1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
|
/*
* Copyright 2018 Google, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Authors: Gabe Black
*/
#include "systemc/core/scheduler.hh"
#include "base/fiber.hh"
#include "base/logging.hh"
#include "sim/eventq.hh"
#include "systemc/core/kernel.hh"
#include "systemc/ext/core/sc_main.hh"
namespace sc_gem5
{
Scheduler::Scheduler() :
eq(nullptr), readyEvent(this, false, ReadyPriority),
pauseEvent(this, false, PausePriority),
stopEvent(this, false, StopPriority),
scMain(nullptr),
starvationEvent(this, false, StarvationPriority),
_started(false), _paused(false), _stopped(false),
maxTickEvent(this, false, MaxTickPriority),
_numCycles(0), _current(nullptr), initDone(false),
runOnce(false)
{}
Scheduler::~Scheduler()
{
// Clear out everything that belongs to us to make sure nobody tries to
// clear themselves out after the scheduler goes away.
clear();
}
void
Scheduler::clear()
{
// Delta notifications.
for (auto &e: deltas)
e->deschedule();
deltas.clear();
// Timed notifications.
for (auto &tsp: timeSlots) {
TimeSlot *&ts = tsp.second;
for (auto &e: ts->events)
e->deschedule();
deschedule(ts);
}
timeSlots.clear();
// gem5 events.
if (readyEvent.scheduled())
deschedule(&readyEvent);
if (pauseEvent.scheduled())
deschedule(&pauseEvent);
if (stopEvent.scheduled())
deschedule(&stopEvent);
if (starvationEvent.scheduled())
deschedule(&starvationEvent);
if (maxTickEvent.scheduled())
deschedule(&maxTickEvent);
Process *p;
while ((p = toFinalize.getNext()))
p->popListNode();
while ((p = initList.getNext()))
p->popListNode();
while ((p = readyList.getNext()))
p->popListNode();
Channel *c;
while ((c = updateList.getNext()))
c->popListNode();
}
void
Scheduler::initPhase()
{
for (Process *p = toFinalize.getNext(); p; p = toFinalize.getNext()) {
p->finalize();
p->popListNode();
}
for (Process *p = initList.getNext(); p; p = initList.getNext()) {
p->finalize();
p->popListNode();
p->ready();
}
update();
for (auto &e: deltas)
e->run();
deltas.clear();
for (auto ets: eventsToSchedule)
eq->schedule(ets.first, ets.second);
eventsToSchedule.clear();
if (_started) {
if (!runToTime && starved())
scheduleStarvationEvent();
kernel->status(::sc_core::SC_RUNNING);
}
initDone = true;
}
void
Scheduler::reg(Process *p)
{
if (initDone) {
// If we're past initialization, finalize static sensitivity.
p->finalize();
// Mark the process as ready.
p->ready();
} else {
// Otherwise, record that this process should be initialized once we
// get there.
initList.pushLast(p);
}
}
void
Scheduler::dontInitialize(Process *p)
{
if (initDone) {
// Pop this process off of the ready list.
p->popListNode();
} else {
// Push this process onto the list of processes which still need
// their static sensitivity to be finalized. That implicitly pops it
// off the list of processes to be initialized/marked ready.
toFinalize.pushLast(p);
}
}
void
Scheduler::yield()
{
_current = readyList.getNext();
if (!_current) {
// There are no more processes, so return control to evaluate.
Fiber::primaryFiber()->run();
} else {
_current->popListNode();
// Switch to whatever Fiber is supposed to run this process. All
// Fibers which aren't running should be parked at this line.
_current->fiber()->run();
// If the current process needs to be manually started, start it.
if (_current && _current->needsStart()) {
_current->needsStart(false);
_current->run();
}
}
if (_current && _current->excWrapper) {
// Make sure this isn't a method process.
assert(!_current->needsStart());
auto ew = _current->excWrapper;
_current->excWrapper = nullptr;
ew->throw_it();
}
}
void
Scheduler::ready(Process *p)
{
// Clump methods together to minimize context switching.
if (p->procKind() == ::sc_core::SC_METHOD_PROC_)
readyList.pushFirst(p);
else
readyList.pushLast(p);
scheduleReadyEvent();
}
void
Scheduler::requestUpdate(Channel *c)
{
updateList.pushLast(c);
scheduleReadyEvent();
}
void
Scheduler::scheduleReadyEvent()
{
// Schedule the evaluate and update phases.
if (!readyEvent.scheduled()) {
schedule(&readyEvent);
if (starvationEvent.scheduled())
deschedule(&starvationEvent);
}
}
void
Scheduler::scheduleStarvationEvent()
{
if (!starvationEvent.scheduled()) {
schedule(&starvationEvent);
if (readyEvent.scheduled())
deschedule(&readyEvent);
}
}
void
Scheduler::runReady()
{
bool empty = readyList.empty();
// The evaluation phase.
do {
yield();
} while (!readyList.empty());
if (!empty)
_numCycles++;
// The update phase.
update();
// The delta phase.
for (auto &e: deltas)
e->run();
deltas.clear();
if (!runToTime && starved())
scheduleStarvationEvent();
if (runOnce)
schedulePause();
}
void
Scheduler::update()
{
Channel *channel = updateList.getNext();
while (channel) {
channel->popListNode();
channel->update();
channel = updateList.getNext();
}
}
void
Scheduler::pause()
{
_paused = true;
kernel->status(::sc_core::SC_PAUSED);
runOnce = false;
scMain->run();
}
void
Scheduler::stop()
{
_stopped = true;
kernel->stop();
clear();
runOnce = false;
scMain->run();
}
void
Scheduler::start(Tick max_tick, bool run_to_time)
{
// We should be running from sc_main. Keep track of that Fiber to return
// to later.
scMain = Fiber::currentFiber();
_started = true;
_paused = false;
_stopped = false;
runToTime = run_to_time;
maxTick = max_tick;
if (initDone) {
if (!runToTime && starved())
scheduleStarvationEvent();
kernel->status(::sc_core::SC_RUNNING);
}
schedule(&maxTickEvent, maxTick);
// Return to gem5 to let it run events, etc.
Fiber::primaryFiber()->run();
if (pauseEvent.scheduled())
deschedule(&pauseEvent);
if (stopEvent.scheduled())
deschedule(&stopEvent);
if (maxTickEvent.scheduled())
deschedule(&maxTickEvent);
if (starvationEvent.scheduled())
deschedule(&starvationEvent);
}
void
Scheduler::oneCycle()
{
runOnce = true;
scheduleReadyEvent();
start(::MaxTick, false);
}
void
Scheduler::schedulePause()
{
if (pauseEvent.scheduled())
return;
schedule(&pauseEvent);
}
void
Scheduler::scheduleStop(bool finish_delta)
{
if (stopEvent.scheduled())
return;
if (!finish_delta) {
// If we're not supposed to finish the delta cycle, flush all
// pending activity.
clear();
}
schedule(&stopEvent);
}
Scheduler scheduler;
} // namespace sc_gem5
|