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#ifndef __SYSTEMC_CORE_SCHEDULER_HH__
31#define __SYSTEMC_CORE_SCHEDULER_HH__
32
33#include <functional>
34#include <map>
35#include <set>
36#include <vector>
37
38#include "base/logging.hh"
39#include "sim/core.hh"
40#include "sim/eventq.hh"
41#include "systemc/core/channel.hh"
42#include "systemc/core/list.hh"
43#include "systemc/core/process.hh"
44#include "systemc/core/sched_event.hh"
45
46class Fiber;
47
48namespace sc_gem5
49{
50
51class TraceFile;
52
53typedef NodeList<Process> ProcessList;
54typedef NodeList<Channel> ChannelList;
55
56/*
57 * The scheduler supports three different mechanisms, the initialization phase,
58 * delta cycles, and timed notifications.
59 *
60 * INITIALIZATION PHASE
61 *
62 * The initialization phase has three parts:
63 * 1. Run requested channel updates.
64 * 2. Make processes which need to initialize runnable (methods and threads
65 * which didn't have dont_initialize called on them).
66 * 3. Process delta notifications.
67 *
68 * First, the Kernel SimObject calls the update() method during its startup()
69 * callback which handles the requested channel updates. The Kernel also
70 * schedules an event to be run at time 0 with a slightly elevated priority
71 * so that it happens before any "normal" event.
72 *
73 * When that t0 event happens, it calls the schedulers prepareForInit method
74 * which performs step 2 above. That indirectly causes the scheduler's
75 * readyEvent to be scheduled with slightly lowered priority, ensuring it
76 * happens after any "normal" event.
77 *
78 * Because delta notifications are scheduled at the standard priority, all
79 * of those events will happen next, performing step 3 above. Once they finish,
80 * if the readyEvent was scheduled above, there shouldn't be any higher
81 * priority events in front of it. When it runs, it will start the first
82 * evaluate phase of the first delta cycle.
83 *
84 * DELTA CYCLE
85 *
86 * A delta cycle has three phases within it.
87 * 1. The evaluate phase where runnable processes are allowed to run.
88 * 2. The update phase where requested channel updates hapen.
89 * 3. The delta notification phase where delta notifications happen.
90 *
91 * The readyEvent runs all three steps of the delta cycle. It first goes
92 * through the list of runnable processes and executes them until the set is
93 * empty, and then immediately runs the update phase. Since these are all part
94 * of the same event, there's no chance for other events to intervene and
95 * break the required order above.
96 *
97 * During the update phase above, the spec forbids any action which would make
98 * a process runnable. That means that once the update phase finishes, the set
99 * of runnable processes will be empty. There may, however, have been some
100 * delta notifications/timeouts which will have been scheduled during either
101 * the evaluate or update phase above. Those will have been accumulated in the
102 * scheduler, and are now all executed.
103 *
104 * If any processes became runnable during the delta notification phase, the
105 * readyEvent will have been scheduled and will be waiting and ready to run
106 * again, effectively starting the next delta cycle.
107 *
108 * TIMED NOTIFICATION PHASE
109 *
110 * If no processes became runnable, the event queue will continue to process
111 * events until it comes across an event which represents all the timed
112 * notifications which are supposed to happen at a particular time. The object
113 * which tracks them will execute all those notifications, and then destroy
114 * itself. If the readyEvent is now ready to run, the next delta cycle will
115 * start.
116 *
117 * PAUSE/STOP
118 *
119 * To inject a pause from sc_pause which should happen after the current delta
120 * cycle's delta notification phase, an event is scheduled with a lower than
121 * normal priority, but higher than the readyEvent. That ensures that any
122 * delta notifications which are scheduled with normal priority will happen
123 * first, since those are part of the current delta cycle. Then the pause
124 * event will happen before the next readyEvent which would start the next
125 * delta cycle. All of these events are scheduled for the current time, and so
126 * would happen before any timed notifications went off.
127 *
128 * To inject a stop from sc_stop, the delta cycles should stop before even the
129 * delta notifications have happened, but after the evaluate and update phases.
130 * For that, a stop event with slightly higher than normal priority will be
131 * scheduled so that it happens before any of the delta notification events
132 * which are at normal priority.
133 *
134 * MAX RUN TIME
135 *
136 * When sc_start is called, it's possible to pass in a maximum time the
137 * simulation should run to, at which point sc_pause is implicitly called. The
138 * simulation is supposed to run up to the latest timed notification phase
139 * which is less than or equal to the maximum time. In other words it should
140 * run timed notifications at the maximum time, but not the subsequent evaluate
141 * phase. That's implemented by scheduling an event at the max time with a
142 * priority which is lower than all the others except the ready event. Timed
143 * notifications will happen before it fires, but it will override any ready
144 * event and prevent the evaluate phase from starting.
145 */
146
147class Scheduler
148{
149 public:
150 typedef std::list<ScEvent *> ScEvents;
151
152 class TimeSlot : public ::Event
153 {
154 public:
155 TimeSlot() : ::Event(Default_Pri, AutoDelete) {}
156
157 ScEvents events;
158 void process();
159 };
160
161 typedef std::map<Tick, TimeSlot *> TimeSlots;
162
163 Scheduler();
164 ~Scheduler();
165
166 void clear();
167
168 const std::string name() const { return "systemc_scheduler"; }
169
170 uint64_t numCycles() { return _numCycles; }
171 Process *current() { return _current; }
172
173 void initPhase();
174
175 // Register a process with the scheduler.
176 void reg(Process *p);
177
178 // Run the next process, if there is one.
179 void yield();
180
181 // Put a process on the ready list.
182 void ready(Process *p);
183
184 // Mark a process as ready if init is finished, or put it on the list of
185 // processes to be initialized.
186 void resume(Process *p);
187
188 // Remove a process from the ready/init list if it was on one of them, and
189 // return if it was.
190 bool suspend(Process *p);
191
192 // Schedule an update for a given channel.
193 void requestUpdate(Channel *c);
194
195 // Run the given process immediately, preempting whatever may be running.
196 void
197 runNow(Process *p)
198 {
199 // This function may put a process on the wrong list, ie a thread
200 // the method list. That's fine since that's just a performance
201 // optimization, and the important thing here is how the processes are
202 // ordered.
203
204 // If a process is running, schedule it/us to run again.
205 if (_current)
206 readyListMethods.pushFirst(_current);
207 // Schedule p to run first.
208 readyListMethods.pushFirst(p);
209 yield();
210 }
211
| 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#ifndef __SYSTEMC_CORE_SCHEDULER_HH__
31#define __SYSTEMC_CORE_SCHEDULER_HH__
32
33#include <functional>
34#include <map>
35#include <set>
36#include <vector>
37
38#include "base/logging.hh"
39#include "sim/core.hh"
40#include "sim/eventq.hh"
41#include "systemc/core/channel.hh"
42#include "systemc/core/list.hh"
43#include "systemc/core/process.hh"
44#include "systemc/core/sched_event.hh"
45
46class Fiber;
47
48namespace sc_gem5
49{
50
51class TraceFile;
52
53typedef NodeList<Process> ProcessList;
54typedef NodeList<Channel> ChannelList;
55
56/*
57 * The scheduler supports three different mechanisms, the initialization phase,
58 * delta cycles, and timed notifications.
59 *
60 * INITIALIZATION PHASE
61 *
62 * The initialization phase has three parts:
63 * 1. Run requested channel updates.
64 * 2. Make processes which need to initialize runnable (methods and threads
65 * which didn't have dont_initialize called on them).
66 * 3. Process delta notifications.
67 *
68 * First, the Kernel SimObject calls the update() method during its startup()
69 * callback which handles the requested channel updates. The Kernel also
70 * schedules an event to be run at time 0 with a slightly elevated priority
71 * so that it happens before any "normal" event.
72 *
73 * When that t0 event happens, it calls the schedulers prepareForInit method
74 * which performs step 2 above. That indirectly causes the scheduler's
75 * readyEvent to be scheduled with slightly lowered priority, ensuring it
76 * happens after any "normal" event.
77 *
78 * Because delta notifications are scheduled at the standard priority, all
79 * of those events will happen next, performing step 3 above. Once they finish,
80 * if the readyEvent was scheduled above, there shouldn't be any higher
81 * priority events in front of it. When it runs, it will start the first
82 * evaluate phase of the first delta cycle.
83 *
84 * DELTA CYCLE
85 *
86 * A delta cycle has three phases within it.
87 * 1. The evaluate phase where runnable processes are allowed to run.
88 * 2. The update phase where requested channel updates hapen.
89 * 3. The delta notification phase where delta notifications happen.
90 *
91 * The readyEvent runs all three steps of the delta cycle. It first goes
92 * through the list of runnable processes and executes them until the set is
93 * empty, and then immediately runs the update phase. Since these are all part
94 * of the same event, there's no chance for other events to intervene and
95 * break the required order above.
96 *
97 * During the update phase above, the spec forbids any action which would make
98 * a process runnable. That means that once the update phase finishes, the set
99 * of runnable processes will be empty. There may, however, have been some
100 * delta notifications/timeouts which will have been scheduled during either
101 * the evaluate or update phase above. Those will have been accumulated in the
102 * scheduler, and are now all executed.
103 *
104 * If any processes became runnable during the delta notification phase, the
105 * readyEvent will have been scheduled and will be waiting and ready to run
106 * again, effectively starting the next delta cycle.
107 *
108 * TIMED NOTIFICATION PHASE
109 *
110 * If no processes became runnable, the event queue will continue to process
111 * events until it comes across an event which represents all the timed
112 * notifications which are supposed to happen at a particular time. The object
113 * which tracks them will execute all those notifications, and then destroy
114 * itself. If the readyEvent is now ready to run, the next delta cycle will
115 * start.
116 *
117 * PAUSE/STOP
118 *
119 * To inject a pause from sc_pause which should happen after the current delta
120 * cycle's delta notification phase, an event is scheduled with a lower than
121 * normal priority, but higher than the readyEvent. That ensures that any
122 * delta notifications which are scheduled with normal priority will happen
123 * first, since those are part of the current delta cycle. Then the pause
124 * event will happen before the next readyEvent which would start the next
125 * delta cycle. All of these events are scheduled for the current time, and so
126 * would happen before any timed notifications went off.
127 *
128 * To inject a stop from sc_stop, the delta cycles should stop before even the
129 * delta notifications have happened, but after the evaluate and update phases.
130 * For that, a stop event with slightly higher than normal priority will be
131 * scheduled so that it happens before any of the delta notification events
132 * which are at normal priority.
133 *
134 * MAX RUN TIME
135 *
136 * When sc_start is called, it's possible to pass in a maximum time the
137 * simulation should run to, at which point sc_pause is implicitly called. The
138 * simulation is supposed to run up to the latest timed notification phase
139 * which is less than or equal to the maximum time. In other words it should
140 * run timed notifications at the maximum time, but not the subsequent evaluate
141 * phase. That's implemented by scheduling an event at the max time with a
142 * priority which is lower than all the others except the ready event. Timed
143 * notifications will happen before it fires, but it will override any ready
144 * event and prevent the evaluate phase from starting.
145 */
146
147class Scheduler
148{
149 public:
150 typedef std::list<ScEvent *> ScEvents;
151
152 class TimeSlot : public ::Event
153 {
154 public:
155 TimeSlot() : ::Event(Default_Pri, AutoDelete) {}
156
157 ScEvents events;
158 void process();
159 };
160
161 typedef std::map<Tick, TimeSlot *> TimeSlots;
162
163 Scheduler();
164 ~Scheduler();
165
166 void clear();
167
168 const std::string name() const { return "systemc_scheduler"; }
169
170 uint64_t numCycles() { return _numCycles; }
171 Process *current() { return _current; }
172
173 void initPhase();
174
175 // Register a process with the scheduler.
176 void reg(Process *p);
177
178 // Run the next process, if there is one.
179 void yield();
180
181 // Put a process on the ready list.
182 void ready(Process *p);
183
184 // Mark a process as ready if init is finished, or put it on the list of
185 // processes to be initialized.
186 void resume(Process *p);
187
188 // Remove a process from the ready/init list if it was on one of them, and
189 // return if it was.
190 bool suspend(Process *p);
191
192 // Schedule an update for a given channel.
193 void requestUpdate(Channel *c);
194
195 // Run the given process immediately, preempting whatever may be running.
196 void
197 runNow(Process *p)
198 {
199 // This function may put a process on the wrong list, ie a thread
200 // the method list. That's fine since that's just a performance
201 // optimization, and the important thing here is how the processes are
202 // ordered.
203
204 // If a process is running, schedule it/us to run again.
205 if (_current)
206 readyListMethods.pushFirst(_current);
207 // Schedule p to run first.
208 readyListMethods.pushFirst(p);
209 yield();
210 }
211
|
212 // Set an event queue for scheduling events.
213 void setEventQueue(EventQueue *_eq) { eq = _eq; }
214
215 // Get the current time according to gem5.
216 Tick getCurTick() { return eq ? eq->getCurTick() : 0; }
217
218 Tick
219 delayed(const ::sc_core::sc_time &delay)
220 {
221 return getCurTick() + delay.value();
222 }
223
224 // For scheduling delayed/timed notifications/timeouts.
225 void
226 schedule(ScEvent *event, const ::sc_core::sc_time &delay)
227 {
228 Tick tick = delayed(delay);
229 if (tick < getCurTick())
230 tick = getCurTick();
231
232 // Delta notification/timeout.
233 if (delay.value() == 0) {
234 event->schedule(deltas, tick);
235 if (!inEvaluate() && !inUpdate())
236 scheduleReadyEvent();
237 return;
238 }
239
240 // Timed notification/timeout.
241 TimeSlot *&ts = timeSlots[tick];
242 if (!ts) {
243 ts = new TimeSlot;
244 schedule(ts, tick);
245 }
246 event->schedule(ts->events, tick);
247 }
248
249 // For descheduling delayed/timed notifications/timeouts.
250 void
251 deschedule(ScEvent *event)
252 {
253 ScEvents *on = event->scheduledOn();
254
255 if (on == &deltas) {
256 event->deschedule();
257 return;
258 }
259
260 // Timed notification/timeout.
261 auto tsit = timeSlots.find(event->when());
262 panic_if(tsit == timeSlots.end(),
263 "Descheduling event at time with no events.");
264 TimeSlot *ts = tsit->second;
265 ScEvents &events = ts->events;
266 assert(on == &events);
267 event->deschedule();
268
269 // If no more events are happening at this time slot, get rid of it.
270 if (events.empty()) {
271 deschedule(ts);
272 timeSlots.erase(tsit);
273 }
274 }
275
276 void
277 completeTimeSlot(TimeSlot *ts)
278 {
279 _changeStamp++;
280 assert(ts == timeSlots.begin()->second);
281 timeSlots.erase(timeSlots.begin());
282 if (!runToTime && starved())
283 scheduleStarvationEvent();
284 scheduleTimeAdvancesEvent();
285 }
286
287 // Pending activity ignores gem5 activity, much like how a systemc
288 // simulation wouldn't know about asynchronous external events (socket IO
289 // for instance) that might happen before time advances in a pure
290 // systemc simulation. Also the spec lists what specific types of pending
291 // activity needs to be counted, which obviously doesn't include gem5
292 // events.
293
294 // Return whether there's pending systemc activity at this time.
295 bool
296 pendingCurr()
297 {
298 return !readyListMethods.empty() || !readyListThreads.empty() ||
299 !updateList.empty() || !deltas.empty();
300 }
301
302 // Return whether there are pending timed notifications or timeouts.
303 bool
304 pendingFuture()
305 {
306 return !timeSlots.empty();
307 }
308
309 // Return how many ticks there are until the first pending event, if any.
310 Tick
311 timeToPending()
312 {
313 if (pendingCurr())
314 return 0;
315 if (pendingFuture())
316 return timeSlots.begin()->first - getCurTick();
317 return MaxTick - getCurTick();
318 }
319
320 // Run scheduled channel updates.
321 void runUpdate();
322
323 // Run delta events.
324 void runDelta();
325
326 void setScMainFiber(Fiber *sc_main) { scMain = sc_main; }
327
328 void start(Tick max_tick, bool run_to_time);
329 void oneCycle();
330
331 void schedulePause();
332 void scheduleStop(bool finish_delta);
333
334 enum Status
335 {
336 StatusOther = 0,
337 StatusEvaluate,
338 StatusUpdate,
339 StatusDelta,
340 StatusTiming,
341 StatusPaused,
342 StatusStopped
343 };
344
345 bool elaborationDone() { return _elaborationDone; }
346 void elaborationDone(bool b) { _elaborationDone = b; }
347
348 bool paused() { return status() == StatusPaused; }
349 bool stopped() { return status() == StatusStopped; }
350 bool inEvaluate() { return status() == StatusEvaluate; }
351 bool inUpdate() { return status() == StatusUpdate; }
352 bool inDelta() { return status() == StatusDelta; }
353 bool inTiming() { return status() == StatusTiming; }
354
355 uint64_t changeStamp() { return _changeStamp; }
356
357 void throwToScMain(const ::sc_core::sc_report *r=nullptr);
358
359 Status status() { return _status; }
360 void status(Status s) { _status = s; }
361
362 void registerTraceFile(TraceFile *tf) { traceFiles.insert(tf); }
363 void unregisterTraceFile(TraceFile *tf) { traceFiles.erase(tf); }
364
365 private:
366 typedef const EventBase::Priority Priority;
367 static Priority DefaultPriority = EventBase::Default_Pri;
368
369 static Priority StopPriority = DefaultPriority - 1;
370 static Priority PausePriority = DefaultPriority + 1;
371 static Priority MaxTickPriority = DefaultPriority + 2;
372 static Priority ReadyPriority = DefaultPriority + 3;
373 static Priority StarvationPriority = ReadyPriority;
374 static Priority TimeAdvancesPriority = EventBase::Maximum_Pri;
375
376 EventQueue *eq;
377
378 // For gem5 style events.
379 void
380 schedule(::Event *event, Tick tick)
381 {
382 if (initDone)
383 eq->schedule(event, tick);
384 else
385 eventsToSchedule[event] = tick;
386 }
387
388 void schedule(::Event *event) { schedule(event, getCurTick()); }
389
390 void
391 deschedule(::Event *event)
392 {
393 if (initDone)
394 eq->deschedule(event);
395 else
396 eventsToSchedule.erase(event);
397 }
398
399 ScEvents deltas;
400 TimeSlots timeSlots;
401
402 Process *
403 getNextReady()
404 {
405 Process *p = readyListMethods.getNext();
406 return p ? p : readyListThreads.getNext();
407 }
408
409 void runReady();
410 EventWrapper<Scheduler, &Scheduler::runReady> readyEvent;
411 void scheduleReadyEvent();
412
413 void pause();
414 void stop();
415 EventWrapper<Scheduler, &Scheduler::pause> pauseEvent;
416 EventWrapper<Scheduler, &Scheduler::stop> stopEvent;
417
418 Fiber *scMain;
419 const ::sc_core::sc_report *_throwToScMain;
420
421 bool
422 starved()
423 {
424 return (readyListMethods.empty() && readyListThreads.empty() &&
425 updateList.empty() && deltas.empty() &&
426 (timeSlots.empty() || timeSlots.begin()->first > maxTick) &&
427 initList.empty());
428 }
429 EventWrapper<Scheduler, &Scheduler::pause> starvationEvent;
430 void scheduleStarvationEvent();
431
432 bool _elaborationDone;
433 bool _started;
434 bool _stopNow;
435
436 Status _status;
437
438 Tick maxTick;
439 Tick lastReadyTick;
440 void
441 maxTickFunc()
442 {
443 if (lastReadyTick != getCurTick())
444 _changeStamp++;
445 pause();
446 }
447 EventWrapper<Scheduler, &Scheduler::maxTickFunc> maxTickEvent;
448
449 void timeAdvances() { trace(false); }
450 EventWrapper<Scheduler, &Scheduler::timeAdvances> timeAdvancesEvent;
451 void
452 scheduleTimeAdvancesEvent()
453 {
454 if (!traceFiles.empty() && !timeAdvancesEvent.scheduled())
455 schedule(&timeAdvancesEvent);
456 }
457
458 uint64_t _numCycles;
459 uint64_t _changeStamp;
460
461 Process *_current;
462
463 bool initDone;
464 bool runToTime;
465 bool runOnce;
466
467 ProcessList initList;
468
469 ProcessList readyListMethods;
470 ProcessList readyListThreads;
471
472 ChannelList updateList;
473
474 std::map<::Event *, Tick> eventsToSchedule;
475
476 std::set<TraceFile *> traceFiles;
477
478 void trace(bool delta);
479};
480
481extern Scheduler scheduler;
482
483inline void
484Scheduler::TimeSlot::process()
485{
486 scheduler.status(StatusTiming);
487
488 try {
489 while (!events.empty())
490 events.front()->run();
491 } catch (...) {
492 if (events.empty())
493 scheduler.completeTimeSlot(this);
494 else
495 scheduler.schedule(this);
496 scheduler.throwToScMain();
497 }
498
499 scheduler.status(StatusOther);
500 scheduler.completeTimeSlot(this);
501}
502
503const ::sc_core::sc_report *reportifyException();
504
505} // namespace sc_gem5
506
507#endif // __SYSTEMC_CORE_SCHEDULER_H__
| 223 // Set an event queue for scheduling events.
224 void setEventQueue(EventQueue *_eq) { eq = _eq; }
225
226 // Get the current time according to gem5.
227 Tick getCurTick() { return eq ? eq->getCurTick() : 0; }
228
229 Tick
230 delayed(const ::sc_core::sc_time &delay)
231 {
232 return getCurTick() + delay.value();
233 }
234
235 // For scheduling delayed/timed notifications/timeouts.
236 void
237 schedule(ScEvent *event, const ::sc_core::sc_time &delay)
238 {
239 Tick tick = delayed(delay);
240 if (tick < getCurTick())
241 tick = getCurTick();
242
243 // Delta notification/timeout.
244 if (delay.value() == 0) {
245 event->schedule(deltas, tick);
246 if (!inEvaluate() && !inUpdate())
247 scheduleReadyEvent();
248 return;
249 }
250
251 // Timed notification/timeout.
252 TimeSlot *&ts = timeSlots[tick];
253 if (!ts) {
254 ts = new TimeSlot;
255 schedule(ts, tick);
256 }
257 event->schedule(ts->events, tick);
258 }
259
260 // For descheduling delayed/timed notifications/timeouts.
261 void
262 deschedule(ScEvent *event)
263 {
264 ScEvents *on = event->scheduledOn();
265
266 if (on == &deltas) {
267 event->deschedule();
268 return;
269 }
270
271 // Timed notification/timeout.
272 auto tsit = timeSlots.find(event->when());
273 panic_if(tsit == timeSlots.end(),
274 "Descheduling event at time with no events.");
275 TimeSlot *ts = tsit->second;
276 ScEvents &events = ts->events;
277 assert(on == &events);
278 event->deschedule();
279
280 // If no more events are happening at this time slot, get rid of it.
281 if (events.empty()) {
282 deschedule(ts);
283 timeSlots.erase(tsit);
284 }
285 }
286
287 void
288 completeTimeSlot(TimeSlot *ts)
289 {
290 _changeStamp++;
291 assert(ts == timeSlots.begin()->second);
292 timeSlots.erase(timeSlots.begin());
293 if (!runToTime && starved())
294 scheduleStarvationEvent();
295 scheduleTimeAdvancesEvent();
296 }
297
298 // Pending activity ignores gem5 activity, much like how a systemc
299 // simulation wouldn't know about asynchronous external events (socket IO
300 // for instance) that might happen before time advances in a pure
301 // systemc simulation. Also the spec lists what specific types of pending
302 // activity needs to be counted, which obviously doesn't include gem5
303 // events.
304
305 // Return whether there's pending systemc activity at this time.
306 bool
307 pendingCurr()
308 {
309 return !readyListMethods.empty() || !readyListThreads.empty() ||
310 !updateList.empty() || !deltas.empty();
311 }
312
313 // Return whether there are pending timed notifications or timeouts.
314 bool
315 pendingFuture()
316 {
317 return !timeSlots.empty();
318 }
319
320 // Return how many ticks there are until the first pending event, if any.
321 Tick
322 timeToPending()
323 {
324 if (pendingCurr())
325 return 0;
326 if (pendingFuture())
327 return timeSlots.begin()->first - getCurTick();
328 return MaxTick - getCurTick();
329 }
330
331 // Run scheduled channel updates.
332 void runUpdate();
333
334 // Run delta events.
335 void runDelta();
336
337 void setScMainFiber(Fiber *sc_main) { scMain = sc_main; }
338
339 void start(Tick max_tick, bool run_to_time);
340 void oneCycle();
341
342 void schedulePause();
343 void scheduleStop(bool finish_delta);
344
345 enum Status
346 {
347 StatusOther = 0,
348 StatusEvaluate,
349 StatusUpdate,
350 StatusDelta,
351 StatusTiming,
352 StatusPaused,
353 StatusStopped
354 };
355
356 bool elaborationDone() { return _elaborationDone; }
357 void elaborationDone(bool b) { _elaborationDone = b; }
358
359 bool paused() { return status() == StatusPaused; }
360 bool stopped() { return status() == StatusStopped; }
361 bool inEvaluate() { return status() == StatusEvaluate; }
362 bool inUpdate() { return status() == StatusUpdate; }
363 bool inDelta() { return status() == StatusDelta; }
364 bool inTiming() { return status() == StatusTiming; }
365
366 uint64_t changeStamp() { return _changeStamp; }
367
368 void throwToScMain(const ::sc_core::sc_report *r=nullptr);
369
370 Status status() { return _status; }
371 void status(Status s) { _status = s; }
372
373 void registerTraceFile(TraceFile *tf) { traceFiles.insert(tf); }
374 void unregisterTraceFile(TraceFile *tf) { traceFiles.erase(tf); }
375
376 private:
377 typedef const EventBase::Priority Priority;
378 static Priority DefaultPriority = EventBase::Default_Pri;
379
380 static Priority StopPriority = DefaultPriority - 1;
381 static Priority PausePriority = DefaultPriority + 1;
382 static Priority MaxTickPriority = DefaultPriority + 2;
383 static Priority ReadyPriority = DefaultPriority + 3;
384 static Priority StarvationPriority = ReadyPriority;
385 static Priority TimeAdvancesPriority = EventBase::Maximum_Pri;
386
387 EventQueue *eq;
388
389 // For gem5 style events.
390 void
391 schedule(::Event *event, Tick tick)
392 {
393 if (initDone)
394 eq->schedule(event, tick);
395 else
396 eventsToSchedule[event] = tick;
397 }
398
399 void schedule(::Event *event) { schedule(event, getCurTick()); }
400
401 void
402 deschedule(::Event *event)
403 {
404 if (initDone)
405 eq->deschedule(event);
406 else
407 eventsToSchedule.erase(event);
408 }
409
410 ScEvents deltas;
411 TimeSlots timeSlots;
412
413 Process *
414 getNextReady()
415 {
416 Process *p = readyListMethods.getNext();
417 return p ? p : readyListThreads.getNext();
418 }
419
420 void runReady();
421 EventWrapper<Scheduler, &Scheduler::runReady> readyEvent;
422 void scheduleReadyEvent();
423
424 void pause();
425 void stop();
426 EventWrapper<Scheduler, &Scheduler::pause> pauseEvent;
427 EventWrapper<Scheduler, &Scheduler::stop> stopEvent;
428
429 Fiber *scMain;
430 const ::sc_core::sc_report *_throwToScMain;
431
432 bool
433 starved()
434 {
435 return (readyListMethods.empty() && readyListThreads.empty() &&
436 updateList.empty() && deltas.empty() &&
437 (timeSlots.empty() || timeSlots.begin()->first > maxTick) &&
438 initList.empty());
439 }
440 EventWrapper<Scheduler, &Scheduler::pause> starvationEvent;
441 void scheduleStarvationEvent();
442
443 bool _elaborationDone;
444 bool _started;
445 bool _stopNow;
446
447 Status _status;
448
449 Tick maxTick;
450 Tick lastReadyTick;
451 void
452 maxTickFunc()
453 {
454 if (lastReadyTick != getCurTick())
455 _changeStamp++;
456 pause();
457 }
458 EventWrapper<Scheduler, &Scheduler::maxTickFunc> maxTickEvent;
459
460 void timeAdvances() { trace(false); }
461 EventWrapper<Scheduler, &Scheduler::timeAdvances> timeAdvancesEvent;
462 void
463 scheduleTimeAdvancesEvent()
464 {
465 if (!traceFiles.empty() && !timeAdvancesEvent.scheduled())
466 schedule(&timeAdvancesEvent);
467 }
468
469 uint64_t _numCycles;
470 uint64_t _changeStamp;
471
472 Process *_current;
473
474 bool initDone;
475 bool runToTime;
476 bool runOnce;
477
478 ProcessList initList;
479
480 ProcessList readyListMethods;
481 ProcessList readyListThreads;
482
483 ChannelList updateList;
484
485 std::map<::Event *, Tick> eventsToSchedule;
486
487 std::set<TraceFile *> traceFiles;
488
489 void trace(bool delta);
490};
491
492extern Scheduler scheduler;
493
494inline void
495Scheduler::TimeSlot::process()
496{
497 scheduler.status(StatusTiming);
498
499 try {
500 while (!events.empty())
501 events.front()->run();
502 } catch (...) {
503 if (events.empty())
504 scheduler.completeTimeSlot(this);
505 else
506 scheduler.schedule(this);
507 scheduler.throwToScMain();
508 }
509
510 scheduler.status(StatusOther);
511 scheduler.completeTimeSlot(this);
512}
513
514const ::sc_core::sc_report *reportifyException();
515
516} // namespace sc_gem5
517
518#endif // __SYSTEMC_CORE_SCHEDULER_H__
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