scheduler.cc revision 13145
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), _changeStamp(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 while (!deltas.empty()) 65 deltas.front()->deschedule(); 66 67 // Timed notifications. 68 for (auto &tsp: timeSlots) { 69 TimeSlot *&ts = tsp.second; 70 while (!ts->events.empty()) 71 ts->events.front()->deschedule(); 72 deschedule(ts); 73 } 74 timeSlots.clear(); 75 76 // gem5 events. 77 if (readyEvent.scheduled()) 78 deschedule(&readyEvent); 79 if (pauseEvent.scheduled()) 80 deschedule(&pauseEvent); 81 if (stopEvent.scheduled()) 82 deschedule(&stopEvent); 83 if (starvationEvent.scheduled()) 84 deschedule(&starvationEvent); 85 if (maxTickEvent.scheduled()) 86 deschedule(&maxTickEvent); 87 88 Process *p; 89 while ((p = toFinalize.getNext())) 90 p->popListNode(); 91 while ((p = initList.getNext())) 92 p->popListNode(); 93 while ((p = readyList.getNext())) 94 p->popListNode(); 95 96 Channel *c; 97 while ((c = updateList.getNext())) 98 c->popListNode(); 99} 100 101void 102Scheduler::initPhase() 103{ 104 for (Process *p = toFinalize.getNext(); p; p = toFinalize.getNext()) { 105 p->finalize(); 106 p->popListNode(); 107 } 108 109 for (Process *p = initList.getNext(); p; p = initList.getNext()) { 110 p->finalize(); 111 p->popListNode(); 112 p->ready(); 113 } 114 115 update(); 116 117 while (!deltas.empty()) 118 deltas.front()->run(); 119 120 for (auto ets: eventsToSchedule) 121 eq->schedule(ets.first, ets.second); 122 eventsToSchedule.clear(); 123 124 if (_started) { 125 if (!runToTime && starved()) 126 scheduleStarvationEvent(); 127 kernel->status(::sc_core::SC_RUNNING); 128 } 129 130 initDone = true; 131} 132 133void 134Scheduler::reg(Process *p) 135{ 136 if (initDone) { 137 // If we're past initialization, finalize static sensitivity. 138 p->finalize(); 139 // Mark the process as ready. 140 p->ready(); 141 } else { 142 // Otherwise, record that this process should be initialized once we 143 // get there. 144 initList.pushLast(p); 145 } 146} 147 148void 149Scheduler::dontInitialize(Process *p) 150{ 151 if (initDone) { 152 // Pop this process off of the ready list. 153 p->popListNode(); 154 } else { 155 // Push this process onto the list of processes which still need 156 // their static sensitivity to be finalized. That implicitly pops it 157 // off the list of processes to be initialized/marked ready. 158 toFinalize.pushLast(p); 159 } 160} 161 162void 163Scheduler::yield() 164{ 165 _current = readyList.getNext(); 166 if (!_current) { 167 // There are no more processes, so return control to evaluate. 168 Fiber::primaryFiber()->run(); 169 } else { 170 _current->popListNode(); 171 // Switch to whatever Fiber is supposed to run this process. All 172 // Fibers which aren't running should be parked at this line. 173 _current->fiber()->run(); 174 // If the current process needs to be manually started, start it. 175 if (_current && _current->needsStart()) { 176 _current->needsStart(false); 177 _current->run(); 178 } 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 static bool cluster_methods = false; 194 195 if (cluster_methods && p->procKind() == ::sc_core::SC_METHOD_PROC_) 196 readyList.pushFirst(p); 197 else 198 readyList.pushLast(p); 199 200 scheduleReadyEvent(); 201} 202 203void 204Scheduler::resume(Process *p) 205{ 206 if (initDone) 207 ready(p); 208 else 209 initList.pushLast(p); 210} 211 212bool 213Scheduler::suspend(Process *p) 214{ 215 if (initDone) { 216 // After initialization, the only list we can be on is the ready list. 217 bool was_ready = (p->nextListNode != nullptr); 218 p->popListNode(); 219 return was_ready; 220 } else { 221 bool was_ready = false; 222 // Check the ready list to see if we find this process. 223 ListNode *n = readyList.nextListNode; 224 while (n != &readyList) { 225 if (n == p) { 226 was_ready = true; 227 break; 228 } 229 } 230 if (was_ready) 231 toFinalize.pushLast(p); 232 return was_ready; 233 } 234} 235 236void 237Scheduler::requestUpdate(Channel *c) 238{ 239 updateList.pushLast(c); 240 scheduleReadyEvent(); 241} 242 243void 244Scheduler::scheduleReadyEvent() 245{ 246 // Schedule the evaluate and update phases. 247 if (!readyEvent.scheduled()) { 248 schedule(&readyEvent); 249 if (starvationEvent.scheduled()) 250 deschedule(&starvationEvent); 251 } 252} 253 254void 255Scheduler::scheduleStarvationEvent() 256{ 257 if (!starvationEvent.scheduled()) { 258 schedule(&starvationEvent); 259 if (readyEvent.scheduled()) 260 deschedule(&readyEvent); 261 } 262} 263 264void 265Scheduler::runReady() 266{ 267 bool empty = readyList.empty(); 268 lastReadyTick = getCurTick(); 269 270 // The evaluation phase. 271 do { 272 yield(); 273 } while (!readyList.empty()); 274 275 if (!empty) { 276 _numCycles++; 277 _changeStamp++; 278 } 279 280 // The update phase. 281 update(); 282 283 // The delta phase. 284 while (!deltas.empty()) 285 deltas.front()->run(); 286 287 if (!runToTime && starved()) 288 scheduleStarvationEvent(); 289 290 if (runOnce) 291 schedulePause(); 292} 293 294void 295Scheduler::update() 296{ 297 Channel *channel = updateList.getNext(); 298 while (channel) { 299 channel->popListNode(); 300 channel->update(); 301 channel = updateList.getNext(); 302 } 303} 304 305void 306Scheduler::pause() 307{ 308 _paused = true; 309 kernel->status(::sc_core::SC_PAUSED); 310 runOnce = false; 311 scMain->run(); 312} 313 314void 315Scheduler::stop() 316{ 317 _stopped = true; 318 kernel->stop(); 319 320 clear(); 321 322 runOnce = false; 323 scMain->run(); 324} 325 326void 327Scheduler::start(Tick max_tick, bool run_to_time) 328{ 329 // We should be running from sc_main. Keep track of that Fiber to return 330 // to later. 331 scMain = Fiber::currentFiber(); 332 333 _started = true; 334 _paused = false; 335 _stopped = false; 336 runToTime = run_to_time; 337 338 maxTick = max_tick; 339 lastReadyTick = getCurTick(); 340 341 if (initDone) { 342 if (!runToTime && starved()) 343 scheduleStarvationEvent(); 344 kernel->status(::sc_core::SC_RUNNING); 345 } 346 347 schedule(&maxTickEvent, maxTick); 348 349 // Return to gem5 to let it run events, etc. 350 Fiber::primaryFiber()->run(); 351 352 if (pauseEvent.scheduled()) 353 deschedule(&pauseEvent); 354 if (stopEvent.scheduled()) 355 deschedule(&stopEvent); 356 if (maxTickEvent.scheduled()) 357 deschedule(&maxTickEvent); 358 if (starvationEvent.scheduled()) 359 deschedule(&starvationEvent); 360} 361 362void 363Scheduler::oneCycle() 364{ 365 runOnce = true; 366 scheduleReadyEvent(); 367 start(::MaxTick, false); 368} 369 370void 371Scheduler::schedulePause() 372{ 373 if (pauseEvent.scheduled()) 374 return; 375 376 schedule(&pauseEvent); 377} 378 379void 380Scheduler::scheduleStop(bool finish_delta) 381{ 382 if (stopEvent.scheduled()) 383 return; 384 385 if (!finish_delta) { 386 // If we're not supposed to finish the delta cycle, flush all 387 // pending activity. 388 clear(); 389 } 390 schedule(&stopEvent); 391} 392 393Scheduler scheduler; 394 395} // namespace sc_gem5 396