summaryrefslogtreecommitdiff
path: root/rts/Schedule.h
blob: 23a1a5b770582865c87c32d66508d9649ded8676 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
/* -----------------------------------------------------------------------------
 *
 * (c) The GHC Team 1998-2005
 *
 * Prototypes for functions in Schedule.c
 * (RTS internal scheduler interface)
 *
 * -------------------------------------------------------------------------*/

#pragma once

#include "rts/OSThreads.h"
#include "Capability.h"
#include "Trace.h"

#include "BeginPrivate.h"

/* initScheduler(), exitScheduler()
 * Called from STG :  no
 * Locks assumed   :  none
 */
void initScheduler (void);
void exitScheduler (bool wait_foreign);
void freeScheduler (void);
void markScheduler (evac_fn evac, void *user);

// Place a new thread on the run queue of the current Capability
void scheduleThread (Capability *cap, StgTSO *tso);

// Place a new thread on the run queue of a specified Capability
// (cap is the currently owned Capability, cpu is the number of
// the desired Capability).
void scheduleThreadOn(Capability *cap, StgWord cpu, StgTSO *tso);

/* wakeUpRts()
 *
 * Causes an OS thread to wake up and run the scheduler, if necessary.
 */
#if defined(THREADED_RTS)
void wakeUpRts(void);
#endif

/* raiseExceptionHelper */
StgWord raiseExceptionHelper (StgRegTable *reg, StgTSO *tso, StgClosure *exception);

/* findRetryFrameHelper */
StgWord findRetryFrameHelper (Capability *cap, StgTSO *tso);

/* Entry point for a new worker */
void scheduleWorker (Capability *cap, Task *task);

/* The state of the scheduler.  This is used to control the sequence
 * of events during shutdown.  See Note [shutdown] in Schedule.c.
 */
#define SCHED_RUNNING       0  /* running as normal */
#define SCHED_INTERRUPTING  1  /* before threads are deleted */
#define SCHED_SHUTTING_DOWN 2  /* final shutdown */

extern volatile StgWord sched_state;

/*
 * flag that tracks whether we have done any execution in this time
 * slice, and controls the disabling of the interval timer.
 *
 * The timer interrupt transitions ACTIVITY_YES into
 * ACTIVITY_MAYBE_NO, waits for RtsFlags.GcFlags.idleGCDelayTime,
 * and then:
 *   - if idle GC is no, set ACTIVITY_INACTIVE and wakeUpRts()
 *   - if idle GC is off, set ACTIVITY_DONE_GC and stopTimer()
 *
 * If the scheduler finds ACTIVITY_INACTIVE, then it sets
 * ACTIVITY_DONE_GC, performs the GC and calls stopTimer().
 *
 * If the scheduler finds ACTIVITY_DONE_GC and it has a thread to run,
 * it enables the timer again with startTimer().
 */
#define ACTIVITY_YES      0
  // the RTS is active
#define ACTIVITY_MAYBE_NO 1
  // no activity since the last timer signal
#define ACTIVITY_INACTIVE 2
  // RtsFlags.GcFlags.idleGCDelayTime has passed with no activity
#define ACTIVITY_DONE_GC  3
  // like ACTIVITY_INACTIVE, but we've done a GC too (if idle GC is
  // enabled) and the interval timer is now turned off.

/* Recent activity flag.
 * Locks required  : Transition from MAYBE_NO to INACTIVE
 * happens in the timer signal, so it is atomic.  Trnasition from
 * INACTIVE to DONE_GC happens under sched_mutex.  No lock required
 * to set it to ACTIVITY_YES.
 */
extern volatile StgWord recent_activity;

/* Thread queues.
 * Locks required  : sched_mutex
 */
#if !defined(THREADED_RTS)
extern  StgTSO *blocked_queue_hd, *blocked_queue_tl;
extern  StgTSO *sleeping_queue;
#endif

extern bool heap_overflow;

#if defined(THREADED_RTS)
extern Mutex sched_mutex;
#endif

/* Called by shutdown_handler(). */
void interruptStgRts (void);

void resurrectThreads (StgTSO *);

/* -----------------------------------------------------------------------------
 * Some convenient macros/inline functions...
 */

#if !IN_STG_CODE

/* END_TSO_QUEUE and friends now defined in includes/stg/MiscClosures.h */

/* Add a thread to the end of the run queue.
 * NOTE: tso->link should be END_TSO_QUEUE before calling this macro.
 * ASSUMES: cap->running_task is the current task.
 */
EXTERN_INLINE void
appendToRunQueue (Capability *cap, StgTSO *tso);

EXTERN_INLINE void
appendToRunQueue (Capability *cap, StgTSO *tso)
{
    ASSERT(tso->_link == END_TSO_QUEUE);
    if (cap->run_queue_hd == END_TSO_QUEUE) {
        cap->run_queue_hd = tso;
        tso->block_info.prev = END_TSO_QUEUE;
    } else {
        setTSOLink(cap, cap->run_queue_tl, tso);
        setTSOPrev(cap, tso, cap->run_queue_tl);
    }
    cap->run_queue_tl = tso;
    cap->n_run_queue++;
}

/* Push a thread on the beginning of the run queue.
 * ASSUMES: cap->running_task is the current task.
 */
EXTERN_INLINE void
pushOnRunQueue (Capability *cap, StgTSO *tso);

EXTERN_INLINE void
pushOnRunQueue (Capability *cap, StgTSO *tso)
{
    setTSOLink(cap, tso, cap->run_queue_hd);
    tso->block_info.prev = END_TSO_QUEUE;
    if (cap->run_queue_hd != END_TSO_QUEUE) {
        setTSOPrev(cap, cap->run_queue_hd, tso);
    }
    cap->run_queue_hd = tso;
    if (cap->run_queue_tl == END_TSO_QUEUE) {
        cap->run_queue_tl = tso;
    }
    cap->n_run_queue++;
}

/* Pop the first thread off the runnable queue.
 */
INLINE_HEADER StgTSO *
popRunQueue (Capability *cap)
{
    StgTSO *t = cap->run_queue_hd;
    ASSERT(t != END_TSO_QUEUE);
    cap->run_queue_hd = t->_link;
    if (t->_link != END_TSO_QUEUE) {
        t->_link->block_info.prev = END_TSO_QUEUE;
    }
    t->_link = END_TSO_QUEUE; // no write barrier req'd
    if (cap->run_queue_hd == END_TSO_QUEUE) {
        cap->run_queue_tl = END_TSO_QUEUE;
    }
    cap->n_run_queue--;
    return t;
}

INLINE_HEADER StgTSO *
peekRunQueue (Capability *cap)
{
    return cap->run_queue_hd;
}

void promoteInRunQueue (Capability *cap, StgTSO *tso);

/* Add a thread to the end of the blocked queue.
 */
#if !defined(THREADED_RTS)
INLINE_HEADER void
appendToBlockedQueue(StgTSO *tso)
{
    ASSERT(tso->_link == END_TSO_QUEUE);
    if (blocked_queue_hd == END_TSO_QUEUE) {
        blocked_queue_hd = tso;
    } else {
        setTSOLink(&MainCapability, blocked_queue_tl, tso);
    }
    blocked_queue_tl = tso;
}
#endif

/* Check whether various thread queues are empty
 */
INLINE_HEADER bool
emptyQueue (StgTSO *q)
{
    return (q == END_TSO_QUEUE);
}

INLINE_HEADER bool
emptyRunQueue(Capability *cap)
{
    return cap->n_run_queue == 0;
}

INLINE_HEADER void
truncateRunQueue(Capability *cap)
{
    cap->run_queue_hd = END_TSO_QUEUE;
    cap->run_queue_tl = END_TSO_QUEUE;
    cap->n_run_queue = 0;
}

#if !defined(THREADED_RTS)
#define EMPTY_BLOCKED_QUEUE()  (emptyQueue(blocked_queue_hd))
#define EMPTY_SLEEPING_QUEUE() (emptyQueue(sleeping_queue))
#endif

INLINE_HEADER bool
emptyThreadQueues(Capability *cap)
{
    return emptyRunQueue(cap)
#if !defined(THREADED_RTS)
        && EMPTY_BLOCKED_QUEUE() && EMPTY_SLEEPING_QUEUE()
#endif
    ;
}

#endif /* !IN_STG_CODE */

#include "EndPrivate.h"