queue.c 6.99 KB
Newer Older
1
/*******************************************************************************
2
 * This file is part of SWIFT.
3
 * Copyright (c) 2012 Pedro Gonnet (pedro.gonnet@durham.ac.uk)
4
 *
5
6
7
8
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
9
 *
10
11
12
13
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
14
 *
15
16
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
17
 *
18
19
20
21
22
23
24
25
26
27
 ******************************************************************************/

/* Config parameters. */
#include "../config.h"

/* Some standard headers. */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

28
29
/* MPI headers. */
#ifdef WITH_MPI
30
#include <mpi.h>
31
32
#endif

33
34
35
/* This object's header. */
#include "queue.h"

36
/* Local headers. */
37
#include "const.h"
38
#include "error.h"
39
40
41

/* Counter macros. */
#ifdef COUNTER
42
#define COUNT(c) (__sync_add_and_fetch(&queue_counter[c], 1))
43
#else
44
#define COUNT(c)
45
46
47
#endif

/* The counters. */
48
int queue_counter[queue_counter_count];
49

Pedro Gonnet's avatar
Pedro Gonnet committed
50
51
52
53
54
55
56
/**
 * @brief Insert a used tasks into the given queue.
 *
 * @param q The #queue.
 * @param t The #task.
 */

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
void queue_insert(struct queue *q, struct task *t) {

  int k, *tid;
  struct task *tasks;

  /* Lock the queue. */
  if (lock_lock(&q->lock) != 0) error("Failed to get queue lock.");

  tid = q->tid;
  tasks = q->tasks;

  /* Does the queue need to be grown? */
  if (q->count == q->size) {
    int *temp;
    q->size *= queue_sizegrow;
    if ((temp = (int *)malloc(sizeof(int) * q->size)) == NULL)
      error("Failed to allocate new indices.");
    memcpy(temp, tid, sizeof(int) * q->count);
    free(tid);
    q->tid = tid = temp;
  }

  /* Drop the task at the end of the queue. */
  tid[q->count] = (t - tasks);
  q->count += 1;

  /* Shuffle up. */
  for (k = q->count - 1; k > 0; k = (k - 1) / 2)
    if (tasks[tid[k]].weight > tasks[tid[(k - 1) / 2]].weight) {
      int temp = tid[k];
      tid[k] = tid[(k - 1) / 2];
      tid[(k - 1) / 2] = temp;
    } else
      break;

  /* Check the queue's consistency. */
  /* for ( k = 1 ; k < q->count ; k++ )
      if ( tasks[ tid[(k-1)/2] ].weight < tasks[ tid[k] ].weight )
          error( "Queue heap is disordered." ); */

  /* Unlock the queue. */
  if (lock_unlock(&q->lock) != 0) error("Failed to unlock queue.");
}
Pedro Gonnet's avatar
Pedro Gonnet committed
100

101
/**
102
103
104
105
106
107
 * @brief Initialize the given queue.
 *
 * @param q The #queue.
 * @param tasks List of tasks to which the queue indices refer to.
 */

108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
void queue_init(struct queue *q, struct task *tasks) {

  /* Allocate the task list if needed. */
  q->size = queue_sizeinit;
  if ((q->tid = (int *)malloc(sizeof(int) * q->size)) == NULL)
    error("Failed to allocate queue tids.");

  /* Set the tasks pointer. */
  q->tasks = tasks;

  /* Init counters. */
  q->count = 0;

  /* Init the queue lock. */
  if (lock_init(&q->lock) != 0) error("Failed to init queue lock.");
}

125
126
127
128
/**
 * @brief Get a task free of dependencies and conflicts.
 *
 * @param q The task #queue.
129
 * @param prev The previous #task extracted from this #queue.
130
131
132
 * @param blocking Block until access to the queue is granted.
 */

133
struct task *queue_gettask(struct queue *q, const struct task *prev, int blocking) {
134
135

  lock_type *qlock = &q->lock;
136
  struct task *res = NULL;
137
138
139
140
141
142
143
144
145
146
147
148

  /* If there are no tasks, leave immediately. */
  if (q->count == 0) return NULL;

  /* Grab the task lock. */
  if (blocking) {
    if (lock_lock(qlock) != 0) error("Locking the qlock failed.\n");
  } else {
    if (lock_trylock(qlock) != 0) return NULL;
  }

  /* Set some pointers we will use often. */
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
  int *qtid = q->tid;
  struct task *qtasks = q->tasks;
  const int qcount = q->count;

  /* Data for the sliding window in which to try the task with the
     best overlap with the previous task. */
  struct {
    int ind, tid;
    float score;
  } window[queue_search_window];
  int window_count = 0;
  int tid = -1;
  int ind = -1;

  /* Loop over the queue entries. */
  for (int k = 0; k < qcount; k++) {
    if (k < queue_search_window) {
      window[window_count].ind = k;
      window[window_count].tid = qtid[k];
      window[window_count].score = task_overlap(prev, &qtasks[qtid[k]]);
      window_count += 1;
    } else {
      /* Find the task with the largest overlap. */
      int ind_max = 0;
      for (int i = 1; i < window_count; i++)
        if (window[i].score > window[ind_max].score) ind_max = i;

      /* Try to lock that task. */
      if (task_lock(&qtasks[window[ind_max].tid])) {
        tid = window[ind_max].tid;
        ind = window[ind_max].ind;
        // message("best task has overlap %f.", window[ind_max].score);
181
182
        break;

183
184
185
186
187
188
189
        /* Otherwise, replace it with a new one from the queue. */
      } else {
        window[ind_max].ind = k;
        window[ind_max].tid = qtid[k];
        window[ind_max].score = task_overlap(prev, &qtasks[qtid[k]]);
      }
    }
190
191
  }

192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
  /* If we didn't get a task, loop through whatever is left in the window. */
  if (tid < 0) {
    while (window_count > 0) {
      int ind_max = 0;
      for (int i = 1; i < window_count; i++)
        if (window[i].score > window[ind_max].score) ind_max = i;
      if (task_lock(&qtasks[window[ind_max].tid])) {
        tid = window[ind_max].tid;
        ind = window[ind_max].ind;
        // message("best task has overlap %f.", window[ind_max].score);
        break;
      } else {
        window_count -= 1;
        window[ind_max] = window[window_count];
      }
    }
208
209
210
  }

  /* Did we get a task? */
211
  if (ind >= 0) {
212
213

    /* Another one bites the dust. */
214
    const int qcount = q->count -= 1;
Pedro Gonnet's avatar
Pedro Gonnet committed
215
216
217
    
    /* Get a pointer on the task that we want to return. */
    res = &qtasks[tid];
218
219

    /* Swap this task with the last task and re-heap. */
220
    int k = ind;
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
    if (k < qcount) {
      qtid[k] = qtid[qcount];
      int w = qtasks[qtid[k]].weight;
      while (k > 0 && w > qtasks[qtid[(k - 1) / 2]].weight) {
        int temp = q->tid[k];
        q->tid[k] = q->tid[(k - 1) / 2];
        q->tid[(k - 1) / 2] = temp;
        k = (k - 1) / 2;
      }
      int i;
      while ((i = 2 * k + 1) < qcount) {
        if (i + 1 < qcount &&
            qtasks[qtid[i + 1]].weight > qtasks[qtid[i]].weight)
          i += 1;
        if (qtasks[qtid[i]].weight > w) {
          int temp = qtid[i];
          qtid[i] = qtid[k];
          qtid[k] = temp;
          k = i;
        } else
          break;
      }
243
244
    }

245
246
247
248
249
250
251
252
253
254
  } else
    res = NULL;

  /* Check the queue's consistency. */
  /* for ( k = 1 ; k < q->count ; k++ )
      if ( qtasks[ qtid[(k-1)/2] ].weight < qtasks[ qtid[k] ].weight )
          error( "Queue heap is disordered." ); */

  /* Release the task lock. */
  if (lock_unlock(qlock) != 0) error("Unlocking the qlock failed.\n");
255

256
257
258
  /* Take the money and run. */
  return res;
}