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1 /* Copyright (C) 2005-2017 Free Software Foundation, Inc.
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2 Contributed by Richard Henderson <rth@redhat.com>.
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3
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4 This file is part of the GNU Offloading and Multi Processing Library
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5 (libgomp).
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6
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7 Libgomp is free software; you can redistribute it and/or modify it
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8 under the terms of the GNU General Public License as published by
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9 the Free Software Foundation; either version 3, or (at your option)
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10 any later version.
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11
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12 Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
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13 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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14 FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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15 more details.
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16
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17 Under Section 7 of GPL version 3, you are granted additional
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18 permissions described in the GCC Runtime Library Exception, version
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19 3.1, as published by the Free Software Foundation.
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20
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21 You should have received a copy of the GNU General Public License and
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22 a copy of the GCC Runtime Library Exception along with this program;
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23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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24 <http://www.gnu.org/licenses/>. */
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25
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26 /* This file contains routines to manage the work-share queue for a team
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27 of threads. */
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28
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29 #include "libgomp.h"
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30 #include <stddef.h>
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31 #include <stdlib.h>
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32 #include <string.h>
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33
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34
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35 /* Allocate a new work share structure, preferably from current team's
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36 free gomp_work_share cache. */
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37
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38 static struct gomp_work_share *
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39 alloc_work_share (struct gomp_team *team)
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40 {
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41 struct gomp_work_share *ws;
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42 unsigned int i;
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43
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44 /* This is called in a critical section. */
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45 if (team->work_share_list_alloc != NULL)
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46 {
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47 ws = team->work_share_list_alloc;
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48 team->work_share_list_alloc = ws->next_free;
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49 return ws;
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50 }
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51
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52 #ifdef HAVE_SYNC_BUILTINS
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53 ws = team->work_share_list_free;
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54 /* We need atomic read from work_share_list_free,
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55 as free_work_share can be called concurrently. */
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56 __asm ("" : "+r" (ws));
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57
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58 if (ws && ws->next_free)
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59 {
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60 struct gomp_work_share *next = ws->next_free;
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61 ws->next_free = NULL;
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62 team->work_share_list_alloc = next->next_free;
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63 return next;
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64 }
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65 #else
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66 gomp_mutex_lock (&team->work_share_list_free_lock);
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67 ws = team->work_share_list_free;
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68 if (ws)
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69 {
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70 team->work_share_list_alloc = ws->next_free;
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71 team->work_share_list_free = NULL;
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72 gomp_mutex_unlock (&team->work_share_list_free_lock);
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73 return ws;
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74 }
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75 gomp_mutex_unlock (&team->work_share_list_free_lock);
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76 #endif
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77
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78 team->work_share_chunk *= 2;
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79 ws = gomp_malloc (team->work_share_chunk * sizeof (struct gomp_work_share));
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80 ws->next_alloc = team->work_shares[0].next_alloc;
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81 team->work_shares[0].next_alloc = ws;
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82 team->work_share_list_alloc = &ws[1];
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83 for (i = 1; i < team->work_share_chunk - 1; i++)
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84 ws[i].next_free = &ws[i + 1];
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85 ws[i].next_free = NULL;
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86 return ws;
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87 }
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88
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89 /* Initialize an already allocated struct gomp_work_share.
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90 This shouldn't touch the next_alloc field. */
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91
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92 void
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93 gomp_init_work_share (struct gomp_work_share *ws, bool ordered,
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94 unsigned nthreads)
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95 {
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96 gomp_mutex_init (&ws->lock);
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97 if (__builtin_expect (ordered, 0))
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98 {
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99 #define INLINE_ORDERED_TEAM_IDS_CNT \
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100 ((sizeof (struct gomp_work_share) \
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101 - offsetof (struct gomp_work_share, inline_ordered_team_ids)) \
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102 / sizeof (((struct gomp_work_share *) 0)->inline_ordered_team_ids[0]))
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103
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104 if (nthreads > INLINE_ORDERED_TEAM_IDS_CNT)
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105 ws->ordered_team_ids
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106 = gomp_malloc (nthreads * sizeof (*ws->ordered_team_ids));
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107 else
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108 ws->ordered_team_ids = ws->inline_ordered_team_ids;
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109 memset (ws->ordered_team_ids, '\0',
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110 nthreads * sizeof (*ws->ordered_team_ids));
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111 ws->ordered_num_used = 0;
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112 ws->ordered_owner = -1;
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113 ws->ordered_cur = 0;
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114 }
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115 else
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116 ws->ordered_team_ids = NULL;
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117 gomp_ptrlock_init (&ws->next_ws, NULL);
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118 ws->threads_completed = 0;
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119 }
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120
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121 /* Do any needed destruction of gomp_work_share fields before it
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122 is put back into free gomp_work_share cache or freed. */
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123
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124 void
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125 gomp_fini_work_share (struct gomp_work_share *ws)
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126 {
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127 gomp_mutex_destroy (&ws->lock);
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128 if (ws->ordered_team_ids != ws->inline_ordered_team_ids)
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129 free (ws->ordered_team_ids);
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130 gomp_ptrlock_destroy (&ws->next_ws);
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131 }
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132
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133 /* Free a work share struct, if not orphaned, put it into current
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134 team's free gomp_work_share cache. */
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135
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136 static inline void
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137 free_work_share (struct gomp_team *team, struct gomp_work_share *ws)
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138 {
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139 gomp_fini_work_share (ws);
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140 if (__builtin_expect (team == NULL, 0))
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141 free (ws);
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142 else
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143 {
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144 struct gomp_work_share *next_ws;
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145 #ifdef HAVE_SYNC_BUILTINS
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146 do
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147 {
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148 next_ws = team->work_share_list_free;
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149 ws->next_free = next_ws;
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150 }
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151 while (!__sync_bool_compare_and_swap (&team->work_share_list_free,
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152 next_ws, ws));
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153 #else
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154 gomp_mutex_lock (&team->work_share_list_free_lock);
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155 next_ws = team->work_share_list_free;
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156 ws->next_free = next_ws;
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157 team->work_share_list_free = ws;
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158 gomp_mutex_unlock (&team->work_share_list_free_lock);
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159 #endif
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160 }
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161 }
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162
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163 /* The current thread is ready to begin the next work sharing construct.
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164 In all cases, thr->ts.work_share is updated to point to the new
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165 structure. In all cases the work_share lock is locked. Return true
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166 if this was the first thread to reach this point. */
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167
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168 bool
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169 gomp_work_share_start (bool ordered)
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170 {
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171 struct gomp_thread *thr = gomp_thread ();
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172 struct gomp_team *team = thr->ts.team;
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173 struct gomp_work_share *ws;
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174
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175 /* Work sharing constructs can be orphaned. */
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176 if (team == NULL)
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177 {
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178 ws = gomp_malloc (sizeof (*ws));
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179 gomp_init_work_share (ws, ordered, 1);
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180 thr->ts.work_share = ws;
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181 return ws;
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182 }
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183
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184 ws = thr->ts.work_share;
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185 thr->ts.last_work_share = ws;
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186 ws = gomp_ptrlock_get (&ws->next_ws);
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187 if (ws == NULL)
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188 {
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189 /* This thread encountered a new ws first. */
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190 struct gomp_work_share *ws = alloc_work_share (team);
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191 gomp_init_work_share (ws, ordered, team->nthreads);
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192 thr->ts.work_share = ws;
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193 return true;
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194 }
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195 else
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196 {
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197 thr->ts.work_share = ws;
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198 return false;
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199 }
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200 }
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201
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202 /* The current thread is done with its current work sharing construct.
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203 This version does imply a barrier at the end of the work-share. */
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204
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205 void
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206 gomp_work_share_end (void)
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207 {
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208 struct gomp_thread *thr = gomp_thread ();
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209 struct gomp_team *team = thr->ts.team;
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210 gomp_barrier_state_t bstate;
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211
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212 /* Work sharing constructs can be orphaned. */
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213 if (team == NULL)
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214 {
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215 free_work_share (NULL, thr->ts.work_share);
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216 thr->ts.work_share = NULL;
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217 return;
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218 }
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219
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220 bstate = gomp_barrier_wait_start (&team->barrier);
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221
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222 if (gomp_barrier_last_thread (bstate))
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223 {
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224 if (__builtin_expect (thr->ts.last_work_share != NULL, 1))
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111
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225 {
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226 team->work_shares_to_free = thr->ts.work_share;
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227 free_work_share (team, thr->ts.last_work_share);
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228 }
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229 }
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230
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231 gomp_team_barrier_wait_end (&team->barrier, bstate);
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232 thr->ts.last_work_share = NULL;
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233 }
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234
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235 /* The current thread is done with its current work sharing construct.
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236 This version implies a cancellable barrier at the end of the work-share. */
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237
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238 bool
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239 gomp_work_share_end_cancel (void)
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240 {
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241 struct gomp_thread *thr = gomp_thread ();
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242 struct gomp_team *team = thr->ts.team;
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243 gomp_barrier_state_t bstate;
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244
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245 /* Cancellable work sharing constructs cannot be orphaned. */
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246 bstate = gomp_barrier_wait_cancel_start (&team->barrier);
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247
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248 if (gomp_barrier_last_thread (bstate))
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249 {
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250 if (__builtin_expect (thr->ts.last_work_share != NULL, 1))
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251 {
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252 team->work_shares_to_free = thr->ts.work_share;
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253 free_work_share (team, thr->ts.last_work_share);
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254 }
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255 }
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256 thr->ts.last_work_share = NULL;
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257
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258 return gomp_team_barrier_wait_cancel_end (&team->barrier, bstate);
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259 }
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260
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261 /* The current thread is done with its current work sharing construct.
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262 This version does NOT imply a barrier at the end of the work-share. */
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263
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264 void
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265 gomp_work_share_end_nowait (void)
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266 {
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267 struct gomp_thread *thr = gomp_thread ();
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268 struct gomp_team *team = thr->ts.team;
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269 struct gomp_work_share *ws = thr->ts.work_share;
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270 unsigned completed;
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271
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272 /* Work sharing constructs can be orphaned. */
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273 if (team == NULL)
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274 {
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275 free_work_share (NULL, ws);
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276 thr->ts.work_share = NULL;
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277 return;
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278 }
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279
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280 if (__builtin_expect (thr->ts.last_work_share == NULL, 0))
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281 return;
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282
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283 #ifdef HAVE_SYNC_BUILTINS
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284 completed = __sync_add_and_fetch (&ws->threads_completed, 1);
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285 #else
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286 gomp_mutex_lock (&ws->lock);
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287 completed = ++ws->threads_completed;
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288 gomp_mutex_unlock (&ws->lock);
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289 #endif
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290
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291 if (completed == team->nthreads)
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111
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292 {
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293 team->work_shares_to_free = thr->ts.work_share;
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294 free_work_share (team, thr->ts.last_work_share);
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295 }
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296 thr->ts.last_work_share = NULL;
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297 }
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