root.cc revision 11077:fae097742b7e 
1/*
2 * Copyright (c) 2002-2005 The Regents of The University of Michigan
3 * Copyright (c) 2011 Advanced Micro Devices, Inc.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are
8 * met: redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer;
10 * redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution;
13 * neither the name of the copyright holders nor the names of its
14 * contributors may be used to endorse or promote products derived from
15 * this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 * Authors: Nathan Binkert
30 *          Steve Reinhardt
31 *          Gabe Black
32 */
33
34#include "base/misc.hh"
35#include "base/trace.hh"
36#include "config/the_isa.hh"
37#include "debug/TimeSync.hh"
38#include "sim/full_system.hh"
39#include "sim/root.hh"
40
41Root *Root::_root = NULL;
42
43/*
44 * This function is called periodically by an event in M5 and ensures that
45 * at least as much real time has passed between invocations as simulated time.
46 * If not, the function either sleeps, or if the difference is small enough
47 * spin waits.
48 */
49void
50Root::timeSync()
51{
52    Time cur_time, diff, period = timeSyncPeriod();
53
54    do {
55        cur_time.setTimer();
56        diff = cur_time - lastTime;
57        Time remainder = period - diff;
58        if (diff < period && remainder > _spinThreshold) {
59            DPRINTF(TimeSync, "Sleeping to sync with real time.\n");
60            // Sleep until the end of the period, or until a signal.
61            sleep(remainder);
62            // Refresh the current time.
63            cur_time.setTimer();
64        }
65    } while (diff < period);
66    lastTime = cur_time;
67    schedule(&syncEvent, curTick() + _periodTick);
68}
69
70void
71Root::timeSyncEnable(bool en)
72{
73    if (en == _enabled)
74        return;
75    _enabled = en;
76    if (_enabled) {
77        // Get event going.
78        Tick periods = ((curTick() + _periodTick - 1) / _periodTick);
79        Tick nextPeriod = periods * _periodTick;
80        schedule(&syncEvent, nextPeriod);
81    } else {
82        // Stop event.
83        deschedule(&syncEvent);
84    }
85}
86
87/// Configure the period for time sync events.
88void
89Root::timeSyncPeriod(Time newPeriod)
90{
91    bool en = timeSyncEnabled();
92    _period = newPeriod;
93    _periodTick = _period.getTick();
94    timeSyncEnable(en);
95}
96
97/// Set the threshold for time remaining to spin wait.
98void
99Root::timeSyncSpinThreshold(Time newThreshold)
100{
101    bool en = timeSyncEnabled();
102    _spinThreshold = newThreshold;
103    timeSyncEnable(en);
104}
105
106Root::Root(RootParams *p) : SimObject(p), _enabled(false),
107    _periodTick(p->time_sync_period), syncEvent(this)
108{
109    _period.setTick(p->time_sync_period);
110    _spinThreshold.setTick(p->time_sync_spin_threshold);
111
112    assert(_root == NULL);
113    _root = this;
114    lastTime.setTimer();
115
116    simQuantum = p->sim_quantum;
117}
118
119void
120Root::initState()
121{
122    timeSyncEnable(params()->time_sync_enable);
123}
124
125void
126Root::loadState(CheckpointIn &cp)
127{
128    SimObject::loadState(cp);
129    timeSyncEnable(params()->time_sync_enable);
130}
131
132void
133Root::serialize(CheckpointOut &cp) const
134{
135    SERIALIZE_SCALAR(FullSystem);
136    std::string isa = THE_ISA_STR;
137    SERIALIZE_SCALAR(isa);
138}
139
140void
141Root::unserialize(CheckpointIn &cp)
142{}
143
144
145bool FullSystem;
146unsigned int FullSystemInt;
147
148Root *
149RootParams::create()
150{
151    static bool created = false;
152    if (created)
153        panic("only one root object allowed!");
154
155    created = true;
156
157    FullSystem = full_system;
158    FullSystemInt = full_system ? 1 : 0;
159
160    return new Root(this);
161}
162