/*
* Copyright (c) 2000-2005 The Regents of The University of Michigan
+ * Copyright (c) 2013 Advanced Micro Devices, Inc.
+ * Copyright (c) 2013 Mark D. Hill and David A. Wood
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
#include <cassert>
#include <climits>
#include <iosfwd>
+#include <memory>
+#include <mutex>
#include <string>
#include "base/flags.hh"
#include "base/misc.hh"
-#include "base/trace.hh"
#include "base/types.hh"
#include "debug/Event.hh"
#include "sim/serialize.hh"
class EventQueue; // forward declaration
+class BaseGlobalEvent;
-extern EventQueue mainEventQueue;
+//! Simulation Quantum for multiple eventq simulation.
+//! The quantum value is the period length after which the queues
+//! synchronize themselves with each other. This means that any
+//! event to scheduled on Queue A which is generated by an event on
+//! Queue B should be at least simQuantum ticks away in future.
+extern Tick simQuantum;
-/*
- * An item on an event queue. The action caused by a given
- * event is specified by deriving a subclass and overriding the
- * process() member function.
- *
- * Caution, the order of members is chosen to maximize data packing.
+//! Current number of allocated main event queues.
+extern uint32_t numMainEventQueues;
+
+//! Array for main event queues.
+extern std::vector<EventQueue *> mainEventQueue;
+
+#ifndef SWIG
+//! The current event queue for the running thread. Access to this queue
+//! does not require any locking from the thread.
+
+extern __thread EventQueue *_curEventQueue;
+
+#endif
+
+//! Current mode of execution: parallel / serial
+extern bool inParallelMode;
+
+//! Function for returning eventq queue for the provided
+//! index. The function allocates a new queue in case one
+//! does not exist for the index, provided that the index
+//! is with in bounds.
+EventQueue *getEventQueue(uint32_t index);
+
+inline EventQueue *curEventQueue() { return _curEventQueue; }
+inline void curEventQueue(EventQueue *q) { _curEventQueue = q; }
+
+/**
+ * Common base class for Event and GlobalEvent, so they can share flag
+ * and priority definitions and accessor functions. This class should
+ * not be used directly.
*/
-class Event : public Serializable
+class EventBase
{
- friend class EventQueue;
-
protected:
typedef unsigned short FlagsType;
typedef ::Flags<FlagsType> Flags;
static const FlagsType Initialized = 0x7a40; // somewhat random bits
static const FlagsType InitMask = 0xffc0; // mask for init bits
- bool
- initialized() const
- {
- return this && (flags & InitMask) == Initialized;
- }
-
public:
typedef int8_t Priority;
+ /// Event priorities, to provide tie-breakers for events scheduled
+ /// at the same cycle. Most events are scheduled at the default
+ /// priority; these values are used to control events that need to
+ /// be ordered within a cycle.
+
+ /// Minimum priority
+ static const Priority Minimum_Pri = SCHAR_MIN;
+
+ /// If we enable tracing on a particular cycle, do that as the
+ /// very first thing so we don't miss any of the events on
+ /// that cycle (even if we enter the debugger).
+ static const Priority Debug_Enable_Pri = -101;
+
+ /// Breakpoints should happen before anything else (except
+ /// enabling trace output), so we don't miss any action when
+ /// debugging.
+ static const Priority Debug_Break_Pri = -100;
+
+ /// CPU switches schedule the new CPU's tick event for the
+ /// same cycle (after unscheduling the old CPU's tick event).
+ /// The switch needs to come before any tick events to make
+ /// sure we don't tick both CPUs in the same cycle.
+ static const Priority CPU_Switch_Pri = -31;
+
+ /// For some reason "delayed" inter-cluster writebacks are
+ /// scheduled before regular writebacks (which have default
+ /// priority). Steve?
+ static const Priority Delayed_Writeback_Pri = -1;
+
+ /// Default is zero for historical reasons.
+ static const Priority Default_Pri = 0;
+
+ /// DVFS update event leads to stats dump therefore given a lower priority
+ /// to ensure all relevant states have been updated
+ static const Priority DVFS_Update_Pri = 31;
+
+ /// Serailization needs to occur before tick events also, so
+ /// that a serialize/unserialize is identical to an on-line
+ /// CPU switch.
+ static const Priority Serialize_Pri = 32;
+
+ /// CPU ticks must come after other associated CPU events
+ /// (such as writebacks).
+ static const Priority CPU_Tick_Pri = 50;
+
+ /// Statistics events (dump, reset, etc.) come after
+ /// everything else, but before exit.
+ static const Priority Stat_Event_Pri = 90;
+
+ /// Progress events come at the end.
+ static const Priority Progress_Event_Pri = 95;
+
+ /// If we want to exit on this cycle, it's the very last thing
+ /// we do.
+ static const Priority Sim_Exit_Pri = 100;
+
+ /// Maximum priority
+ static const Priority Maximum_Pri = SCHAR_MAX;
+};
+
+/*
+ * An item on an event queue. The action caused by a given
+ * event is specified by deriving a subclass and overriding the
+ * process() member function.
+ *
+ * Caution, the order of members is chosen to maximize data packing.
+ */
+class Event : public EventBase, public Serializable
+{
+ friend class EventQueue;
+
private:
// The event queue is now a linked list of linked lists. The
// 'nextBin' pointer is to find the bin, where a bin is defined as
#endif
}
+ bool
+ initialized() const
+ {
+ return (flags & InitMask) == Initialized;
+ }
+
protected:
/// Accessor for flags.
Flags
virtual void trace(const char *action); //!< trace event activity
public:
- /// Event priorities, to provide tie-breakers for events scheduled
- /// at the same cycle. Most events are scheduled at the default
- /// priority; these values are used to control events that need to
- /// be ordered within a cycle.
-
- /// Minimum priority
- static const Priority Minimum_Pri = SCHAR_MIN;
-
- /// If we enable tracing on a particular cycle, do that as the
- /// very first thing so we don't miss any of the events on
- /// that cycle (even if we enter the debugger).
- static const Priority Trace_Enable_Pri = -101;
-
- /// Breakpoints should happen before anything else (except
- /// enabling trace output), so we don't miss any action when
- /// debugging.
- static const Priority Debug_Break_Pri = -100;
-
- /// CPU switches schedule the new CPU's tick event for the
- /// same cycle (after unscheduling the old CPU's tick event).
- /// The switch needs to come before any tick events to make
- /// sure we don't tick both CPUs in the same cycle.
- static const Priority CPU_Switch_Pri = -31;
-
- /// For some reason "delayed" inter-cluster writebacks are
- /// scheduled before regular writebacks (which have default
- /// priority). Steve?
- static const Priority Delayed_Writeback_Pri = -1;
-
- /// Default is zero for historical reasons.
- static const Priority Default_Pri = 0;
-
- /// Serailization needs to occur before tick events also, so
- /// that a serialize/unserialize is identical to an on-line
- /// CPU switch.
- static const Priority Serialize_Pri = 32;
-
- /// CPU ticks must come after other associated CPU events
- /// (such as writebacks).
- static const Priority CPU_Tick_Pri = 50;
-
- /// Statistics events (dump, reset, etc.) come after
- /// everything else, but before exit.
- static const Priority Stat_Event_Pri = 90;
-
- /// Progress events come at the end.
- static const Priority Progress_Event_Pri = 95;
-
- /// If we want to exit on this cycle, it's the very last thing
- /// we do.
- static const Priority Sim_Exit_Pri = 100;
-
- /// Maximum priority
- static const Priority Maximum_Pri = SCHAR_MAX;
/*
* Event constructor
* @param queue that the event gets scheduled on
*/
Event(Priority p = Default_Pri, Flags f = 0)
- : nextBin(NULL), nextInBin(NULL), _priority(p),
+ : nextBin(nullptr), nextInBin(nullptr), _when(0), _priority(p),
flags(Initialized | f)
{
assert(f.noneSet(~PublicWrite));
/// See if this is a SimExitEvent (without resorting to RTTI)
bool isExitEvent() const { return flags.isSet(IsExitEvent); }
+ /// Check whether this event will auto-delete
+ bool isAutoDelete() const { return flags.isSet(AutoDelete); }
+
/// Get the time that the event is scheduled
Tick when() const { return _when; }
/// Get the event priority
Priority priority() const { return _priority; }
-#ifndef SWIG
- struct priority_compare
- : public std::binary_function<Event *, Event *, bool>
- {
- bool
- operator()(const Event *l, const Event *r) const
- {
- return l->when() >= r->when() || l->priority() >= r->priority();
- }
- };
+ //! If this is part of a GlobalEvent, return the pointer to the
+ //! Global Event. By default, there is no GlobalEvent, so return
+ //! NULL. (Overridden in GlobalEvent::BarrierEvent.)
+ virtual BaseGlobalEvent *globalEvent() { return NULL; }
- virtual void serialize(std::ostream &os);
- virtual void unserialize(Checkpoint *cp, const std::string §ion);
+#ifndef SWIG
+ void serialize(CheckpointOut &cp) const M5_ATTR_OVERRIDE;
+ void unserialize(CheckpointIn &cp) M5_ATTR_OVERRIDE;
#endif
};
}
#endif
-/*
+/**
* Queue of events sorted in time order
+ *
+ * Events are scheduled (inserted into the event queue) using the
+ * schedule() method. This method either inserts a <i>synchronous</i>
+ * or <i>asynchronous</i> event.
+ *
+ * Synchronous events are scheduled using schedule() method with the
+ * argument 'global' set to false (default). This should only be done
+ * from a thread holding the event queue lock
+ * (EventQueue::service_mutex). The lock is always held when an event
+ * handler is called, it can therefore always insert events into its
+ * own event queue unless it voluntarily releases the lock.
+ *
+ * Events can be scheduled across thread (and event queue borders) by
+ * either scheduling asynchronous events or taking the target event
+ * queue's lock. However, the lock should <i>never</i> be taken
+ * directly since this is likely to cause deadlocks. Instead, code
+ * that needs to schedule events in other event queues should
+ * temporarily release its own queue and lock the new queue. This
+ * prevents deadlocks since a single thread never owns more than one
+ * event queue lock. This functionality is provided by the
+ * ScopedMigration helper class. Note that temporarily migrating
+ * between event queues can make the simulation non-deterministic, it
+ * should therefore be limited to cases where that can be tolerated
+ * (e.g., handling asynchronous IO or fast-forwarding in KVM).
+ *
+ * Asynchronous events can also be scheduled using the normal
+ * schedule() method with the 'global' parameter set to true. Unlike
+ * the previous queue migration strategy, this strategy is fully
+ * deterministic. This causes the event to be inserted in a separate
+ * queue of asynchronous events (async_queue), which is merged main
+ * event queue at the end of each simulation quantum (by calling the
+ * handleAsyncInsertions() method). Note that this implies that such
+ * events must happen at least one simulation quantum into the future,
+ * otherwise they risk being scheduled in the past by
+ * handleAsyncInsertions().
*/
class EventQueue : public Serializable
{
private:
std::string objName;
Event *head;
+ Tick _curTick;
+
+ //! Mutex to protect async queue.
+ std::mutex async_queue_mutex;
+
+ //! List of events added by other threads to this event queue.
+ std::list<Event*> async_queue;
+
+ /**
+ * Lock protecting event handling.
+ *
+ * This lock is always taken when servicing events. It is assumed
+ * that the thread scheduling new events (not asynchronous events
+ * though) have taken this lock. This is normally done by
+ * serviceOne() since new events are typically scheduled as a
+ * response to an earlier event.
+ *
+ * This lock is intended to be used to temporarily steal an event
+ * queue to support inter-thread communication when some
+ * deterministic timing can be sacrificed for speed. For example,
+ * the KVM CPU can use this support to access devices running in a
+ * different thread.
+ *
+ * @see EventQueue::ScopedMigration.
+ * @see EventQueue::ScopedRelease
+ * @see EventQueue::lock()
+ * @see EventQueue::unlock()
+ */
+ std::mutex service_mutex;
+ //! Insert / remove event from the queue. Should only be called
+ //! by thread operating this queue.
void insert(Event *event);
void remove(Event *event);
+ //! Function for adding events to the async queue. The added events
+ //! are added to main event queue later. Threads, other than the
+ //! owning thread, should call this function instead of insert().
+ void asyncInsert(Event *event);
+
EventQueue(const EventQueue &);
- const EventQueue &operator=(const EventQueue &);
public:
+#ifndef SWIG
+ /**
+ * Temporarily migrate execution to a different event queue.
+ *
+ * An instance of this class temporarily migrates execution to a
+ * different event queue by releasing the current queue, locking
+ * the new queue, and updating curEventQueue(). This can, for
+ * example, be useful when performing IO across thread event
+ * queues when timing is not crucial (e.g., during fast
+ * forwarding).
+ */
+ class ScopedMigration
+ {
+ public:
+ ScopedMigration(EventQueue *_new_eq)
+ : new_eq(*_new_eq), old_eq(*curEventQueue())
+ {
+ old_eq.unlock();
+ new_eq.lock();
+ curEventQueue(&new_eq);
+ }
+
+ ~ScopedMigration()
+ {
+ new_eq.unlock();
+ old_eq.lock();
+ curEventQueue(&old_eq);
+ }
+
+ private:
+ EventQueue &new_eq;
+ EventQueue &old_eq;
+ };
+
+ /**
+ * Temporarily release the event queue service lock.
+ *
+ * There are cases where it is desirable to temporarily release
+ * the event queue lock to prevent deadlocks. For example, when
+ * waiting on the global barrier, we need to release the lock to
+ * prevent deadlocks from happening when another thread tries to
+ * temporarily take over the event queue waiting on the barrier.
+ */
+ class ScopedRelease
+ {
+ public:
+ ScopedRelease(EventQueue *_eq)
+ : eq(*_eq)
+ {
+ eq.unlock();
+ }
+
+ ~ScopedRelease()
+ {
+ eq.lock();
+ }
+
+ private:
+ EventQueue &eq;
+ };
+#endif
+
EventQueue(const std::string &n);
virtual const std::string name() const { return objName; }
+ void name(const std::string &st) { objName = st; }
- // schedule the given event on this queue
- void schedule(Event *event, Tick when);
+ //! Schedule the given event on this queue. Safe to call from any
+ //! thread.
+ void schedule(Event *event, Tick when, bool global = false);
+
+ //! Deschedule the specified event. Should be called only from the
+ //! owning thread.
void deschedule(Event *event);
+
+ //! Reschedule the specified event. Should be called only from
+ //! the owning thread.
void reschedule(Event *event, Tick when, bool always = false);
Tick nextTick() const { return head->when(); }
+ void setCurTick(Tick newVal) { _curTick = newVal; }
+ Tick getCurTick() { return _curTick; }
+ Event *getHead() const { return head; }
+
Event *serviceOne();
// process all events up to the given timestamp. we inline a
//assert(head->when() >= when && "event scheduled in the past");
serviceOne();
}
+
+ setCurTick(when);
}
// return true if no events are queued
bool debugVerify() const;
+ //! Function for moving events from the async_queue to the main queue.
+ void handleAsyncInsertions();
+
+ /**
+ * Function to signal that the event loop should be woken up because
+ * an event has been scheduled by an agent outside the gem5 event
+ * loop(s) whose event insertion may not have been noticed by gem5.
+ * This function isn't needed by the usual gem5 event loop but may
+ * be necessary in derived EventQueues which host gem5 onto other
+ * schedulers.
+ *
+ * @param when Time of a delayed wakeup (if known). This parameter
+ * can be used by an implementation to schedule a wakeup in the
+ * future if it is sure it will remain active until then.
+ * Or it can be ignored and the event queue can be woken up now.
+ */
+ virtual void wakeup(Tick when = (Tick)-1) { }
+
/**
* function for replacing the head of the event queue, so that a
* different set of events can run without disturbing events that have
*/
Event* replaceHead(Event* s);
+ /**@{*/
+ /**
+ * Provide an interface for locking/unlocking the event queue.
+ *
+ * @warn Do NOT use these methods directly unless you really know
+ * what you are doing. Incorrect use can easily lead to simulator
+ * deadlocks.
+ *
+ * @see EventQueue::ScopedMigration.
+ * @see EventQueue::ScopedRelease
+ * @see EventQueue
+ */
+ void lock() { service_mutex.lock(); }
+ void unlock() { service_mutex.unlock(); }
+ /**@}*/
+
#ifndef SWIG
- virtual void serialize(std::ostream &os);
- virtual void unserialize(Checkpoint *cp, const std::string §ion);
+ void serialize(CheckpointOut &cp) const M5_ATTR_OVERRIDE;
+ void unserialize(CheckpointIn &cp) M5_ATTR_OVERRIDE;
#endif
+
+ /**
+ * Reschedule an event after a checkpoint.
+ *
+ * Since events don't know which event queue they belong to,
+ * parent objects need to reschedule events themselves. This
+ * method conditionally schedules an event that has the Scheduled
+ * flag set. It should be called by parent objects after
+ * unserializing an object.
+ *
+ * @warn Only use this method after unserializing an Event.
+ */
+ void checkpointReschedule(Event *event);
+
+ virtual ~EventQueue() { }
};
+void dumpMainQueue();
+
#ifndef SWIG
class EventManager
{
EventQueue *eventq;
public:
- EventManager(EventManager &em) : eventq(em.queue()) {}
- EventManager(EventManager *em) : eventq(em ? em->queue() : NULL) {}
+ EventManager(EventManager &em) : eventq(em.eventq) {}
+ EventManager(EventManager *em) : eventq(em->eventq) {}
EventManager(EventQueue *eq) : eventq(eq) {}
EventQueue *
- queue() const
- {
- return eventq;
- }
-
- operator EventQueue *() const
+ eventQueue() const
{
return eventq;
}
{
eventq->reschedule(event, when, always);
}
-};
-inline void
-EventQueue::schedule(Event *event, Tick when)
-{
- // Typecasting Tick->Utick here since gcc
- // complains about signed overflow
- assert((UTick)when >= (UTick)curTick());
- assert(!event->scheduled());
- assert(event->initialized());
-
- event->setWhen(when, this);
- insert(event);
- event->flags.set(Event::Scheduled);
- if (this == &mainEventQueue)
- event->flags.set(Event::IsMainQueue);
- else
- event->flags.clear(Event::IsMainQueue);
-
- if (DTRACE(Event))
- event->trace("scheduled");
-}
-
-inline void
-EventQueue::deschedule(Event *event)
-{
- assert(event->scheduled());
- assert(event->initialized());
-
- remove(event);
-
- event->flags.clear(Event::Squashed);
- event->flags.clear(Event::Scheduled);
-
- if (DTRACE(Event))
- event->trace("descheduled");
-
- if (event->flags.isSet(Event::AutoDelete))
- delete event;
-}
+ void wakeupEventQueue(Tick when = (Tick)-1)
+ {
+ eventq->wakeup(when);
+ }
-inline void
-EventQueue::reschedule(Event *event, Tick when, bool always)
-{
- // Typecasting Tick->Utick here since gcc
- // complains about signed overflow
- assert((UTick)when >= (UTick)curTick());
- assert(always || event->scheduled());
- assert(event->initialized());
-
- if (event->scheduled())
- remove(event);
-
- event->setWhen(when, this);
- insert(event);
- event->flags.clear(Event::Squashed);
- event->flags.set(Event::Scheduled);
- if (this == &mainEventQueue)
- event->flags.set(Event::IsMainQueue);
- else
- event->flags.clear(Event::IsMainQueue);
-
- if (DTRACE(Event))
- event->trace("rescheduled");
-}
+ void setCurTick(Tick newVal) { eventq->setCurTick(newVal); }
+};
template <class T, void (T::* F)()>
void
projects / gem5.git / blobdiff