scheduler.hh revision 12953 
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#ifndef __SYSTEMC_CORE_SCHEDULER_HH__
31#define __SYSTEMC_CORE_SCHEDULER_HH__
32
33#include "systemc/core/list.hh"
34#include "systemc/core/process.hh"
35
36namespace sc_gem5
37{
38
39typedef NodeList<Process> ProcessList;
40
41class Scheduler
42{
43  public:
44    Scheduler();
45
46    uint64_t numCycles() { return _numCycles; }
47    Process *current() { return _current; }
48
49    // Run the initialization phase.
50    void initialize();
51
52    // Run delta cycles until time needs to advance.
53    void runCycles();
54
55    // Put a process on the list of processes to be initialized.
56    void init(Process *p) { initList.pushLast(p); }
57
58    // Run the next process, if there is one.
59    void yield();
60
61    // Put a process on the ready list.
62    void
63    ready(Process *p)
64    {
65        // Clump methods together to minimize context switching.
66        if (p->procKind() == ::sc_core::SC_METHOD_PROC_)
67            readyList.pushFirst(p);
68        else
69            readyList.pushLast(p);
70    }
71
72    // Run the given process immediately, preempting whatever may be running.
73    void
74    runNow(Process *p)
75    {
76        // If a process is running, schedule it/us to run again.
77        if (_current)
78            readyList.pushFirst(_current);
79        // Schedule p to run first.
80        readyList.pushFirst(p);
81        yield();
82    }
83
84  private:
85    uint64_t _numCycles;
86
87    Process *_current;
88
89    ProcessList initList;
90    ProcessList readyList;
91
92    void evaluate();
93    void update();
94    void delta();
95};
96
97extern Scheduler scheduler;
98
99} // namespace sc_gem5
100
101#endif // __SYSTEMC_CORE_SCHEDULER_H__
102