Gabe Black has uploaded this change for review. (
https://gem5-review.googlesource.com/c/public/gem5/+/12031
Change subject: systemc: Implement sc_pause, sc_stop, and re-sc_start-ing.
......................................................................
systemc: Implement sc_pause, sc_stop, and re-sc_start-ing.
This change further modifies the scheduler to implement the sc_pause
and sc_stop functions, and to ensure that calling sc_start again works.
Also, some small changes were made to how processes and contexts are
hooked up. Now, rather than checking whether a process is running to
determine wether it started on its own or needs to be started manually,
there's a bool which explicitly tracks whether it needs this step. The
problem was that once a thread finished, it wasn't considered running
any more. In that case it had run but finished, but that was
indistinguishable from it needing to run but not having been started.
Change-Id: I3aefb5493f91d9efa1a1382586196339b67925fe
---
M src/systemc/core/process.cc
M src/systemc/core/process.hh
M src/systemc/core/process_types.hh
M src/systemc/core/sc_main.cc
M src/systemc/core/scheduler.cc
M src/systemc/core/scheduler.hh
6 files changed, 171 insertions(+), 28 deletions(-)
diff --git a/src/systemc/core/process.cc b/src/systemc/core/process.cc
index 63d2ff9..7ed187f 100644
--- a/src/systemc/core/process.cc
+++ b/src/systemc/core/process.cc
@@ -277,7 +277,6 @@
void
Process::run()
{
- _running = true;
bool reset;
do {
reset = false;
@@ -287,7 +286,7 @@
reset = exc.is_reset();
}
} while (reset);
- _running = false;
+ _terminated = true;
}
void
@@ -323,9 +322,10 @@
scheduler.ready(this);
}
-Process::Process(const char *name, ProcessFuncWrapper *func, bool
_dynamic) :
+Process::Process(const char *name, ProcessFuncWrapper *func,
+ bool _dynamic, bool needs_start) :
::sc_core::sc_object(name), excWrapper(nullptr), func(func),
- _running(false), _dynamic(_dynamic), _isUnwinding(false),
+ _needsStart(needs_start), _dynamic(_dynamic), _isUnwinding(false),
_terminated(false), _suspended(false), _disabled(false),
_syncReset(false), refCount(0), stackSize(::Fiber::DefaultStackSize),
dynamicSensitivity(nullptr)
diff --git a/src/systemc/core/process.hh b/src/systemc/core/process.hh
index 579ea60..7c75d62 100644
--- a/src/systemc/core/process.hh
+++ b/src/systemc/core/process.hh
@@ -246,7 +246,7 @@
{
public:
virtual ::sc_core::sc_curr_proc_kind procKind() const = 0;
- bool running() const { return _running; }
+ bool needsStart() const { return _needsStart; }
bool dynamic() const { return _dynamic; }
bool isUnwinding() const { return _isUnwinding; }
bool terminated() const { return _terminated; }
@@ -298,7 +298,8 @@
static Process *newest() { return _newest; }
protected:
- Process(const char *name, ProcessFuncWrapper *func, bool _dynamic);
+ Process(const char *name, ProcessFuncWrapper *func, bool _dynamic,
+ bool needs_start);
static Process *_newest;
@@ -314,7 +315,7 @@
ProcessFuncWrapper *func;
sc_core::sc_curr_proc_kind _procKind;
- bool _running;
+ bool _needsStart;
bool _dynamic;
bool _isUnwinding;
bool _terminated;
diff --git a/src/systemc/core/process_types.hh
b/src/systemc/core/process_types.hh
index 6d13592..369fa72 100644
--- a/src/systemc/core/process_types.hh
+++ b/src/systemc/core/process_types.hh
@@ -40,7 +40,7 @@
{
public:
Method(const char *name, ProcessFuncWrapper *func, bool
_dynamic=false) :
- Process(name, func, _dynamic)
+ Process(name, func, _dynamic, true)
{}
const char *kind() const override { return "sc_method_process"; }
@@ -56,7 +56,7 @@
{
public:
Thread(const char *name, ProcessFuncWrapper *func, bool
_dynamic=false) :
- Process(name, func, _dynamic), ctx(nullptr)
+ Process(name, func, _dynamic, false), ctx(nullptr)
{}
~Thread() { delete ctx; }
diff --git a/src/systemc/core/sc_main.cc b/src/systemc/core/sc_main.cc
index 0b385e9..120bbf9 100644
--- a/src/systemc/core/sc_main.cc
+++ b/src/systemc/core/sc_main.cc
@@ -123,9 +123,6 @@
sc_stop_mode _stop_mode = SC_STOP_FINISH_DELTA;
sc_status _status = SC_ELABORATION;
-Tick _max_tick = MaxTick;
-sc_starvation_policy _starvation = SC_EXIT_ON_STARVATION;
-
} // anonymous namespace
int
@@ -143,28 +140,29 @@
void
sc_start()
{
- _max_tick = MaxTick;
- _starvation = SC_EXIT_ON_STARVATION;
-
- // Switch back gem5.
- Fiber::primaryFiber()->run();
+ Tick now = curEventQueue() ? curEventQueue()->getCurTick() : 0;
+ sc_start(sc_time::from_value(MaxTick - now), SC_EXIT_ON_STARVATION);
}
void
sc_pause()
{
- warn("%s not implemented.\n", __PRETTY_FUNCTION__);
+ if (_status == SC_RUNNING)
+ ::sc_gem5::scheduler.schedulePause();
}
void
sc_start(const sc_time &time, sc_starvation_policy p)
{
- Tick now = curEventQueue() ? curEventQueue()->getCurTick() : 0;
- _max_tick = now + time.value();
- _starvation = p;
+ _status = SC_RUNNING;
- // Switch back to gem5.
- Fiber::primaryFiber()->run();
+ Tick now = curEventQueue() ? curEventQueue()->getCurTick() : 0;
+ ::sc_gem5::scheduler.start(now + time.value(), p == SC_RUN_TO_TIME);
+
+ if (::sc_gem5::scheduler.paused())
+ _status = SC_PAUSED;
+ else if (::sc_gem5::scheduler.stopped())
+ _status = SC_STOPPED;
}
void
@@ -187,7 +185,15 @@
void
sc_stop()
{
- warn("%s not implemented.\n", __PRETTY_FUNCTION__);
+ if (_status == SC_STOPPED)
+ return;
+
+ if (sc_is_running()) {
+ bool finish_delta = (_stop_mode == SC_STOP_FINISH_DELTA);
+ ::sc_gem5::scheduler.scheduleStop(finish_delta);
+ } else {
+ //XXX Should stop if in one of the various elaboration callbacks.
+ }
}
const sc_time &
diff --git a/src/systemc/core/scheduler.cc b/src/systemc/core/scheduler.cc
index 230ed0a..e3d275bb 100644
--- a/src/systemc/core/scheduler.cc
+++ b/src/systemc/core/scheduler.cc
@@ -37,7 +37,12 @@
{
Scheduler::Scheduler() :
- eq(nullptr), readyEvent(this, false, EventBase::Default_Pri + 1),
+ eq(nullptr), _pendingCurr(0), _pendingFuture(0),
+ readyEvent(this, false, ReadyPriority),
+ pauseEvent(this, false, PausePriority),
+ stopEvent(this, false, StopPriority),
+ scMain(nullptr), _started(false), _paused(false), _stopped(false),
+ maxTickEvent(this, false, MaxTickPriority),
_numCycles(0), _current(nullptr), initReady(false)
{}
@@ -54,6 +59,9 @@
p->ready();
}
+ if (_started)
+ eq->schedule(&maxTickEvent, maxTick);
+
initReady = true;
}
@@ -98,9 +106,8 @@
// 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 hasn't been started yet, start it. This
- // should always be true for methods, but may not be true for
threads.
- if (_current && !_current->running())
+ // If the current process needs to be manually started, start it.
+ if (_current && _current->needsStart())
_current->run();
}
}
@@ -164,6 +171,75 @@
}
}
+void
+Scheduler::pause()
+{
+ _paused = true;
+ scMain->run();
+}
+
+void
+Scheduler::stop()
+{
+ _stopped = true;
+ 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;
+
+ maxTick = max_tick;
+
+ if (initReady)
+ eq->schedule(&maxTickEvent, maxTick);
+
+ // Return to gem5 to let it run events, etc.
+ Fiber::primaryFiber()->run();
+
+ if (pauseEvent.scheduled())
+ eq->deschedule(&pauseEvent);
+ if (stopEvent.scheduled())
+ eq->deschedule(&stopEvent);
+ if (maxTickEvent.scheduled())
+ eq->deschedule(&maxTickEvent);
+}
+
+void
+Scheduler::schedulePause()
+{
+ if (pauseEvent.scheduled())
+ return;
+
+ eq->schedule(&pauseEvent, eq->getCurTick());
+}
+
+void
+Scheduler::scheduleStop(bool finish_delta)
+{
+ if (stopEvent.scheduled())
+ return;
+
+ if (!finish_delta) {
+ // If we're not supposed to finish the delta cycle, flush the list
+ // of ready processes and scheduled updates.
+ Process *p;
+ while ((p = readyList.getNext()))
+ p->popListNode();
+ Channel *c;
+ while ((c = updateList.getNext()))
+ c->popListNode();
+ }
+ eq->schedule(&stopEvent, eq->getCurTick());
+}
+
Scheduler scheduler;
} // namespace sc_gem5
diff --git a/src/systemc/core/scheduler.hh b/src/systemc/core/scheduler.hh
index aa8ec9a..5db5556 100644
--- a/src/systemc/core/scheduler.hh
+++ b/src/systemc/core/scheduler.hh
@@ -32,11 +32,14 @@
#include <vector>
+#include "base/logging.hh"
#include "sim/eventq.hh"
#include "systemc/core/channel.hh"
#include "systemc/core/list.hh"
#include "systemc/core/process.hh"
+class Fiber;
+
namespace sc_gem5
{
@@ -105,6 +108,32 @@
* will all happen together since the readyEvent priority is lower,
* potentially marking new processes as ready. Once these events finish,
the
* readyEvent may run, starting the next delta cycle.
+ *
+ * PAUSE/STOP
+ *
+ * To inject a pause from sc_pause which should happen after the current
delta
+ * cycle's delta notification phase, an event is scheduled with a lower
than
+ * normal priority, but higher than the readyEvent. That ensures that any
+ * delta notifications which are scheduled with normal priority will happen
+ * first, since those are part of the current delta cycle. Then the pause
+ * event will happen before the next readyEvent which would start the next
+ * delta cycle. All of these events are scheduled for the current time,
and so
+ * would happen before any timed notifications went off.
+ *
+ * To inject a stop from sc_stop, the delta cycles should stop before even
the
+ * delta notifications have happened, but after the evaluate and update
phases.
+ * For that, a stop event with slightly higher than normal priority will be
+ * scheduled so that it happens before any of the delta notification events
+ * which are at normal priority.
+ *
+ * MAX RUN TIME
+ *
+ * When sc_start is called, it's possible to pass in a maximum time the
+ * simulation should run to, at which point sc_pause is implicitly called.
+ * That's implemented by scheduling an event at the max time with a
priority
+ * which is lower than all the others so that it happens only if time would
+ * advance. When that event triggers, it calls the same function as the
pause
+ * event.
*/
class Scheduler
@@ -156,13 +185,44 @@
// Run scheduled channel updates.
void update();
+ void setScMainFiber(Fiber *sc_main) { scMain = sc_main; }
+
+ void start(Tick max_tick, bool run_to_time);
+
+ void schedulePause();
+ void scheduleStop(bool finish_delta);
+
+ bool paused() { return _paused; }
+ bool stopped() { return _stopped; }
+
private:
+ typedef const EventBase::Priority Priority;
+ static Priority DefaultPriority = EventBase::Default_Pri;
+
+ static Priority StopPriority = DefaultPriority - 1;
+ static Priority PausePriority = DefaultPriority + 1;
+ static Priority ReadyPriority = DefaultPriority + 2;
+ static Priority MaxTickPriority = DefaultPriority + 3;
+
EventQueue *eq;
void runReady();
EventWrapper<Scheduler, &Scheduler::runReady> readyEvent;
void scheduleReadyEvent();
+ void pause();
+ void stop();
+ EventWrapper<Scheduler, &Scheduler::pause> pauseEvent;
+ EventWrapper<Scheduler, &Scheduler::stop> stopEvent;
+ Fiber *scMain;
+
+ bool _started;
+ bool _paused;
+ bool _stopped;
+
+ Tick maxTick;
+ EventWrapper<Scheduler, &Scheduler::pause> maxTickEvent;
+
uint64_t _numCycles;
Process *_current;
--
To view, visit https://gem5-review.googlesource.com/c/public/gem5/+/12031
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Gerrit-Project: public/gem5
Gerrit-Branch: master
Gerrit-Change-Id: I3aefb5493f91d9efa1a1382586196339b67925fe
Gerrit-Change-Number: 12031
Gerrit-PatchSet: 1
Gerrit-Owner: Gabe Black <[email protected]>
Gerrit-MessageType: newchange
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