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
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
|
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "kmp.h"
#include "kmp_i18n.h"
#include "kmp_io.h"
#include "kmp_str.h"
#if OMPT_SUPPORT
#include "ompt-specific.h"
#endif
/*!
@ingroup CANCELLATION
@param loc_ref location of the original task directive
@param gtid Global thread ID of encountering thread
@param cncl_kind Cancellation kind (parallel, for, sections, taskgroup)
@return returns true if the cancellation request has been activated and the
execution thread needs to proceed to the end of the canceled region.
Request cancellation of the binding OpenMP region.
*/
kmp_int32 __kmpc_cancel(ident_t *loc_ref, kmp_int32 gtid, kmp_int32 cncl_kind) {
kmp_info_t *this_thr = __kmp_threads[gtid];
KC_TRACE(10, ("__kmpc_cancel: T#%d request %d OMP_CANCELLATION=%d\n", gtid,
cncl_kind, __kmp_omp_cancellation));
KMP_DEBUG_ASSERT(cncl_kind != cancel_noreq);
KMP_DEBUG_ASSERT(cncl_kind == cancel_parallel || cncl_kind == cancel_loop ||
cncl_kind == cancel_sections ||
cncl_kind == cancel_taskgroup);
KMP_DEBUG_ASSERT(__kmp_get_gtid() == gtid);
if (__kmp_omp_cancellation) {
switch (cncl_kind) {
case cancel_parallel:
case cancel_loop:
case cancel_sections:
// cancellation requests for parallel and worksharing constructs
// are handled through the team structure
{
kmp_team_t *this_team = this_thr->th.th_team;
KMP_DEBUG_ASSERT(this_team);
kmp_int32 old = cancel_noreq;
this_team->t.t_cancel_request.compare_exchange_strong(old, cncl_kind);
if (old == cancel_noreq || old == cncl_kind) {
// we do not have a cancellation request in this team or we do have
// one that matches the current request -> cancel
#if OMPT_SUPPORT && OMPT_OPTIONAL
if (ompt_enabled.ompt_callback_cancel) {
ompt_data_t *task_data;
__ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL,
NULL);
ompt_cancel_flag_t type = ompt_cancel_parallel;
if (cncl_kind == cancel_parallel)
type = ompt_cancel_parallel;
else if (cncl_kind == cancel_loop)
type = ompt_cancel_loop;
else if (cncl_kind == cancel_sections)
type = ompt_cancel_sections;
ompt_callbacks.ompt_callback(ompt_callback_cancel)(
task_data, type | ompt_cancel_activated,
OMPT_GET_RETURN_ADDRESS(0));
}
#endif // OMPT_SUPPORT && OMPT_OPTIONAL
return 1 /* true */;
}
break;
}
case cancel_taskgroup:
// cancellation requests for a task group
// are handled through the taskgroup structure
{
kmp_taskdata_t *task;
kmp_taskgroup_t *taskgroup;
task = this_thr->th.th_current_task;
KMP_DEBUG_ASSERT(task);
taskgroup = task->td_taskgroup;
if (taskgroup) {
kmp_int32 old = cancel_noreq;
taskgroup->cancel_request.compare_exchange_strong(old, cncl_kind);
if (old == cancel_noreq || old == cncl_kind) {
// we do not have a cancellation request in this taskgroup or we do
// have one that matches the current request -> cancel
#if OMPT_SUPPORT && OMPT_OPTIONAL
if (ompt_enabled.ompt_callback_cancel) {
ompt_data_t *task_data;
__ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL,
NULL);
ompt_callbacks.ompt_callback(ompt_callback_cancel)(
task_data, ompt_cancel_taskgroup | ompt_cancel_activated,
OMPT_GET_RETURN_ADDRESS(0));
}
#endif
return 1 /* true */;
}
} else {
// TODO: what needs to happen here?
// the specification disallows cancellation w/o taskgroups
// so we might do anything here, let's abort for now
KMP_ASSERT(0 /* false */);
}
}
break;
default:
KMP_ASSERT(0 /* false */);
}
}
// ICV OMP_CANCELLATION=false, so we ignored this cancel request
KMP_DEBUG_ASSERT(!__kmp_omp_cancellation);
return 0 /* false */;
}
/*!
@ingroup CANCELLATION
@param loc_ref location of the original task directive
@param gtid Global thread ID of encountering thread
@param cncl_kind Cancellation kind (parallel, for, sections, taskgroup)
@return returns true if a matching cancellation request has been flagged in the
RTL and the encountering thread has to cancel..
Cancellation point for the encountering thread.
*/
kmp_int32 __kmpc_cancellationpoint(ident_t *loc_ref, kmp_int32 gtid,
kmp_int32 cncl_kind) {
kmp_info_t *this_thr = __kmp_threads[gtid];
KC_TRACE(10,
("__kmpc_cancellationpoint: T#%d request %d OMP_CANCELLATION=%d\n",
gtid, cncl_kind, __kmp_omp_cancellation));
KMP_DEBUG_ASSERT(cncl_kind != cancel_noreq);
KMP_DEBUG_ASSERT(cncl_kind == cancel_parallel || cncl_kind == cancel_loop ||
cncl_kind == cancel_sections ||
cncl_kind == cancel_taskgroup);
KMP_DEBUG_ASSERT(__kmp_get_gtid() == gtid);
if (__kmp_omp_cancellation) {
switch (cncl_kind) {
case cancel_parallel:
case cancel_loop:
case cancel_sections:
// cancellation requests for parallel and worksharing constructs
// are handled through the team structure
{
kmp_team_t *this_team = this_thr->th.th_team;
KMP_DEBUG_ASSERT(this_team);
if (this_team->t.t_cancel_request) {
if (cncl_kind == this_team->t.t_cancel_request) {
// the request in the team structure matches the type of
// cancellation point so we can cancel
#if OMPT_SUPPORT && OMPT_OPTIONAL
if (ompt_enabled.ompt_callback_cancel) {
ompt_data_t *task_data;
__ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL,
NULL);
ompt_cancel_flag_t type = ompt_cancel_parallel;
if (cncl_kind == cancel_parallel)
type = ompt_cancel_parallel;
else if (cncl_kind == cancel_loop)
type = ompt_cancel_loop;
else if (cncl_kind == cancel_sections)
type = ompt_cancel_sections;
ompt_callbacks.ompt_callback(ompt_callback_cancel)(
task_data, type | ompt_cancel_detected,
OMPT_GET_RETURN_ADDRESS(0));
}
#endif
return 1 /* true */;
}
KMP_ASSERT(0 /* false */);
} else {
// we do not have a cancellation request pending, so we just
// ignore this cancellation point
return 0;
}
break;
}
case cancel_taskgroup:
// cancellation requests for a task group
// are handled through the taskgroup structure
{
kmp_taskdata_t *task;
kmp_taskgroup_t *taskgroup;
task = this_thr->th.th_current_task;
KMP_DEBUG_ASSERT(task);
taskgroup = task->td_taskgroup;
if (taskgroup) {
// return the current status of cancellation for the taskgroup
#if OMPT_SUPPORT && OMPT_OPTIONAL
if (ompt_enabled.ompt_callback_cancel &&
!!taskgroup->cancel_request) {
ompt_data_t *task_data;
__ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL,
NULL);
ompt_callbacks.ompt_callback(ompt_callback_cancel)(
task_data, ompt_cancel_taskgroup | ompt_cancel_detected,
OMPT_GET_RETURN_ADDRESS(0));
}
#endif
return !!taskgroup->cancel_request;
} else {
// if a cancellation point is encountered by a task that does not
// belong to a taskgroup, it is OK to ignore it
return 0 /* false */;
}
}
default:
KMP_ASSERT(0 /* false */);
}
}
// ICV OMP_CANCELLATION=false, so we ignore the cancellation point
KMP_DEBUG_ASSERT(!__kmp_omp_cancellation);
return 0 /* false */;
}
/*!
@ingroup CANCELLATION
@param loc_ref location of the original task directive
@param gtid Global thread ID of encountering thread
@return returns true if a matching cancellation request has been flagged in the
RTL and the encountering thread has to cancel..
Barrier with cancellation point to send threads from the barrier to the
end of the parallel region. Needs a special code pattern as documented
in the design document for the cancellation feature.
*/
kmp_int32 __kmpc_cancel_barrier(ident_t *loc, kmp_int32 gtid) {
int ret = 0 /* false */;
kmp_info_t *this_thr = __kmp_threads[gtid];
kmp_team_t *this_team = this_thr->th.th_team;
KMP_DEBUG_ASSERT(__kmp_get_gtid() == gtid);
// call into the standard barrier
__kmpc_barrier(loc, gtid);
// if cancellation is active, check cancellation flag
if (__kmp_omp_cancellation) {
// depending on which construct to cancel, check the flag and
// reset the flag
switch (KMP_ATOMIC_LD_RLX(&(this_team->t.t_cancel_request))) {
case cancel_parallel:
ret = 1;
// ensure that threads have checked the flag, when
// leaving the above barrier
__kmpc_barrier(loc, gtid);
this_team->t.t_cancel_request = cancel_noreq;
// the next barrier is the fork/join barrier, which
// synchronizes the threads leaving here
break;
case cancel_loop:
case cancel_sections:
ret = 1;
// ensure that threads have checked the flag, when
// leaving the above barrier
__kmpc_barrier(loc, gtid);
this_team->t.t_cancel_request = cancel_noreq;
// synchronize the threads again to make sure we do not have any run-away
// threads that cause a race on the cancellation flag
__kmpc_barrier(loc, gtid);
break;
case cancel_taskgroup:
// this case should not occur
KMP_ASSERT(0 /* false */);
break;
case cancel_noreq:
// do nothing
break;
default:
KMP_ASSERT(0 /* false */);
}
}
return ret;
}
/*!
@ingroup CANCELLATION
@param loc_ref location of the original task directive
@param gtid Global thread ID of encountering thread
@return returns true if a matching cancellation request has been flagged in the
RTL and the encountering thread has to cancel..
Query function to query the current status of cancellation requests.
Can be used to implement the following pattern:
if (kmp_get_cancellation_status(kmp_cancel_parallel)) {
perform_cleanup();
#pragma omp cancellation point parallel
}
*/
int __kmp_get_cancellation_status(int cancel_kind) {
if (__kmp_omp_cancellation) {
kmp_info_t *this_thr = __kmp_entry_thread();
switch (cancel_kind) {
case cancel_parallel:
case cancel_loop:
case cancel_sections: {
kmp_team_t *this_team = this_thr->th.th_team;
return this_team->t.t_cancel_request == cancel_kind;
}
case cancel_taskgroup: {
kmp_taskdata_t *task;
kmp_taskgroup_t *taskgroup;
task = this_thr->th.th_current_task;
taskgroup = task->td_taskgroup;
return taskgroup && taskgroup->cancel_request;
}
}
}
return 0 /* false */;
}
|