scheduler.cc revision 13068:822c1be3550e
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(); 80 eq->schedule(&maxTickEvent, maxTick); 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); 156 if (eq) 157 scheduleReadyEvent(); 158} 159 160void 161Scheduler::scheduleReadyEvent() 162{ 163 // Schedule the evaluate and update phases. 164 if (!readyEvent.scheduled()) { 165 panic_if(!eq, "Need to schedule ready, but no event manager.\n"); 166 eq->schedule(&readyEvent, eq->getCurTick()); 167 if (starvationEvent.scheduled()) 168 eq->deschedule(&starvationEvent); 169 } 170} 171 172void 173Scheduler::scheduleStarvationEvent() 174{ 175 if (!starvationEvent.scheduled()) { 176 Tick now = getCurTick(); 177 if (initDone) 178 eq->schedule(&starvationEvent, now); 179 else 180 eventsToSchedule[&starvationEvent] = now; 181 if (readyEvent.scheduled()) 182 eq->deschedule(&readyEvent); 183 } 184} 185 186void 187Scheduler::runReady() 188{ 189 bool empty = readyList.empty(); 190 191 // The evaluation phase. 192 do { 193 yield(); 194 } while (!readyList.empty()); 195 196 if (!empty) 197 _numCycles++; 198 199 // The update phase. 200 update(); 201 202 if (starved() && !runToTime) 203 scheduleStarvationEvent(); 204 205 // The delta phase. 206 for (auto &e: deltas) 207 e->run(); 208 deltas.clear(); 209 210 if (runOnce) 211 schedulePause(); 212} 213 214void 215Scheduler::update() 216{ 217 Channel *channel = updateList.getNext(); 218 while (channel) { 219 channel->popListNode(); 220 channel->update(); 221 channel = updateList.getNext(); 222 } 223} 224 225void 226Scheduler::pause() 227{ 228 _paused = true; 229 kernel->status(::sc_core::SC_PAUSED); 230 runOnce = false; 231 scMain->run(); 232} 233 234void 235Scheduler::stop() 236{ 237 _stopped = true; 238 kernel->stop(); 239 runOnce = false; 240 scMain->run(); 241} 242 243void 244Scheduler::start(Tick max_tick, bool run_to_time) 245{ 246 // We should be running from sc_main. Keep track of that Fiber to return 247 // to later. 248 scMain = Fiber::currentFiber(); 249 250 _started = true; 251 _paused = false; 252 _stopped = false; 253 runToTime = run_to_time; 254 255 maxTick = max_tick; 256 257 if (initDone) { 258 if (starved() && !runToTime) 259 scheduleStarvationEvent(); 260 kernel->status(::sc_core::SC_RUNNING); 261 eq->schedule(&maxTickEvent, maxTick); 262 } 263 264 // Return to gem5 to let it run events, etc. 265 Fiber::primaryFiber()->run(); 266 267 if (pauseEvent.scheduled()) 268 eq->deschedule(&pauseEvent); 269 if (stopEvent.scheduled()) 270 eq->deschedule(&stopEvent); 271 if (maxTickEvent.scheduled()) 272 eq->deschedule(&maxTickEvent); 273 if (starvationEvent.scheduled()) 274 eq->deschedule(&starvationEvent); 275} 276 277void 278Scheduler::oneCycle() 279{ 280 runOnce = true; 281 start(::MaxTick, false); 282} 283 284void 285Scheduler::schedulePause() 286{ 287 if (pauseEvent.scheduled()) 288 return; 289 290 eq->schedule(&pauseEvent, eq->getCurTick()); 291} 292 293void 294Scheduler::scheduleStop(bool finish_delta) 295{ 296 if (stopEvent.scheduled()) 297 return; 298 299 if (!finish_delta) { 300 // If we're not supposed to finish the delta cycle, flush the list 301 // of ready processes, scheduled updates, and delta notifications. 302 Process *p; 303 while ((p = readyList.getNext())) 304 p->popListNode(); 305 Channel *c; 306 while ((c = updateList.getNext())) 307 c->popListNode(); 308 for (auto &e: deltas) 309 e->deschedule(); 310 deltas.clear(); 311 } 312 eq->schedule(&stopEvent, eq->getCurTick()); 313} 314 315Scheduler scheduler; 316 317} // namespace sc_gem5 318