scheduler.cc revision 13088:05763ab10391
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 53Scheduler::~Scheduler() 54{ 55 // Clear out everything that belongs to us to make sure nobody tries to 56 // clear themselves out after the scheduler goes away. 57 clear(); 58} 59 60void 61Scheduler::clear() 62{ 63 // Delta notifications. 64 for (auto &e: deltas) 65 e->deschedule(); 66 deltas.clear(); 67 68 // Timed notifications. 69 for (auto &tsp: timeSlots) { 70 TimeSlot *&ts = tsp.second; 71 for (auto &e: ts->events) 72 e->deschedule(); 73 deschedule(ts); 74 } 75 timeSlots.clear(); 76 77 // gem5 events. 78 if (readyEvent.scheduled()) 79 deschedule(&readyEvent); 80 if (pauseEvent.scheduled()) 81 deschedule(&pauseEvent); 82 if (stopEvent.scheduled()) 83 deschedule(&stopEvent); 84 if (starvationEvent.scheduled()) 85 deschedule(&starvationEvent); 86 if (maxTickEvent.scheduled()) 87 deschedule(&maxTickEvent); 88 89 Process *p; 90 while ((p = toFinalize.getNext())) 91 p->popListNode(); 92 while ((p = initList.getNext())) 93 p->popListNode(); 94 while ((p = readyList.getNext())) 95 p->popListNode(); 96 97 Channel *c; 98 while ((c = updateList.getNext())) 99 c->popListNode(); 100} 101 102void 103Scheduler::initPhase() 104{ 105 for (Process *p = toFinalize.getNext(); p; p = toFinalize.getNext()) { 106 p->finalize(); 107 p->popListNode(); 108 } 109 110 for (Process *p = initList.getNext(); p; p = initList.getNext()) { 111 p->finalize(); 112 p->popListNode(); 113 p->ready(); 114 } 115 116 update(); 117 118 for (auto &e: deltas) 119 e->run(); 120 deltas.clear(); 121 122 for (auto ets: eventsToSchedule) 123 eq->schedule(ets.first, ets.second); 124 eventsToSchedule.clear(); 125 126 if (_started) { 127 if (starved() && !runToTime) 128 scheduleStarvationEvent(); 129 kernel->status(::sc_core::SC_RUNNING); 130 } 131 132 initDone = true; 133} 134 135void 136Scheduler::reg(Process *p) 137{ 138 if (initDone) { 139 // If we're past initialization, finalize static sensitivity. 140 p->finalize(); 141 // Mark the process as ready. 142 p->ready(); 143 } else { 144 // Otherwise, record that this process should be initialized once we 145 // get there. 146 initList.pushLast(p); 147 } 148} 149 150void 151Scheduler::dontInitialize(Process *p) 152{ 153 if (initDone) { 154 // Pop this process off of the ready list. 155 p->popListNode(); 156 } else { 157 // Push this process onto the list of processes which still need 158 // their static sensitivity to be finalized. That implicitly pops it 159 // off the list of processes to be initialized/marked ready. 160 toFinalize.pushLast(p); 161 } 162} 163 164void 165Scheduler::yield() 166{ 167 _current = readyList.getNext(); 168 if (!_current) { 169 // There are no more processes, so return control to evaluate. 170 Fiber::primaryFiber()->run(); 171 } else { 172 _current->popListNode(); 173 // Switch to whatever Fiber is supposed to run this process. All 174 // Fibers which aren't running should be parked at this line. 175 _current->fiber()->run(); 176 // If the current process needs to be manually started, start it. 177 if (_current && _current->needsStart()) 178 _current->run(); 179 } 180 if (_current && _current->excWrapper) { 181 // Make sure this isn't a method process. 182 assert(!_current->needsStart()); 183 auto ew = _current->excWrapper; 184 _current->excWrapper = nullptr; 185 ew->throw_it(); 186 } 187} 188 189void 190Scheduler::ready(Process *p) 191{ 192 // Clump methods together to minimize context switching. 193 if (p->procKind() == ::sc_core::SC_METHOD_PROC_) 194 readyList.pushFirst(p); 195 else 196 readyList.pushLast(p); 197 198 scheduleReadyEvent(); 199} 200 201void 202Scheduler::requestUpdate(Channel *c) 203{ 204 updateList.pushLast(c); 205 scheduleReadyEvent(); 206} 207 208void 209Scheduler::scheduleReadyEvent() 210{ 211 // Schedule the evaluate and update phases. 212 if (!readyEvent.scheduled()) { 213 schedule(&readyEvent); 214 if (starvationEvent.scheduled()) 215 deschedule(&starvationEvent); 216 } 217} 218 219void 220Scheduler::scheduleStarvationEvent() 221{ 222 if (!starvationEvent.scheduled()) { 223 schedule(&starvationEvent); 224 if (readyEvent.scheduled()) 225 deschedule(&readyEvent); 226 } 227} 228 229void 230Scheduler::runReady() 231{ 232 bool empty = readyList.empty(); 233 234 // The evaluation phase. 235 do { 236 yield(); 237 } while (!readyList.empty()); 238 239 if (!empty) 240 _numCycles++; 241 242 // The update phase. 243 update(); 244 245 if (starved() && !runToTime) 246 scheduleStarvationEvent(); 247 248 // The delta phase. 249 for (auto &e: deltas) 250 e->run(); 251 deltas.clear(); 252 253 if (runOnce) 254 schedulePause(); 255} 256 257void 258Scheduler::update() 259{ 260 Channel *channel = updateList.getNext(); 261 while (channel) { 262 channel->popListNode(); 263 channel->update(); 264 channel = updateList.getNext(); 265 } 266} 267 268void 269Scheduler::pause() 270{ 271 _paused = true; 272 kernel->status(::sc_core::SC_PAUSED); 273 runOnce = false; 274 scMain->run(); 275} 276 277void 278Scheduler::stop() 279{ 280 _stopped = true; 281 kernel->stop(); 282 283 clear(); 284 285 runOnce = false; 286 scMain->run(); 287} 288 289void 290Scheduler::start(Tick max_tick, bool run_to_time) 291{ 292 // We should be running from sc_main. Keep track of that Fiber to return 293 // to later. 294 scMain = Fiber::currentFiber(); 295 296 _started = true; 297 _paused = false; 298 _stopped = false; 299 runToTime = run_to_time; 300 301 maxTick = max_tick; 302 303 if (initDone) { 304 if (starved() && !runToTime) 305 scheduleStarvationEvent(); 306 kernel->status(::sc_core::SC_RUNNING); 307 } 308 309 schedule(&maxTickEvent, maxTick); 310 311 // Return to gem5 to let it run events, etc. 312 Fiber::primaryFiber()->run(); 313 314 if (pauseEvent.scheduled()) 315 deschedule(&pauseEvent); 316 if (stopEvent.scheduled()) 317 deschedule(&stopEvent); 318 if (maxTickEvent.scheduled()) 319 deschedule(&maxTickEvent); 320 if (starvationEvent.scheduled()) 321 deschedule(&starvationEvent); 322} 323 324void 325Scheduler::oneCycle() 326{ 327 runOnce = true; 328 start(::MaxTick, false); 329} 330 331void 332Scheduler::schedulePause() 333{ 334 if (pauseEvent.scheduled()) 335 return; 336 337 schedule(&pauseEvent); 338} 339 340void 341Scheduler::scheduleStop(bool finish_delta) 342{ 343 if (stopEvent.scheduled()) 344 return; 345 346 if (!finish_delta) { 347 // If we're not supposed to finish the delta cycle, flush all 348 // pending activity. 349 clear(); 350 } 351 schedule(&stopEvent); 352} 353 354Scheduler scheduler; 355 356} // namespace sc_gem5 357