getCurTick()); 96 } 97} 98 99void 100Scheduler::runReady() 101{ 102 bool empty = readyList.empty(); 103 104 // The evaluation phase. 105 do { 106 yield(); 107 } while (!readyList.empty()); 108 109 if (!empty) 110 _numCycles++; 111 112 // The update phase. 113 update(); 114 115 // The delta phase will happen naturally through the event queue. 116} 117 118void 119Scheduler::update() 120{ 121 Channel *channel = updateList.getNext(); 122 while (channel) { 123 channel->popListNode(); 124 channel->update(); 125 channel = updateList.getNext(); 126 } 127} 128 129Scheduler scheduler; 130 131} // namespace sc_gem5 132