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#include "systemc/core/kernel.hh" 36#include "systemc/ext/core/sc_main.hh" 37 38namespace sc_gem5 39{ 40 41Scheduler::Scheduler() : 42 eq(nullptr), readyEvent(this, false, ReadyPriority), 43 pauseEvent(this, false, PausePriority), 44 stopEvent(this, false, StopPriority), 45 scMain(nullptr), 46 starvationEvent(this, false, StarvationPriority), 47 _started(false), _paused(false), _stopped(false), 48 maxTickEvent(this, false, MaxTickPriority), 49 _numCycles(0), _current(nullptr), initDone(false), 50 runOnce(false) 51{} 52 53void 54Scheduler::initPhase() 55{ 56 for (Process *p = toFinalize.getNext(); p; p = toFinalize.getNext()) { 57 p->finalize(); 58 p->popListNode(); 59 } 60 61 for (Process *p = initList.getNext(); p; p = initList.getNext()) { 62 p->finalize(); 63 p->popListNode(); 64 p->ready(); 65 } 66 67 update(); 68 69 for (auto &e: deltas) 70 e->run(); 71 deltas.clear(); 72 73 for (auto ets: eventsToSchedule) 74 eq->schedule(ets.first, ets.second); 75 eventsToSchedule.clear(); 76 77 if (_started) { 78 if (starved() && !runToTime) 79 scheduleStarvationEvent();
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80 eq->schedule(&maxTickEvent, maxTick);
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80 kernel->status(::sc_core::SC_RUNNING); |
81 } 82 83 initDone = true; 84} 85 86void 87Scheduler::reg(Process *p) 88{ 89 if (initDone) { 90 // If we're past initialization, finalize static sensitivity. 91 p->finalize(); 92 // Mark the process as ready. 93 p->ready(); 94 } else { 95 // Otherwise, record that this process should be initialized once we 96 // get there. 97 initList.pushLast(p); 98 } 99} 100 101void 102Scheduler::dontInitialize(Process *p) 103{ 104 if (initDone) { 105 // Pop this process off of the ready list. 106 p->popListNode(); 107 } else { 108 // Push this process onto the list of processes which still need 109 // their static sensitivity to be finalized. That implicitly pops it 110 // off the list of processes to be initialized/marked ready. 111 toFinalize.pushLast(p); 112 } 113} 114 115void 116Scheduler::yield() 117{ 118 _current = readyList.getNext(); 119 if (!_current) { 120 // There are no more processes, so return control to evaluate. 121 Fiber::primaryFiber()->run(); 122 } else { 123 _current->popListNode(); 124 // Switch to whatever Fiber is supposed to run this process. All 125 // Fibers which aren't running should be parked at this line. 126 _current->fiber()->run(); 127 // If the current process needs to be manually started, start it. 128 if (_current && _current->needsStart()) 129 _current->run(); 130 } 131 if (_current && _current->excWrapper) { 132 // Make sure this isn't a method process. 133 assert(!_current->needsStart()); 134 auto ew = _current->excWrapper; 135 _current->excWrapper = nullptr; 136 ew->throw_it(); 137 } 138} 139 140void 141Scheduler::ready(Process *p) 142{ 143 // Clump methods together to minimize context switching. 144 if (p->procKind() == ::sc_core::SC_METHOD_PROC_) 145 readyList.pushFirst(p); 146 else 147 readyList.pushLast(p); 148 149 scheduleReadyEvent(); 150} 151 152void 153Scheduler::requestUpdate(Channel *c) 154{ 155 updateList.pushLast(c);
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156 if (eq)
157 scheduleReadyEvent();
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156 scheduleReadyEvent(); |
157} 158 159void 160Scheduler::scheduleReadyEvent() 161{ 162 // Schedule the evaluate and update phases. 163 if (!readyEvent.scheduled()) {
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165 panic_if(!eq, "Need to schedule ready, but no event manager.\n");
166 eq->schedule(&readyEvent, eq->getCurTick());
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164 schedule(&readyEvent); |
165 if (starvationEvent.scheduled())
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168 eq->deschedule(&starvationEvent);
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166 deschedule(&starvationEvent); |
167 } 168} 169 170void 171Scheduler::scheduleStarvationEvent() 172{ 173 if (!starvationEvent.scheduled()) {
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176 Tick now = getCurTick();
177 if (initDone)
178 eq->schedule(&starvationEvent, now);
179 else
180 eventsToSchedule[&starvationEvent] = now;
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174 schedule(&starvationEvent); |
175 if (readyEvent.scheduled())
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182 eq->deschedule(&readyEvent);
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176 deschedule(&readyEvent); |
177 } 178} 179 180void 181Scheduler::runReady() 182{ 183 bool empty = readyList.empty(); 184 185 // The evaluation phase. 186 do { 187 yield(); 188 } while (!readyList.empty()); 189 190 if (!empty) 191 _numCycles++; 192 193 // The update phase. 194 update(); 195 196 if (starved() && !runToTime) 197 scheduleStarvationEvent(); 198 199 // The delta phase. 200 for (auto &e: deltas) 201 e->run(); 202 deltas.clear(); 203 204 if (runOnce) 205 schedulePause(); 206} 207 208void 209Scheduler::update() 210{ 211 Channel *channel = updateList.getNext(); 212 while (channel) { 213 channel->popListNode(); 214 channel->update(); 215 channel = updateList.getNext(); 216 } 217} 218 219void 220Scheduler::pause() 221{ 222 _paused = true; 223 kernel->status(::sc_core::SC_PAUSED); 224 runOnce = false; 225 scMain->run(); 226} 227 228void 229Scheduler::stop() 230{ 231 _stopped = true; 232 kernel->stop(); 233 runOnce = false; 234 scMain->run(); 235} 236 237void 238Scheduler::start(Tick max_tick, bool run_to_time) 239{ 240 // We should be running from sc_main. Keep track of that Fiber to return 241 // to later. 242 scMain = Fiber::currentFiber(); 243 244 _started = true; 245 _paused = false; 246 _stopped = false; 247 runToTime = run_to_time; 248 249 maxTick = max_tick; 250 251 if (initDone) { 252 if (starved() && !runToTime) 253 scheduleStarvationEvent(); 254 kernel->status(::sc_core::SC_RUNNING);
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261 eq->schedule(&maxTickEvent, maxTick);
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255 } 256
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257 schedule(&maxTickEvent, maxTick); 258 |
259 // Return to gem5 to let it run events, etc. 260 Fiber::primaryFiber()->run(); 261 262 if (pauseEvent.scheduled()) 263 eq->deschedule(&pauseEvent); 264 if (stopEvent.scheduled()) 265 eq->deschedule(&stopEvent); 266 if (maxTickEvent.scheduled()) 267 eq->deschedule(&maxTickEvent); 268 if (starvationEvent.scheduled()) 269 eq->deschedule(&starvationEvent); 270} 271 272void 273Scheduler::oneCycle() 274{ 275 runOnce = true; 276 start(::MaxTick, false); 277} 278 279void 280Scheduler::schedulePause() 281{ 282 if (pauseEvent.scheduled()) 283 return; 284 285 eq->schedule(&pauseEvent, eq->getCurTick()); 286} 287 288void 289Scheduler::scheduleStop(bool finish_delta) 290{ 291 if (stopEvent.scheduled()) 292 return; 293 294 if (!finish_delta) { 295 // If we're not supposed to finish the delta cycle, flush the list 296 // of ready processes, scheduled updates, and delta notifications. 297 Process *p; 298 while ((p = readyList.getNext())) 299 p->popListNode(); 300 Channel *c; 301 while ((c = updateList.getNext())) 302 c->popListNode(); 303 for (auto &e: deltas) 304 e->deschedule(); 305 deltas.clear(); 306 } 307 eq->schedule(&stopEvent, eq->getCurTick()); 308} 309 310Scheduler scheduler; 311 312} // namespace sc_gem5
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