e5e5b80690
This patch fixes checkpoint restore in the SystemC hosting example by handling
early PollEvent events correctly before any EventQueue events are posted.
The SystemC event queue handler (SCEventQueue) reports an error if the event
loop is entered with no Events posted. It is possible for this to happen
after instantiate due to PollEvent events. This patch separates out
`external' events into a different handler in sc_module.cc to prevent the
error from occurring.
This fix also improves the event handling of asynchronous events by:
1) Making asynchronous events 'catch up' gem5 time to SystemC
time to avoid the appearance that events have been lost
while servicing an asynchronous event that schedules an
event loop exit event
2) Add an in_simulate data member to Module to allow the event
loop to check whether events should be processed or deferred
until the next time Module::simulate is entered
3) Cancel pending events around the entry/exit of the event loop
in Module::simulate
4) Moving the state initialisation of the example entirely into
run to correct a problem with early events in checkpoint
restore.
It is still possible to schedule asynchronous events (and talk PollQueue
actions) while simulate is not running. This behaviour may stil cause
some problems.
164 lines
6 KiB
C++
164 lines
6 KiB
C++
/*
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* Copyright (c) 2014 ARM Limited
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* All rights reserved
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*
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* The license below extends only to copyright in the software and shall
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* not be construed as granting a license to any other intellectual
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* property including but not limited to intellectual property relating
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* to a hardware implementation of the functionality of the software
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* licensed hereunder. You may use the software subject to the license
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* terms below provided that you ensure that this notice is replicated
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* unmodified and in its entirety in all distributions of the software,
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* modified or unmodified, in source code or in binary form.
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*
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* Copyright (c) 2006 The Regents of The University of Michigan
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* Copyright (c) 2013 Advanced Micro Devices, Inc.
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* Copyright (c) 2013 Mark D. Hill and David A. Wood
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Authors: Nathan Binkert
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* Steve Reinhardt
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* Andrew Bardsley
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*/
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/**
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* @file
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*
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* Defines an sc_module type to wrap a gem5 simulation. The 'evaluate'
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* thread on that module implements the gem5 event loop.
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*
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* This currently only supports a single event queue and strictly
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* cooperatively threaded SystemC threads and so there should be at
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* most one Gem5Module instantiated in any simulation.
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*/
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#ifndef __SIM_SC_MODULE_HH__
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#define __SIM_SC_MODULE_HH__
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#include <systemc>
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#include "sim/eventq.hh"
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#include "sim/sim_events.hh"
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namespace Gem5SystemC
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{
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/** A SystemC module implementing the gem5 event queue. This object
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* doesn't actually own any of the simulation SimObjects (those need
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* to be administered separately) but it does control the event
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* queue.
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*
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* The event loop here services gem5 events in order at the current time
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* and then yielding to another SystemC thread. gem5 events are not
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* individually scheduled in SystemC. For this reason, asynchronous events
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* and function interaction (for example TLM) with gem5 from SystemC must
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* notify the module so that the yielding 'wait' can be interrupted.
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* From the point of view of another SystemC module calling into gem5,
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* curTick can lag SystemC time, be exactly the same time but *never*
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* lead SystemC time.
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*
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* This functionality is wrapped in an sc_module as its intended that
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* the a class representing top level simulation control should be derived
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* from this class. */
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class Module : public sc_core::sc_module
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{
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protected:
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/** Event to trigger (via. ::notify) for event scheduling from
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* outside gem5 */
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sc_core::sc_event externalSchedulingEvent;
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/** Event to trigger on exit of eventLoop */
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sc_core::sc_event eventLoopExitEvent;
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/** Event to trigger to enter eventLoop */
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sc_core::sc_event eventLoopEnterEvent;
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/** Expected exit time of last eventLoop sleep */
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Tick wait_exit_time;
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/** Are we in Module::simulate? Used to mask events when not inside
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* the simulate loop */
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bool in_simulate;
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/** Placeholder base class for a variant event queue if this becomes
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* useful */
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class SCEventQueue : public EventQueue
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{
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protected:
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Module &module;
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public:
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SCEventQueue(const std::string &name,
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Module &module_) : EventQueue(name), module(module_)
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{ }
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/** Signal module to wakeup */
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void wakeup(Tick when);
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};
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/** Service any async event marked up in the globals event_... */
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void serviceAsyncEvent();
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public:
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/** Simulate is a process */
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SC_HAS_PROCESS(Module);
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Module(sc_core::sc_module_name name);
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/** Last exitEvent from eventLoop */
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Event *exitEvent;
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/** Setup global event queues. Call this before any other event queues
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* are created */
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static void setupEventQueues(Module &module);
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/** Catch gem5 time up with SystemC */
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void catchup();
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/** Notify an externalSchedulingEvent at the given time from the
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* current SystemC time */
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void notify(sc_core::sc_time time_from_now = sc_core::SC_ZERO_TIME);
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/** Process an event triggered by externalSchedulingEvent and also
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* call eventLoop (to try and mop up any events at this time) if there
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* are any scheduled events */
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void serviceExternalEvent();
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/** Process gem5 events up until an exit event or there are no events
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* left. */
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void eventLoop();
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/** Run eventLoop up to num_cycles and return the final event */
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GlobalSimLoopExitEvent *simulate(Tick num_cycles = MaxTick);
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};
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/** There are assumptions throughout Gem5SystemC file that a tick is 1ps.
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* Make this the case */
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void setTickFrequency();
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}
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#endif // __SIM_SC_MODULE_HH__
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