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#include "systemc/ext/utils/sc_report.hh"
38#include "systemc/ext/utils/sc_report_handler.hh"
39
40namespace sc_gem5
41{
42
43Scheduler::Scheduler() :
44 eq(nullptr), readyEvent(this, false, ReadyPriority),
45 pauseEvent(this, false, PausePriority),
46 stopEvent(this, false, StopPriority),
45 scMain(nullptr),
47 scMain(nullptr), _throwToScMain(nullptr),
48 starvationEvent(this, false, StarvationPriority),
49 _started(false), _paused(false), _stopped(false), _stopNow(false),
50 maxTickEvent(this, false, MaxTickPriority),
51 _numCycles(0), _changeStamp(0), _current(nullptr), initDone(false),
52 runOnce(false), readyList(nullptr)
53{}
54
55Scheduler::~Scheduler()
56{
57 // Clear out everything that belongs to us to make sure nobody tries to
58 // clear themselves out after the scheduler goes away.
59 clear();
60}
61
62void
63Scheduler::clear()
64{
65 // Delta notifications.
66 while (!deltas.empty())
67 deltas.front()->deschedule();
68
69 // Timed notifications.
70 for (auto &tsp: timeSlots) {
71 TimeSlot *&ts = tsp.second;
72 while (!ts->events.empty())
73 ts->events.front()->deschedule();
74 deschedule(ts);
75 }
76 timeSlots.clear();
77
78 // gem5 events.
79 if (readyEvent.scheduled())
80 deschedule(&readyEvent);
81 if (pauseEvent.scheduled())
82 deschedule(&pauseEvent);
83 if (stopEvent.scheduled())
84 deschedule(&stopEvent);
85 if (starvationEvent.scheduled())
86 deschedule(&starvationEvent);
87 if (maxTickEvent.scheduled())
88 deschedule(&maxTickEvent);
89
90 Process *p;
91 while ((p = toFinalize.getNext()))
92 p->popListNode();
93 while ((p = initList.getNext()))
94 p->popListNode();
95 while ((p = readyListMethods.getNext()))
96 p->popListNode();
97 while ((p = readyListThreads.getNext()))
98 p->popListNode();
99
100 Channel *c;
101 while ((c = updateList.getNext()))
102 c->popListNode();
103}
104
105void
106Scheduler::initPhase()
107{
108 for (Process *p = toFinalize.getNext(); p; p = toFinalize.getNext()) {
109 p->finalize();
110 p->popListNode();
111
112 if (!p->hasStaticSensitivities() && !p->internal()) {
113 SC_REPORT_WARNING(
114 "(W558) disable() or dont_initialize() called on process "
115 "with no static sensitivity, it will be orphaned",
116 p->name());
117 }
118 }
119
120 for (Process *p = initList.getNext(); p; p = initList.getNext()) {
121 p->finalize();
122 p->popListNode();
123 p->ready();
124 }
125
126 update();
127
128 while (!deltas.empty())
129 deltas.front()->run();
130
131 for (auto ets: eventsToSchedule)
132 eq->schedule(ets.first, ets.second);
133 eventsToSchedule.clear();
134
135 if (_started) {
136 if (!runToTime && starved())
137 scheduleStarvationEvent();
138 kernel->status(::sc_core::SC_RUNNING);
139 }
140
141 initDone = true;
142}
143
144void
145Scheduler::reg(Process *p)
146{
147 if (initDone) {
148 // If we're past initialization, finalize static sensitivity.
149 p->finalize();
150 // Mark the process as ready.
151 p->ready();
152 } else {
153 // Otherwise, record that this process should be initialized once we
154 // get there.
155 initList.pushLast(p);
156 }
157}
158
159void
160Scheduler::dontInitialize(Process *p)
161{
162 if (initDone) {
163 // Pop this process off of the ready list.
164 p->popListNode();
165 } else {
166 // Push this process onto the list of processes which still need
167 // their static sensitivity to be finalized. That implicitly pops it
168 // off the list of processes to be initialized/marked ready.
169 toFinalize.pushLast(p);
170 }
171}
172
173void
174Scheduler::yield()
175{
176 // Pull a process from the active list.
177 _current = readyList->getNext();
178 if (!_current) {
179 // There are no more processes, so return control to evaluate.
180 Fiber::primaryFiber()->run();
181 } else {
182 _current->popListNode();
183 // Switch to whatever Fiber is supposed to run this process. All
184 // Fibers which aren't running should be parked at this line.
185 _current->fiber()->run();
186 // If the current process needs to be manually started, start it.
187 if (_current && _current->needsStart()) {
188 _current->needsStart(false);
187 _current->run();
189 try {
190 _current->run();
191 } catch (...) {
192 throwToScMain();
193 }
194 }
195 }
196 if (_current && _current->excWrapper) {
197 // Make sure this isn't a method process.
198 assert(!_current->needsStart());
199 auto ew = _current->excWrapper;
200 _current->excWrapper = nullptr;
201 ew->throw_it();
202 }
203}
204
205void
206Scheduler::ready(Process *p)
207{
208 if (_stopNow)
209 return;
210
211 if (p->procKind() == ::sc_core::SC_METHOD_PROC_)
212 readyListMethods.pushLast(p);
213 else
214 readyListThreads.pushLast(p);
215
216 scheduleReadyEvent();
217}
218
219void
220Scheduler::resume(Process *p)
221{
222 if (initDone)
223 ready(p);
224 else
225 initList.pushLast(p);
226}
227
228bool
229listContains(ListNode *list, ListNode *target)
230{
231 ListNode *n = list->nextListNode;
232 while (n != list)
233 if (n == target)
234 return true;
235 return false;
236}
237
238bool
239Scheduler::suspend(Process *p)
240{
241 bool was_ready;
242 if (initDone) {
243 // After initialization, the only list we can be on is the ready list.
244 was_ready = (p->nextListNode != nullptr);
245 p->popListNode();
246 } else {
247 // Check the ready lists to see if we find this process.
248 was_ready = listContains(&readyListMethods, p) ||
249 listContains(&readyListThreads, p);
250 if (was_ready)
251 toFinalize.pushLast(p);
252 }
253 return was_ready;
254}
255
256void
257Scheduler::requestUpdate(Channel *c)
258{
259 updateList.pushLast(c);
260 scheduleReadyEvent();
261}
262
263void
264Scheduler::scheduleReadyEvent()
265{
266 // Schedule the evaluate and update phases.
267 if (!readyEvent.scheduled()) {
268 schedule(&readyEvent);
269 if (starvationEvent.scheduled())
270 deschedule(&starvationEvent);
271 }
272}
273
274void
275Scheduler::scheduleStarvationEvent()
276{
277 if (!starvationEvent.scheduled()) {
278 schedule(&starvationEvent);
279 if (readyEvent.scheduled())
280 deschedule(&readyEvent);
281 }
282}
283
284void
285Scheduler::runReady()
286{
287 bool empty = readyListMethods.empty() && readyListThreads.empty();
288 lastReadyTick = getCurTick();
289
290 // The evaluation phase.
291 do {
292 // We run methods and threads in two seperate passes to emulate how
293 // Accellera orders things, but without having to scan through a
294 // unified list to find the next process of the correct type.
295 readyList = &readyListMethods;
296 while (!readyListMethods.empty())
297 yield();
298
299 readyList = &readyListThreads;
300 while (!readyListThreads.empty())
301 yield();
302
303 // We already know that readyListThreads is empty at this point.
304 } while (!readyListMethods.empty());
305
306 if (!empty) {
307 _numCycles++;
308 _changeStamp++;
309 }
310
311 if (_stopNow)
312 return;
313
314 // The update phase.
315 update();
316
317 // The delta phase.
318 while (!deltas.empty())
319 deltas.front()->run();
320
321 if (!runToTime && starved())
322 scheduleStarvationEvent();
323
324 if (runOnce)
325 schedulePause();
326}
327
328void
329Scheduler::update()
330{
331 Channel *channel = updateList.getNext();
332 while (channel) {
333 channel->popListNode();
334 channel->update();
335 channel = updateList.getNext();
336 }
337}
338
339void
340Scheduler::pause()
341{
342 _paused = true;
343 kernel->status(::sc_core::SC_PAUSED);
344 runOnce = false;
339 scMain->run();
345 if (scMain && !scMain->finished())
346 scMain->run();
347}
348
349void
350Scheduler::stop()
351{
352 _stopped = true;
353 kernel->stop();
354
355 clear();
356
357 runOnce = false;
351 scMain->run();
358 if (scMain && !scMain->finished())
359 scMain->run();
360}
361
362void
363Scheduler::start(Tick max_tick, bool run_to_time)
364{
365 // We should be running from sc_main. Keep track of that Fiber to return
366 // to later.
367 scMain = Fiber::currentFiber();
368
369 _started = true;
370 _paused = false;
371 _stopped = false;
372 runToTime = run_to_time;
373
374 maxTick = max_tick;
375 lastReadyTick = getCurTick();
376
377 if (initDone) {
378 if (!runToTime && starved())
379 scheduleStarvationEvent();
380 kernel->status(::sc_core::SC_RUNNING);
381 }
382
383 schedule(&maxTickEvent, maxTick);
384
385 // Return to gem5 to let it run events, etc.
386 Fiber::primaryFiber()->run();
387
388 if (pauseEvent.scheduled())
389 deschedule(&pauseEvent);
390 if (stopEvent.scheduled())
391 deschedule(&stopEvent);
392 if (maxTickEvent.scheduled())
393 deschedule(&maxTickEvent);
394 if (starvationEvent.scheduled())
395 deschedule(&starvationEvent);
396
397 if (_throwToScMain) {
398 const ::sc_core::sc_report *to_throw = _throwToScMain;
399 _throwToScMain = nullptr;
400 throw *to_throw;
401 }
402}
403
404void
405Scheduler::oneCycle()
406{
407 runOnce = true;
408 scheduleReadyEvent();
409 start(::MaxTick, false);
410}
411
412void
413Scheduler::schedulePause()
414{
415 if (pauseEvent.scheduled())
416 return;
417
418 schedule(&pauseEvent);
419}
420
421void
422Scheduler::throwToScMain(const ::sc_core::sc_report *r)
423{
424 if (!r)
425 r = reportifyException();
426 _throwToScMain = r;
427 scMain->run();
428}
429
430void
431Scheduler::scheduleStop(bool finish_delta)
432{
433 if (stopEvent.scheduled())
434 return;
435
436 if (!finish_delta) {
437 _stopNow = true;
438 // If we're not supposed to finish the delta cycle, flush all
439 // pending activity.
440 clear();
441 }
442 schedule(&stopEvent);
443}
444
445Scheduler scheduler;
446
447namespace {
448
449void
450throwingReportHandler(const ::sc_core::sc_report &r,
451 const ::sc_core::sc_actions &)
452{
453 throw r;
454}
455
456} // anonymous namespace
457
458const ::sc_core::sc_report *
459reportifyException()
460{
461 ::sc_core::sc_report_handler_proc old_handler =
462 ::sc_core::sc_report_handler::get_handler();
463 ::sc_core::sc_report_handler::set_handler(&throwingReportHandler);
464
465 try {
466 try {
467 // Rethrow the current exception so we can catch it and throw an
468 // sc_report instead if it's not a type we recognize/can handle.
469 throw;
470 } catch (const ::sc_core::sc_report &) {
471 // It's already a sc_report, so nothing to do.
472 throw;
473 } catch (const ::sc_core::sc_unwind_exception &) {
474 panic("Kill/reset exception escaped a Process::run()");
475 } catch (const std::exception &e) {
476 SC_REPORT_ERROR("uncaught exception", e.what());
477 } catch (const char *msg) {
478 SC_REPORT_ERROR("uncaught exception", msg);
479 } catch (...) {
480 SC_REPORT_ERROR("uncaught exception", "UNKNOWN EXCEPTION");
481 }
482 } catch (const ::sc_core::sc_report &r) {
483 ::sc_core::sc_report_handler::set_handler(old_handler);
484 return &r;
485 }
486 panic("No exception thrown in reportifyException.");
487}
488
489} // namespace sc_gem5