simulate.cc revision 10762
1/* 2 * Copyright (c) 2006 The Regents of The University of Michigan 3 * Copyright (c) 2013 Advanced Micro Devices, Inc. 4 * Copyright (c) 2013 Mark D. Hill and David A. Wood 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions are 9 * met: redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer; 11 * redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution; 14 * neither the name of the copyright holders nor the names of its 15 * contributors may be used to endorse or promote products derived from 16 * this software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 * 30 * Authors: Nathan Binkert 31 * Steve Reinhardt 32 */ 33 34#include <mutex> 35#include <thread> 36 37#include "base/misc.hh" 38#include "base/pollevent.hh" 39#include "base/types.hh" 40#include "sim/async.hh" 41#include "sim/eventq_impl.hh" 42#include "sim/sim_events.hh" 43#include "sim/sim_exit.hh" 44#include "sim/simulate.hh" 45#include "sim/stat_control.hh" 46 47//! Mutex for handling async events. 48std::mutex asyncEventMutex; 49 50//! Global barrier for synchronizing threads entering/exiting the 51//! simulation loop. 52Barrier *threadBarrier; 53 54//! forward declaration 55Event *doSimLoop(EventQueue *); 56 57/** 58 * The main function for all subordinate threads (i.e., all threads 59 * other than the main thread). These threads start by waiting on 60 * threadBarrier. Once all threads have arrived at threadBarrier, 61 * they enter the simulation loop concurrently. When they exit the 62 * loop, they return to waiting on threadBarrier. This process is 63 * repeated until the simulation terminates. 64 */ 65static void 66thread_loop(EventQueue *queue) 67{ 68 while (true) { 69 threadBarrier->wait(); 70 doSimLoop(queue); 71 } 72} 73 74GlobalSimLoopExitEvent *simulate_limit_event = nullptr; 75 76/** Simulate for num_cycles additional cycles. If num_cycles is -1 77 * (the default), do not limit simulation; some other event must 78 * terminate the loop. Exported to Python via SWIG. 79 * @return The SimLoopExitEvent that caused the loop to exit. 80 */ 81GlobalSimLoopExitEvent * 82simulate(Tick num_cycles) 83{ 84 // The first time simulate() is called from the Python code, we need to 85 // create a thread for each of event queues referenced by the 86 // instantiated sim objects. 87 static bool threads_initialized = false; 88 static std::vector<std::thread *> threads; 89 90 if (!threads_initialized) { 91 threadBarrier = new Barrier(numMainEventQueues); 92 93 // the main thread (the one we're currently running on) 94 // handles queue 0, so we only need to allocate new threads 95 // for queues 1..N-1. We'll call these the "subordinate" threads. 96 for (uint32_t i = 1; i < numMainEventQueues; i++) { 97 threads.push_back(new std::thread(thread_loop, mainEventQueue[i])); 98 } 99 100 threads_initialized = true; 101 simulate_limit_event = 102 new GlobalSimLoopExitEvent(mainEventQueue[0]->getCurTick(), 103 "simulate() limit reached", 0); 104 } 105 106 inform("Entering event queue @ %d. Starting simulation...\n", curTick()); 107 108 if (num_cycles < MaxTick - curTick()) 109 num_cycles = curTick() + num_cycles; 110 else // counter would roll over or be set to MaxTick anyhow 111 num_cycles = MaxTick; 112 113 simulate_limit_event->reschedule(num_cycles); 114 115 GlobalSyncEvent *quantum_event = NULL; 116 if (numMainEventQueues > 1) { 117 if (simQuantum == 0) { 118 fatal("Quantum for multi-eventq simulation not specified"); 119 } 120 121 quantum_event = new GlobalSyncEvent(curTick() + simQuantum, simQuantum, 122 EventBase::Progress_Event_Pri, 0); 123 124 inParallelMode = true; 125 } 126 127 // all subordinate (created) threads should be waiting on the 128 // barrier; the arrival of the main thread here will satisfy the 129 // barrier, and all threads will enter doSimLoop in parallel 130 threadBarrier->wait(); 131 Event *local_event = doSimLoop(mainEventQueue[0]); 132 assert(local_event != NULL); 133 134 inParallelMode = false; 135 136 // locate the global exit event and return it to Python 137 BaseGlobalEvent *global_event = local_event->globalEvent(); 138 assert(global_event != NULL); 139 140 GlobalSimLoopExitEvent *global_exit_event = 141 dynamic_cast<GlobalSimLoopExitEvent *>(global_event); 142 assert(global_exit_event != NULL); 143 144 //! Delete the simulation quantum event. 145 if (quantum_event != NULL) { 146 quantum_event->deschedule(); 147 delete quantum_event; 148 } 149 150 return global_exit_event; 151} 152 153/** 154 * Test and clear the global async_event flag, such that each time the 155 * flag is cleared, only one thread returns true (and thus is assigned 156 * to handle the corresponding async event(s)). 157 */ 158static bool 159testAndClearAsyncEvent() 160{ 161 bool was_set = false; 162 asyncEventMutex.lock(); 163 164 if (async_event) { 165 was_set = true; 166 async_event = false; 167 } 168 169 asyncEventMutex.unlock(); 170 return was_set; 171} 172 173/** 174 * The main per-thread simulation loop. This loop is executed by all 175 * simulation threads (the main thread and the subordinate threads) in 176 * parallel. 177 */ 178Event * 179doSimLoop(EventQueue *eventq) 180{ 181 // set the per thread current eventq pointer 182 curEventQueue(eventq); 183 eventq->handleAsyncInsertions(); 184 185 while (1) { 186 // there should always be at least one event (the SimLoopExitEvent 187 // we just scheduled) in the queue 188 assert(!eventq->empty()); 189 assert(curTick() <= eventq->nextTick() && 190 "event scheduled in the past"); 191 192 if (async_event && testAndClearAsyncEvent()) { 193 // Take the event queue lock in case any of the service 194 // routines want to schedule new events. 195 std::lock_guard<EventQueue> lock(*eventq); 196 if (async_statdump || async_statreset) { 197 Stats::schedStatEvent(async_statdump, async_statreset); 198 async_statdump = false; 199 async_statreset = false; 200 } 201 202 if (async_io) { 203 async_io = false; 204 pollQueue.service(); 205 } 206 207 if (async_exit) { 208 async_exit = false; 209 exitSimLoop("user interrupt received"); 210 } 211 212 if (async_exception) { 213 async_exception = false; 214 return NULL; 215 } 216 } 217 218 Event *exit_event = eventq->serviceOne(); 219 if (exit_event != NULL) { 220 return exit_event; 221 } 222 } 223 224 // not reached... only exit is return on SimLoopExitEvent 225} 226