scheduler.cc revision 13074:51b5e342f327
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 58 // Delta notifications. 59 for (auto &e: deltas) 60 e->deschedule(); 61 62 // Timed notifications. 63 for (auto &ts: timeSlots) { 64 for (auto &e: ts.second->events) 65 e->deschedule(); 66 delete ts.second; 67 ts.second = nullptr; 68 } 69 70 // gem5 events. 71 if (readyEvent.scheduled()) 72 eq->deschedule(&readyEvent); 73 if (pauseEvent.scheduled()) 74 eq->deschedule(&pauseEvent); 75 if (stopEvent.scheduled()) 76 eq->deschedule(&stopEvent); 77 if (starvationEvent.scheduled()) 78 eq->deschedule(&starvationEvent); 79 if (maxTickEvent.scheduled()) 80 eq->deschedule(&maxTickEvent); 81 82 Process *p; 83 while ((p = toFinalize.getNext())) 84 p->popListNode(); 85 while ((p = initList.getNext())) 86 p->popListNode(); 87 while ((p = readyList.getNext())) 88 p->popListNode(); 89 90 Channel *c; 91 while ((c = updateList.getNext())) 92 c->popListNode(); 93} 94 95void 96Scheduler::initPhase() 97{ 98 for (Process *p = toFinalize.getNext(); p; p = toFinalize.getNext()) { 99 p->finalize(); 100 p->popListNode(); 101 } 102 103 for (Process *p = initList.getNext(); p; p = initList.getNext()) { 104 p->finalize(); 105 p->popListNode(); 106 p->ready(); 107 } 108 109 update(); 110 111 for (auto &e: deltas) 112 e->run(); 113 deltas.clear(); 114 115 for (auto ets: eventsToSchedule) 116 eq->schedule(ets.first, ets.second); 117 eventsToSchedule.clear(); 118 119 if (_started) { 120 if (starved() && !runToTime) 121 scheduleStarvationEvent(); 122 kernel->status(::sc_core::SC_RUNNING); 123 } 124 125 initDone = true; 126} 127 128void 129Scheduler::reg(Process *p) 130{ 131 if (initDone) { 132 // If we're past initialization, finalize static sensitivity. 133 p->finalize(); 134 // Mark the process as ready. 135 p->ready(); 136 } else { 137 // Otherwise, record that this process should be initialized once we 138 // get there. 139 initList.pushLast(p); 140 } 141} 142 143void 144Scheduler::dontInitialize(Process *p) 145{ 146 if (initDone) { 147 // Pop this process off of the ready list. 148 p->popListNode(); 149 } else { 150 // Push this process onto the list of processes which still need 151 // their static sensitivity to be finalized. That implicitly pops it 152 // off the list of processes to be initialized/marked ready. 153 toFinalize.pushLast(p); 154 } 155} 156 157void 158Scheduler::yield() 159{ 160 _current = readyList.getNext(); 161 if (!_current) { 162 // There are no more processes, so return control to evaluate. 163 Fiber::primaryFiber()->run(); 164 } else { 165 _current->popListNode(); 166 // Switch to whatever Fiber is supposed to run this process. All 167 // Fibers which aren't running should be parked at this line. 168 _current->fiber()->run(); 169 // If the current process needs to be manually started, start it. 170 if (_current && _current->needsStart()) 171 _current->run(); 172 } 173 if (_current && _current->excWrapper) { 174 // Make sure this isn't a method process. 175 assert(!_current->needsStart()); 176 auto ew = _current->excWrapper; 177 _current->excWrapper = nullptr; 178 ew->throw_it(); 179 } 180} 181 182void 183Scheduler::ready(Process *p) 184{ 185 // Clump methods together to minimize context switching. 186 if (p->procKind() == ::sc_core::SC_METHOD_PROC_) 187 readyList.pushFirst(p); 188 else 189 readyList.pushLast(p); 190 191 scheduleReadyEvent(); 192} 193 194void 195Scheduler::requestUpdate(Channel *c) 196{ 197 updateList.pushLast(c); 198 scheduleReadyEvent(); 199} 200 201void 202Scheduler::scheduleReadyEvent() 203{ 204 // Schedule the evaluate and update phases. 205 if (!readyEvent.scheduled()) { 206 schedule(&readyEvent); 207 if (starvationEvent.scheduled()) 208 deschedule(&starvationEvent); 209 } 210} 211 212void 213Scheduler::scheduleStarvationEvent() 214{ 215 if (!starvationEvent.scheduled()) { 216 schedule(&starvationEvent); 217 if (readyEvent.scheduled()) 218 deschedule(&readyEvent); 219 } 220} 221 222void 223Scheduler::runReady() 224{ 225 bool empty = readyList.empty(); 226 227 // The evaluation phase. 228 do { 229 yield(); 230 } while (!readyList.empty()); 231 232 if (!empty) 233 _numCycles++; 234 235 // The update phase. 236 update(); 237 238 if (starved() && !runToTime) 239 scheduleStarvationEvent(); 240 241 // The delta phase. 242 for (auto &e: deltas) 243 e->run(); 244 deltas.clear(); 245 246 if (runOnce) 247 schedulePause(); 248} 249 250void 251Scheduler::update() 252{ 253 Channel *channel = updateList.getNext(); 254 while (channel) { 255 channel->popListNode(); 256 channel->update(); 257 channel = updateList.getNext(); 258 } 259} 260 261void 262Scheduler::pause() 263{ 264 _paused = true; 265 kernel->status(::sc_core::SC_PAUSED); 266 runOnce = false; 267 scMain->run(); 268} 269 270void 271Scheduler::stop() 272{ 273 _stopped = true; 274 kernel->stop(); 275 276 if (readyEvent.scheduled()) 277 eq->deschedule(&readyEvent); 278 279 runOnce = false; 280 scMain->run(); 281} 282 283void 284Scheduler::start(Tick max_tick, bool run_to_time) 285{ 286 // We should be running from sc_main. Keep track of that Fiber to return 287 // to later. 288 scMain = Fiber::currentFiber(); 289 290 _started = true; 291 _paused = false; 292 _stopped = false; 293 runToTime = run_to_time; 294 295 maxTick = max_tick; 296 297 if (initDone) { 298 if (starved() && !runToTime) 299 scheduleStarvationEvent(); 300 kernel->status(::sc_core::SC_RUNNING); 301 } 302 303 schedule(&maxTickEvent, maxTick); 304 305 // Return to gem5 to let it run events, etc. 306 Fiber::primaryFiber()->run(); 307 308 if (pauseEvent.scheduled()) 309 eq->deschedule(&pauseEvent); 310 if (stopEvent.scheduled()) 311 eq->deschedule(&stopEvent); 312 if (maxTickEvent.scheduled()) 313 eq->deschedule(&maxTickEvent); 314 if (starvationEvent.scheduled()) 315 eq->deschedule(&starvationEvent); 316} 317 318void 319Scheduler::oneCycle() 320{ 321 runOnce = true; 322 start(::MaxTick, false); 323} 324 325void 326Scheduler::schedulePause() 327{ 328 if (pauseEvent.scheduled()) 329 return; 330 331 eq->schedule(&pauseEvent, eq->getCurTick()); 332} 333 334void 335Scheduler::scheduleStop(bool finish_delta) 336{ 337 if (stopEvent.scheduled()) 338 return; 339 340 if (!finish_delta) { 341 // If we're not supposed to finish the delta cycle, flush the list 342 // of ready processes, scheduled updates, and delta notifications. 343 Process *p; 344 while ((p = readyList.getNext())) 345 p->popListNode(); 346 Channel *c; 347 while ((c = updateList.getNext())) 348 c->popListNode(); 349 for (auto &e: deltas) 350 e->deschedule(); 351 deltas.clear(); 352 } 353 eq->schedule(&stopEvent, eq->getCurTick()); 354} 355 356Scheduler scheduler; 357 358} // namespace sc_gem5 359