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),
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49 _numCycles(0), _current(nullptr), initReady(false),
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49 _numCycles(0), _current(nullptr), initDone(false), |
50 runOnce(false) 51{} 52 53void
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54Scheduler::prepareForInit()
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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
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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 eq->schedule(&maxTickEvent, maxTick); 79
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74 initReady = true;
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80 initDone = true; |
81} 82 83void 84Scheduler::reg(Process *p) 85{
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80 if (initReady) {
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86 if (initDone) { |
87 // If we're past initialization, finalize static sensitivity. 88 p->finalize(); 89 // Mark the process as ready. 90 p->ready(); 91 } else { 92 // Otherwise, record that this process should be initialized once we 93 // get there. 94 initList.pushLast(p); 95 } 96} 97 98void 99Scheduler::dontInitialize(Process *p) 100{
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95 if (initReady) {
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101 if (initDone) { |
102 // Pop this process off of the ready list. 103 p->popListNode(); 104 } else { 105 // Push this process onto the list of processes which still need 106 // their static sensitivity to be finalized. That implicitly pops it 107 // off the list of processes to be initialized/marked ready. 108 toFinalize.pushLast(p); 109 } 110} 111 112void 113Scheduler::yield() 114{ 115 _current = readyList.getNext(); 116 if (!_current) { 117 // There are no more processes, so return control to evaluate. 118 Fiber::primaryFiber()->run(); 119 } else { 120 _current->popListNode(); 121 // Switch to whatever Fiber is supposed to run this process. All 122 // Fibers which aren't running should be parked at this line. 123 _current->fiber()->run(); 124 // If the current process needs to be manually started, start it. 125 if (_current && _current->needsStart()) 126 _current->run(); 127 } 128 if (_current && _current->excWrapper) { 129 // Make sure this isn't a method process. 130 assert(!_current->needsStart()); 131 auto ew = _current->excWrapper; 132 _current->excWrapper = nullptr; 133 ew->throw_it(); 134 } 135} 136 137void 138Scheduler::ready(Process *p) 139{ 140 // Clump methods together to minimize context switching. 141 if (p->procKind() == ::sc_core::SC_METHOD_PROC_) 142 readyList.pushFirst(p); 143 else 144 readyList.pushLast(p); 145 146 scheduleReadyEvent(); 147} 148 149void 150Scheduler::requestUpdate(Channel *c) 151{ 152 updateList.pushLast(c); 153 if (eq) 154 scheduleReadyEvent(); 155} 156 157void 158Scheduler::scheduleReadyEvent() 159{ 160 // Schedule the evaluate and update phases. 161 if (!readyEvent.scheduled()) { 162 panic_if(!eq, "Need to schedule ready, but no event manager.\n"); 163 eq->schedule(&readyEvent, eq->getCurTick()); 164 if (starvationEvent.scheduled()) 165 eq->deschedule(&starvationEvent); 166 } 167} 168 169void 170Scheduler::scheduleStarvationEvent() 171{ 172 if (!starvationEvent.scheduled()) { 173 panic_if(!eq, "Need to schedule starvation event, " 174 "but no event manager.\n"); 175 eq->schedule(&starvationEvent, eq->getCurTick()); 176 if (readyEvent.scheduled()) 177 eq->deschedule(&readyEvent); 178 } 179} 180 181void 182Scheduler::runReady() 183{ 184 bool empty = readyList.empty(); 185 186 // The evaluation phase. 187 do { 188 yield(); 189 } while (!readyList.empty()); 190 191 if (!empty) 192 _numCycles++; 193 194 // The update phase. 195 update(); 196 197 if (starved() && !runToTime) 198 scheduleStarvationEvent(); 199 200 // The delta phase. 201 for (auto &e: deltas) 202 e->run(); 203 deltas.clear(); 204 205 if (runOnce) 206 schedulePause(); 207} 208 209void 210Scheduler::update() 211{ 212 Channel *channel = updateList.getNext(); 213 while (channel) { 214 channel->popListNode(); 215 channel->update(); 216 channel = updateList.getNext(); 217 } 218} 219 220void 221Scheduler::pause() 222{ 223 _paused = true; 224 kernel->status(::sc_core::SC_PAUSED); 225 runOnce = false; 226 scMain->run(); 227} 228 229void 230Scheduler::stop() 231{ 232 _stopped = true; 233 kernel->stop(); 234 runOnce = false; 235 scMain->run(); 236} 237 238void 239Scheduler::start(Tick max_tick, bool run_to_time) 240{ 241 // We should be running from sc_main. Keep track of that Fiber to return 242 // to later. 243 scMain = Fiber::currentFiber(); 244 245 _started = true; 246 _paused = false; 247 _stopped = false; 248 runToTime = run_to_time; 249 250 maxTick = max_tick; 251 252 if (starved() && !runToTime) 253 return; 254
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249 if (initReady) {
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255 if (initDone) { |
256 kernel->status(::sc_core::SC_RUNNING); 257 eq->schedule(&maxTickEvent, maxTick); 258 } 259 260 // Return to gem5 to let it run events, etc. 261 Fiber::primaryFiber()->run(); 262 263 if (pauseEvent.scheduled()) 264 eq->deschedule(&pauseEvent); 265 if (stopEvent.scheduled()) 266 eq->deschedule(&stopEvent); 267 if (maxTickEvent.scheduled()) 268 eq->deschedule(&maxTickEvent); 269 if (starvationEvent.scheduled()) 270 eq->deschedule(&starvationEvent); 271} 272 273void 274Scheduler::oneCycle() 275{ 276 runOnce = true; 277 start(::MaxTick, false); 278} 279 280void 281Scheduler::schedulePause() 282{ 283 if (pauseEvent.scheduled()) 284 return; 285 286 eq->schedule(&pauseEvent, eq->getCurTick()); 287} 288 289void 290Scheduler::scheduleStop(bool finish_delta) 291{ 292 if (stopEvent.scheduled()) 293 return; 294 295 if (!finish_delta) { 296 // If we're not supposed to finish the delta cycle, flush the list 297 // of ready processes, scheduled updates, and delta notifications. 298 Process *p; 299 while ((p = readyList.getNext())) 300 p->popListNode(); 301 Channel *c; 302 while ((c = updateList.getNext())) 303 c->popListNode(); 304 for (auto &e: deltas) 305 e->deschedule(); 306 deltas.clear(); 307 } 308 eq->schedule(&stopEvent, eq->getCurTick()); 309} 310 311Scheduler scheduler; 312 313} // namespace sc_gem5
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