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
51typedef NodeList<Process> ProcessList;
52typedef NodeList<Channel> ChannelList;
53
54/*
55 * The scheduler supports three different mechanisms, the initialization phase,
56 * delta cycles, and timed notifications.
57 *
58 * INITIALIZATION PHASE
59 *
60 * The initialization phase has three parts:
61 * 1. Run requested channel updates.
62 * 2. Make processes which need to initialize runnable (methods and threads
63 * which didn't have dont_initialize called on them).
64 * 3. Process delta notifications.
65 *
66 * First, the Kernel SimObject calls the update() method during its startup()
67 * callback which handles the requested channel updates. The Kernel also
68 * schedules an event to be run at time 0 with a slightly elevated priority
69 * so that it happens before any "normal" event.
70 *
71 * When that t0 event happens, it calls the schedulers prepareForInit method
72 * which performs step 2 above. That indirectly causes the scheduler's
73 * readyEvent to be scheduled with slightly lowered priority, ensuring it
74 * happens after any "normal" event.
75 *
76 * Because delta notifications are scheduled at the standard priority, all
77 * of those events will happen next, performing step 3 above. Once they finish,
78 * if the readyEvent was scheduled above, there shouldn't be any higher
79 * priority events in front of it. When it runs, it will start the first
80 * evaluate phase of the first delta cycle.
81 *
82 * DELTA CYCLE
83 *
84 * A delta cycle has three phases within it.
85 * 1. The evaluate phase where runnable processes are allowed to run.
86 * 2. The update phase where requested channel updates hapen.
87 * 3. The delta notification phase where delta notifications happen.
88 *
89 * The readyEvent runs all three steps of the delta cycle. It first goes
90 * through the list of runnable processes and executes them until the set is
91 * empty, and then immediately runs the update phase. Since these are all part
92 * of the same event, there's no chance for other events to intervene and
93 * break the required order above.
94 *
95 * During the update phase above, the spec forbids any action which would make
96 * a process runnable. That means that once the update phase finishes, the set
97 * of runnable processes will be empty. There may, however, have been some
98 * delta notifications/timeouts which will have been scheduled during either
99 * the evaluate or update phase above. Those will have been accumulated in the
100 * scheduler, and are now all executed.
101 *
102 * If any processes became runnable during the delta notification phase, the
103 * readyEvent will have been scheduled and will be waiting and ready to run
104 * again, effectively starting the next delta cycle.
105 *
106 * TIMED NOTIFICATION PHASE
107 *
108 * If no processes became runnable, the event queue will continue to process
109 * events until it comes across an event which represents all the timed
110 * notifications which are supposed to happen at a particular time. The object
111 * which tracks them will execute all those notifications, and then destroy
112 * itself. If the readyEvent is now ready to run, the next delta cycle will
113 * start.
114 *
115 * PAUSE/STOP
116 *
117 * To inject a pause from sc_pause which should happen after the current delta
118 * cycle's delta notification phase, an event is scheduled with a lower than
119 * normal priority, but higher than the readyEvent. That ensures that any
120 * delta notifications which are scheduled with normal priority will happen
121 * first, since those are part of the current delta cycle. Then the pause
122 * event will happen before the next readyEvent which would start the next
123 * delta cycle. All of these events are scheduled for the current time, and so
124 * would happen before any timed notifications went off.
125 *
126 * To inject a stop from sc_stop, the delta cycles should stop before even the
127 * delta notifications have happened, but after the evaluate and update phases.
128 * For that, a stop event with slightly higher than normal priority will be
129 * scheduled so that it happens before any of the delta notification events
130 * which are at normal priority.
131 *
132 * MAX RUN TIME
133 *
134 * When sc_start is called, it's possible to pass in a maximum time the
135 * simulation should run to, at which point sc_pause is implicitly called. The
136 * simulation is supposed to run up to the latest timed notification phase
137 * which is less than or equal to the maximum time. In other words it should
138 * run timed notifications at the maximum time, but not the subsequent evaluate
139 * phase. That's implemented by scheduling an event at the max time with a
140 * priority which is lower than all the others except the ready event. Timed
141 * notifications will happen before it fires, but it will override any ready
142 * event and prevent the evaluate phase from starting.
143 */
144
145class Scheduler
146{
147 public:
148 typedef std::set<ScEvent *> ScEvents;
149
150 class TimeSlot : public ::Event
151 {
152 public:
153 TimeSlot() : ::Event(Default_Pri, AutoDelete) {}
154
155 ScEvents events;
156 void process();
157 };
158
159 typedef std::map<Tick, TimeSlot *> TimeSlots;
160
161 Scheduler();
162
163 const std::string name() const { return "systemc_scheduler"; }
164
165 uint64_t numCycles() { return _numCycles; }
166 Process *current() { return _current; }
167
| 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
51typedef NodeList<Process> ProcessList;
52typedef NodeList<Channel> ChannelList;
53
54/*
55 * The scheduler supports three different mechanisms, the initialization phase,
56 * delta cycles, and timed notifications.
57 *
58 * INITIALIZATION PHASE
59 *
60 * The initialization phase has three parts:
61 * 1. Run requested channel updates.
62 * 2. Make processes which need to initialize runnable (methods and threads
63 * which didn't have dont_initialize called on them).
64 * 3. Process delta notifications.
65 *
66 * First, the Kernel SimObject calls the update() method during its startup()
67 * callback which handles the requested channel updates. The Kernel also
68 * schedules an event to be run at time 0 with a slightly elevated priority
69 * so that it happens before any "normal" event.
70 *
71 * When that t0 event happens, it calls the schedulers prepareForInit method
72 * which performs step 2 above. That indirectly causes the scheduler's
73 * readyEvent to be scheduled with slightly lowered priority, ensuring it
74 * happens after any "normal" event.
75 *
76 * Because delta notifications are scheduled at the standard priority, all
77 * of those events will happen next, performing step 3 above. Once they finish,
78 * if the readyEvent was scheduled above, there shouldn't be any higher
79 * priority events in front of it. When it runs, it will start the first
80 * evaluate phase of the first delta cycle.
81 *
82 * DELTA CYCLE
83 *
84 * A delta cycle has three phases within it.
85 * 1. The evaluate phase where runnable processes are allowed to run.
86 * 2. The update phase where requested channel updates hapen.
87 * 3. The delta notification phase where delta notifications happen.
88 *
89 * The readyEvent runs all three steps of the delta cycle. It first goes
90 * through the list of runnable processes and executes them until the set is
91 * empty, and then immediately runs the update phase. Since these are all part
92 * of the same event, there's no chance for other events to intervene and
93 * break the required order above.
94 *
95 * During the update phase above, the spec forbids any action which would make
96 * a process runnable. That means that once the update phase finishes, the set
97 * of runnable processes will be empty. There may, however, have been some
98 * delta notifications/timeouts which will have been scheduled during either
99 * the evaluate or update phase above. Those will have been accumulated in the
100 * scheduler, and are now all executed.
101 *
102 * If any processes became runnable during the delta notification phase, the
103 * readyEvent will have been scheduled and will be waiting and ready to run
104 * again, effectively starting the next delta cycle.
105 *
106 * TIMED NOTIFICATION PHASE
107 *
108 * If no processes became runnable, the event queue will continue to process
109 * events until it comes across an event which represents all the timed
110 * notifications which are supposed to happen at a particular time. The object
111 * which tracks them will execute all those notifications, and then destroy
112 * itself. If the readyEvent is now ready to run, the next delta cycle will
113 * start.
114 *
115 * PAUSE/STOP
116 *
117 * To inject a pause from sc_pause which should happen after the current delta
118 * cycle's delta notification phase, an event is scheduled with a lower than
119 * normal priority, but higher than the readyEvent. That ensures that any
120 * delta notifications which are scheduled with normal priority will happen
121 * first, since those are part of the current delta cycle. Then the pause
122 * event will happen before the next readyEvent which would start the next
123 * delta cycle. All of these events are scheduled for the current time, and so
124 * would happen before any timed notifications went off.
125 *
126 * To inject a stop from sc_stop, the delta cycles should stop before even the
127 * delta notifications have happened, but after the evaluate and update phases.
128 * For that, a stop event with slightly higher than normal priority will be
129 * scheduled so that it happens before any of the delta notification events
130 * which are at normal priority.
131 *
132 * MAX RUN TIME
133 *
134 * When sc_start is called, it's possible to pass in a maximum time the
135 * simulation should run to, at which point sc_pause is implicitly called. The
136 * simulation is supposed to run up to the latest timed notification phase
137 * which is less than or equal to the maximum time. In other words it should
138 * run timed notifications at the maximum time, but not the subsequent evaluate
139 * phase. That's implemented by scheduling an event at the max time with a
140 * priority which is lower than all the others except the ready event. Timed
141 * notifications will happen before it fires, but it will override any ready
142 * event and prevent the evaluate phase from starting.
143 */
144
145class Scheduler
146{
147 public:
148 typedef std::set<ScEvent *> ScEvents;
149
150 class TimeSlot : public ::Event
151 {
152 public:
153 TimeSlot() : ::Event(Default_Pri, AutoDelete) {}
154
155 ScEvents events;
156 void process();
157 };
158
159 typedef std::map<Tick, TimeSlot *> TimeSlots;
160
161 Scheduler();
162
163 const std::string name() const { return "systemc_scheduler"; }
164
165 uint64_t numCycles() { return _numCycles; }
166 Process *current() { return _current; }
167
|
260 eq->deschedule(ts);
261 else
262 eventsToSchedule.erase(ts);
263 timeSlots.erase(tsit);
264 }
265 }
266
267 void
268 completeTimeSlot(TimeSlot *ts)
269 {
270 assert(ts == timeSlots.begin()->second);
271 timeSlots.erase(timeSlots.begin());
272 }
273
274 // Pending activity ignores gem5 activity, much like how a systemc
275 // simulation wouldn't know about asynchronous external events (socket IO
276 // for instance) that might happen before time advances in a pure
277 // systemc simulation. Also the spec lists what specific types of pending
278 // activity needs to be counted, which obviously doesn't include gem5
279 // events.
280
281 // Return whether there's pending systemc activity at this time.
282 bool
283 pendingCurr()
284 {
285 return !readyList.empty() || !updateList.empty() || !deltas.empty();
286 }
287
288 // Return whether there are pending timed notifications or timeouts.
289 bool
290 pendingFuture()
291 {
292 return !timeSlots.empty();
293 }
294
295 // Return how many ticks there are until the first pending event, if any.
296 Tick
297 timeToPending()
298 {
299 if (pendingCurr())
300 return 0;
301 if (pendingFuture())
302 return timeSlots.begin()->first - getCurTick();
303 return MaxTick - getCurTick();
304 }
305
306 // Run scheduled channel updates.
307 void update();
308
309 void setScMainFiber(Fiber *sc_main) { scMain = sc_main; }
310
311 void start(Tick max_tick, bool run_to_time);
312 void oneCycle();
313
314 void schedulePause();
315 void scheduleStop(bool finish_delta);
316
317 bool paused() { return _paused; }
318 bool stopped() { return _stopped; }
319
320 private:
321 typedef const EventBase::Priority Priority;
322 static Priority DefaultPriority = EventBase::Default_Pri;
323
324 static Priority StopPriority = DefaultPriority - 1;
325 static Priority PausePriority = DefaultPriority + 1;
326 static Priority MaxTickPriority = DefaultPriority + 2;
327 static Priority ReadyPriority = DefaultPriority + 3;
328 static Priority StarvationPriority = ReadyPriority;
329
330 EventQueue *eq;
331
332 ScEvents deltas;
333 TimeSlots timeSlots;
334
335 void runReady();
336 EventWrapper<Scheduler, &Scheduler::runReady> readyEvent;
337 void scheduleReadyEvent();
338
339 void pause();
340 void stop();
341 EventWrapper<Scheduler, &Scheduler::pause> pauseEvent;
342 EventWrapper<Scheduler, &Scheduler::stop> stopEvent;
343 Fiber *scMain;
344
345 bool
346 starved()
347 {
348 return (readyList.empty() && updateList.empty() && deltas.empty() &&
349 (timeSlots.empty() || timeSlots.begin()->first > maxTick) &&
350 initList.empty());
351 }
352 EventWrapper<Scheduler, &Scheduler::pause> starvationEvent;
353 void scheduleStarvationEvent();
354
355 bool _started;
356 bool _paused;
357 bool _stopped;
358
359 Tick maxTick;
360 EventWrapper<Scheduler, &Scheduler::pause> maxTickEvent;
361
362 uint64_t _numCycles;
363
364 Process *_current;
365
| 259 eq->deschedule(ts);
260 else
261 eventsToSchedule.erase(ts);
262 timeSlots.erase(tsit);
263 }
264 }
265
266 void
267 completeTimeSlot(TimeSlot *ts)
268 {
269 assert(ts == timeSlots.begin()->second);
270 timeSlots.erase(timeSlots.begin());
271 }
272
273 // Pending activity ignores gem5 activity, much like how a systemc
274 // simulation wouldn't know about asynchronous external events (socket IO
275 // for instance) that might happen before time advances in a pure
276 // systemc simulation. Also the spec lists what specific types of pending
277 // activity needs to be counted, which obviously doesn't include gem5
278 // events.
279
280 // Return whether there's pending systemc activity at this time.
281 bool
282 pendingCurr()
283 {
284 return !readyList.empty() || !updateList.empty() || !deltas.empty();
285 }
286
287 // Return whether there are pending timed notifications or timeouts.
288 bool
289 pendingFuture()
290 {
291 return !timeSlots.empty();
292 }
293
294 // Return how many ticks there are until the first pending event, if any.
295 Tick
296 timeToPending()
297 {
298 if (pendingCurr())
299 return 0;
300 if (pendingFuture())
301 return timeSlots.begin()->first - getCurTick();
302 return MaxTick - getCurTick();
303 }
304
305 // Run scheduled channel updates.
306 void update();
307
308 void setScMainFiber(Fiber *sc_main) { scMain = sc_main; }
309
310 void start(Tick max_tick, bool run_to_time);
311 void oneCycle();
312
313 void schedulePause();
314 void scheduleStop(bool finish_delta);
315
316 bool paused() { return _paused; }
317 bool stopped() { return _stopped; }
318
319 private:
320 typedef const EventBase::Priority Priority;
321 static Priority DefaultPriority = EventBase::Default_Pri;
322
323 static Priority StopPriority = DefaultPriority - 1;
324 static Priority PausePriority = DefaultPriority + 1;
325 static Priority MaxTickPriority = DefaultPriority + 2;
326 static Priority ReadyPriority = DefaultPriority + 3;
327 static Priority StarvationPriority = ReadyPriority;
328
329 EventQueue *eq;
330
331 ScEvents deltas;
332 TimeSlots timeSlots;
333
334 void runReady();
335 EventWrapper<Scheduler, &Scheduler::runReady> readyEvent;
336 void scheduleReadyEvent();
337
338 void pause();
339 void stop();
340 EventWrapper<Scheduler, &Scheduler::pause> pauseEvent;
341 EventWrapper<Scheduler, &Scheduler::stop> stopEvent;
342 Fiber *scMain;
343
344 bool
345 starved()
346 {
347 return (readyList.empty() && updateList.empty() && deltas.empty() &&
348 (timeSlots.empty() || timeSlots.begin()->first > maxTick) &&
349 initList.empty());
350 }
351 EventWrapper<Scheduler, &Scheduler::pause> starvationEvent;
352 void scheduleStarvationEvent();
353
354 bool _started;
355 bool _paused;
356 bool _stopped;
357
358 Tick maxTick;
359 EventWrapper<Scheduler, &Scheduler::pause> maxTickEvent;
360
361 uint64_t _numCycles;
362
363 Process *_current;
364
|