scheduler.cc revision 13245:c666c5d4996b 
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#include "systemc/utils/tracefile.hh"
40
41namespace sc_gem5
42{
43
44Scheduler::Scheduler() :
45    eq(nullptr), readyEvent(this, false, ReadyPriority),
46    pauseEvent(this, false, PausePriority),
47    stopEvent(this, false, StopPriority),
48    scMain(nullptr), _throwToScMain(nullptr),
49    starvationEvent(this, false, StarvationPriority),
50    _elaborationDone(false), _started(false), _stopNow(false),
51    _status(StatusOther), maxTickEvent(this, false, MaxTickPriority),
52    timeAdvancesEvent(this, false, TimeAdvancesPriority), _numCycles(0),
53    _changeStamp(0), _current(nullptr), initDone(false), runOnce(false)
54{}
55
56Scheduler::~Scheduler()
57{
58    // Clear out everything that belongs to us to make sure nobody tries to
59    // clear themselves out after the scheduler goes away.
60    clear();
61}
62
63void
64Scheduler::clear()
65{
66    // Delta notifications.
67    while (!deltas.empty())
68        deltas.front()->deschedule();
69
70    // Timed notifications.
71    for (auto &tsp: timeSlots) {
72        TimeSlot *&ts = tsp.second;
73        while (!ts->events.empty())
74            ts->events.front()->deschedule();
75        deschedule(ts);
76    }
77    timeSlots.clear();
78
79    // gem5 events.
80    if (readyEvent.scheduled())
81        deschedule(&readyEvent);
82    if (pauseEvent.scheduled())
83        deschedule(&pauseEvent);
84    if (stopEvent.scheduled())
85        deschedule(&stopEvent);
86    if (starvationEvent.scheduled())
87        deschedule(&starvationEvent);
88    if (maxTickEvent.scheduled())
89        deschedule(&maxTickEvent);
90    if (timeAdvancesEvent.scheduled())
91        deschedule(&timeAdvancesEvent);
92
93    Process *p;
94    while ((p = initList.getNext()))
95        p->popListNode();
96    while ((p = readyListMethods.getNext()))
97        p->popListNode();
98    while ((p = readyListThreads.getNext()))
99        p->popListNode();
100
101    Channel *c;
102    while ((c = updateList.getNext()))
103        c->popListNode();
104}
105
106void
107Scheduler::initPhase()
108{
109    for (Process *p = initList.getNext(); p; p = initList.getNext()) {
110        p->popListNode();
111
112        if (p->dontInitialize()) {
113            if (!p->hasStaticSensitivities() && !p->internal()) {
114                SC_REPORT_WARNING(
115                        "(W558) disable() or dont_initialize() called on "
116                        "process with no static sensitivity, it will be "
117                        "orphaned", p->name());
118            }
119        } else {
120            p->ready();
121        }
122    }
123
124    runUpdate();
125    runDelta();
126
127    for (auto ets: eventsToSchedule)
128        eq->schedule(ets.first, ets.second);
129    eventsToSchedule.clear();
130
131    if (_started) {
132        if (!runToTime && starved())
133            scheduleStarvationEvent();
134        kernel->status(::sc_core::SC_RUNNING);
135    }
136
137    initDone = true;
138
139    status(StatusOther);
140
141    scheduleTimeAdvancesEvent();
142}
143
144void
145Scheduler::reg(Process *p)
146{
147    if (initDone) {
148        // If not marked as dontInitialize, mark as ready.
149        if (!p->dontInitialize())
150            p->ready();
151    } else {
152        // Otherwise, record that this process should be initialized once we
153        // get there.
154        initList.pushLast(p);
155    }
156}
157
158void
159Scheduler::yield()
160{
161    // Pull a process from the active list.
162    _current = getNextReady();
163    if (!_current) {
164        // There are no more processes, so return control to evaluate.
165        Fiber::primaryFiber()->run();
166    } else {
167        _current->popListNode();
168        // Switch to whatever Fiber is supposed to run this process. All
169        // Fibers which aren't running should be parked at this line.
170        _current->fiber()->run();
171        // If the current process needs to be manually started, start it.
172        if (_current && _current->needsStart()) {
173            _current->needsStart(false);
174            try {
175                _current->run();
176            } catch (...) {
177                throwToScMain();
178            }
179        }
180    }
181    if (_current && _current->excWrapper) {
182        // Make sure this isn't a method process.
183        assert(!_current->needsStart());
184        auto ew = _current->excWrapper;
185        _current->excWrapper = nullptr;
186        ew->throw_it();
187    }
188}
189
190void
191Scheduler::ready(Process *p)
192{
193    if (_stopNow)
194        return;
195
196    if (p->procKind() == ::sc_core::SC_METHOD_PROC_)
197        readyListMethods.pushLast(p);
198    else
199        readyListThreads.pushLast(p);
200
201    if (!inEvaluate())
202        scheduleReadyEvent();
203}
204
205void
206Scheduler::resume(Process *p)
207{
208    if (initDone)
209        ready(p);
210    else
211        initList.pushLast(p);
212}
213
214bool
215listContains(ListNode *list, ListNode *target)
216{
217    ListNode *n = list->nextListNode;
218    while (n != list)
219        if (n == target)
220            return true;
221    return false;
222}
223
224bool
225Scheduler::suspend(Process *p)
226{
227    bool was_ready;
228    if (initDone) {
229        // After initialization, check if we're on a ready list.
230        was_ready = (p->nextListNode != nullptr);
231        p->popListNode();
232    } else {
233        // Nothing is ready before init.
234        was_ready = false;
235    }
236    return was_ready;
237}
238
239void
240Scheduler::requestUpdate(Channel *c)
241{
242    updateList.pushLast(c);
243    if (!inEvaluate())
244        scheduleReadyEvent();
245}
246
247void
248Scheduler::scheduleReadyEvent()
249{
250    // Schedule the evaluate and update phases.
251    if (!readyEvent.scheduled()) {
252        schedule(&readyEvent);
253        if (starvationEvent.scheduled())
254            deschedule(&starvationEvent);
255    }
256}
257
258void
259Scheduler::scheduleStarvationEvent()
260{
261    if (!starvationEvent.scheduled()) {
262        schedule(&starvationEvent);
263        if (readyEvent.scheduled())
264            deschedule(&readyEvent);
265    }
266}
267
268void
269Scheduler::runReady()
270{
271    scheduleTimeAdvancesEvent();
272
273    bool empty = readyListMethods.empty() && readyListThreads.empty();
274    lastReadyTick = getCurTick();
275
276    // The evaluation phase.
277    status(StatusEvaluate);
278    do {
279        yield();
280    } while (getNextReady());
281
282    if (!empty) {
283        _numCycles++;
284        _changeStamp++;
285    }
286
287    if (_stopNow) {
288        status(StatusOther);
289        return;
290    }
291
292    runUpdate();
293    if (!traceFiles.empty())
294        trace(true);
295    runDelta();
296
297    if (!runToTime && starved())
298        scheduleStarvationEvent();
299
300    if (runOnce)
301        schedulePause();
302
303    status(StatusOther);
304}
305
306void
307Scheduler::runUpdate()
308{
309    status(StatusUpdate);
310
311    try {
312        Channel *channel = updateList.getNext();
313        while (channel) {
314            channel->popListNode();
315            channel->update();
316            channel = updateList.getNext();
317        }
318    } catch (...) {
319        throwToScMain();
320    }
321}
322
323void
324Scheduler::runDelta()
325{
326    status(StatusDelta);
327
328    try {
329        while (!deltas.empty())
330            deltas.front()->run();
331    } catch (...) {
332        throwToScMain();
333    }
334}
335
336void
337Scheduler::pause()
338{
339    status(StatusPaused);
340    kernel->status(::sc_core::SC_PAUSED);
341    runOnce = false;
342    if (scMain && !scMain->finished())
343        scMain->run();
344}
345
346void
347Scheduler::stop()
348{
349    status(StatusStopped);
350    kernel->stop();
351
352    clear();
353
354    runOnce = false;
355    if (scMain && !scMain->finished())
356        scMain->run();
357}
358
359void
360Scheduler::start(Tick max_tick, bool run_to_time)
361{
362    // We should be running from sc_main. Keep track of that Fiber to return
363    // to later.
364    scMain = Fiber::currentFiber();
365
366    _started = true;
367    status(StatusOther);
368    runToTime = run_to_time;
369
370    maxTick = max_tick;
371    lastReadyTick = getCurTick();
372
373    if (initDone) {
374        if (!runToTime && starved())
375            scheduleStarvationEvent();
376        kernel->status(::sc_core::SC_RUNNING);
377    }
378
379    schedule(&maxTickEvent, maxTick);
380    scheduleTimeAdvancesEvent();
381
382    // Return to gem5 to let it run events, etc.
383    Fiber::primaryFiber()->run();
384
385    if (pauseEvent.scheduled())
386        deschedule(&pauseEvent);
387    if (stopEvent.scheduled())
388        deschedule(&stopEvent);
389    if (maxTickEvent.scheduled())
390        deschedule(&maxTickEvent);
391    if (starvationEvent.scheduled())
392        deschedule(&starvationEvent);
393
394    if (_throwToScMain) {
395        const ::sc_core::sc_report *to_throw = _throwToScMain;
396        _throwToScMain = nullptr;
397        throw *to_throw;
398    }
399}
400
401void
402Scheduler::oneCycle()
403{
404    runOnce = true;
405    scheduleReadyEvent();
406    start(::MaxTick, false);
407}
408
409void
410Scheduler::schedulePause()
411{
412    if (pauseEvent.scheduled())
413        return;
414
415    schedule(&pauseEvent);
416}
417
418void
419Scheduler::throwToScMain(const ::sc_core::sc_report *r)
420{
421    if (!r)
422        r = reportifyException();
423    _throwToScMain = r;
424    status(StatusOther);
425    scMain->run();
426}
427
428void
429Scheduler::scheduleStop(bool finish_delta)
430{
431    if (stopEvent.scheduled())
432        return;
433
434    if (!finish_delta) {
435        _stopNow = true;
436        // If we're not supposed to finish the delta cycle, flush all
437        // pending activity.
438        clear();
439    }
440    schedule(&stopEvent);
441}
442
443void
444Scheduler::trace(bool delta)
445{
446    for (auto tf: traceFiles)
447        tf->trace(delta);
448}
449
450Scheduler scheduler;
451
452namespace {
453
454void
455throwingReportHandler(const ::sc_core::sc_report &r,
456                      const ::sc_core::sc_actions &)
457{
458    throw r;
459}
460
461} // anonymous namespace
462
463const ::sc_core::sc_report *
464reportifyException()
465{
466    ::sc_core::sc_report_handler_proc old_handler =
467        ::sc_core::sc_report_handler::get_handler();
468    ::sc_core::sc_report_handler::set_handler(&throwingReportHandler);
469
470    try {
471        try {
472            // Rethrow the current exception so we can catch it and throw an
473            // sc_report instead if it's not a type we recognize/can handle.
474            throw;
475        } catch (const ::sc_core::sc_report &) {
476            // It's already a sc_report, so nothing to do.
477            throw;
478        } catch (const ::sc_core::sc_unwind_exception &) {
479            panic("Kill/reset exception escaped a Process::run()");
480        } catch (const std::exception &e) {
481            SC_REPORT_ERROR("uncaught exception", e.what());
482        } catch (const char *msg) {
483            SC_REPORT_ERROR("uncaught exception", msg);
484        } catch (...) {
485            SC_REPORT_ERROR("uncaught exception", "UNKNOWN EXCEPTION");
486        }
487    } catch (const ::sc_core::sc_report &r) {
488        ::sc_core::sc_report_handler::set_handler(old_handler);
489        return &r;
490    }
491    panic("No exception thrown in reportifyException.");
492}
493
494} // namespace sc_gem5
495