1 /* 2 * Event loop thread 3 * 4 * Copyright Red Hat Inc., 2013 5 * 6 * Authors: 7 * Stefan Hajnoczi <stefanha@redhat.com> 8 * 9 * This work is licensed under the terms of the GNU GPL, version 2 or later. 10 * See the COPYING file in the top-level directory. 11 * 12 */ 13 14 #include "qemu/osdep.h" 15 #include "qom/object.h" 16 #include "qom/object_interfaces.h" 17 #include "qemu/module.h" 18 #include "block/aio.h" 19 #include "block/block.h" 20 #include "sysemu/iothread.h" 21 #include "qmp-commands.h" 22 #include "qemu/error-report.h" 23 #include "qemu/rcu.h" 24 #include "qemu/main-loop.h" 25 26 typedef ObjectClass IOThreadClass; 27 28 #define IOTHREAD_GET_CLASS(obj) \ 29 OBJECT_GET_CLASS(IOThreadClass, obj, TYPE_IOTHREAD) 30 #define IOTHREAD_CLASS(klass) \ 31 OBJECT_CLASS_CHECK(IOThreadClass, klass, TYPE_IOTHREAD) 32 33 /* Benchmark results from 2016 on NVMe SSD drives show max polling times around 34 * 16-32 microseconds yield IOPS improvements for both iodepth=1 and iodepth=32 35 * workloads. 36 */ 37 #define IOTHREAD_POLL_MAX_NS_DEFAULT 32768ULL 38 39 static __thread IOThread *my_iothread; 40 41 AioContext *qemu_get_current_aio_context(void) 42 { 43 return my_iothread ? my_iothread->ctx : qemu_get_aio_context(); 44 } 45 46 static void *iothread_run(void *opaque) 47 { 48 IOThread *iothread = opaque; 49 50 rcu_register_thread(); 51 52 my_iothread = iothread; 53 qemu_mutex_lock(&iothread->init_done_lock); 54 iothread->thread_id = qemu_get_thread_id(); 55 qemu_cond_signal(&iothread->init_done_cond); 56 qemu_mutex_unlock(&iothread->init_done_lock); 57 58 while (iothread->running) { 59 aio_poll(iothread->ctx, true); 60 61 if (atomic_read(&iothread->worker_context)) { 62 GMainLoop *loop; 63 64 g_main_context_push_thread_default(iothread->worker_context); 65 iothread->main_loop = 66 g_main_loop_new(iothread->worker_context, TRUE); 67 loop = iothread->main_loop; 68 69 g_main_loop_run(iothread->main_loop); 70 iothread->main_loop = NULL; 71 g_main_loop_unref(loop); 72 73 g_main_context_pop_thread_default(iothread->worker_context); 74 } 75 } 76 77 rcu_unregister_thread(); 78 return NULL; 79 } 80 81 /* Runs in iothread_run() thread */ 82 static void iothread_stop_bh(void *opaque) 83 { 84 IOThread *iothread = opaque; 85 86 iothread->running = false; /* stop iothread_run() */ 87 88 if (iothread->main_loop) { 89 g_main_loop_quit(iothread->main_loop); 90 } 91 } 92 93 void iothread_stop(IOThread *iothread) 94 { 95 if (!iothread->ctx || iothread->stopping) { 96 return; 97 } 98 iothread->stopping = true; 99 aio_bh_schedule_oneshot(iothread->ctx, iothread_stop_bh, iothread); 100 qemu_thread_join(&iothread->thread); 101 } 102 103 static int iothread_stop_iter(Object *object, void *opaque) 104 { 105 IOThread *iothread; 106 107 iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD); 108 if (!iothread) { 109 return 0; 110 } 111 iothread_stop(iothread); 112 return 0; 113 } 114 115 static void iothread_instance_init(Object *obj) 116 { 117 IOThread *iothread = IOTHREAD(obj); 118 119 iothread->poll_max_ns = IOTHREAD_POLL_MAX_NS_DEFAULT; 120 } 121 122 static void iothread_instance_finalize(Object *obj) 123 { 124 IOThread *iothread = IOTHREAD(obj); 125 126 iothread_stop(iothread); 127 if (iothread->worker_context) { 128 g_main_context_unref(iothread->worker_context); 129 iothread->worker_context = NULL; 130 } 131 qemu_cond_destroy(&iothread->init_done_cond); 132 qemu_mutex_destroy(&iothread->init_done_lock); 133 if (!iothread->ctx) { 134 return; 135 } 136 aio_context_unref(iothread->ctx); 137 } 138 139 static void iothread_complete(UserCreatable *obj, Error **errp) 140 { 141 Error *local_error = NULL; 142 IOThread *iothread = IOTHREAD(obj); 143 char *name, *thread_name; 144 145 iothread->stopping = false; 146 iothread->running = true; 147 iothread->thread_id = -1; 148 iothread->ctx = aio_context_new(&local_error); 149 if (!iothread->ctx) { 150 error_propagate(errp, local_error); 151 return; 152 } 153 154 aio_context_set_poll_params(iothread->ctx, 155 iothread->poll_max_ns, 156 iothread->poll_grow, 157 iothread->poll_shrink, 158 &local_error); 159 if (local_error) { 160 error_propagate(errp, local_error); 161 aio_context_unref(iothread->ctx); 162 iothread->ctx = NULL; 163 return; 164 } 165 166 qemu_mutex_init(&iothread->init_done_lock); 167 qemu_cond_init(&iothread->init_done_cond); 168 iothread->once = (GOnce) G_ONCE_INIT; 169 170 /* This assumes we are called from a thread with useful CPU affinity for us 171 * to inherit. 172 */ 173 name = object_get_canonical_path_component(OBJECT(obj)); 174 thread_name = g_strdup_printf("IO %s", name); 175 qemu_thread_create(&iothread->thread, thread_name, iothread_run, 176 iothread, QEMU_THREAD_JOINABLE); 177 g_free(thread_name); 178 g_free(name); 179 180 /* Wait for initialization to complete */ 181 qemu_mutex_lock(&iothread->init_done_lock); 182 while (iothread->thread_id == -1) { 183 qemu_cond_wait(&iothread->init_done_cond, 184 &iothread->init_done_lock); 185 } 186 qemu_mutex_unlock(&iothread->init_done_lock); 187 } 188 189 typedef struct { 190 const char *name; 191 ptrdiff_t offset; /* field's byte offset in IOThread struct */ 192 } PollParamInfo; 193 194 static PollParamInfo poll_max_ns_info = { 195 "poll-max-ns", offsetof(IOThread, poll_max_ns), 196 }; 197 static PollParamInfo poll_grow_info = { 198 "poll-grow", offsetof(IOThread, poll_grow), 199 }; 200 static PollParamInfo poll_shrink_info = { 201 "poll-shrink", offsetof(IOThread, poll_shrink), 202 }; 203 204 static void iothread_get_poll_param(Object *obj, Visitor *v, 205 const char *name, void *opaque, Error **errp) 206 { 207 IOThread *iothread = IOTHREAD(obj); 208 PollParamInfo *info = opaque; 209 int64_t *field = (void *)iothread + info->offset; 210 211 visit_type_int64(v, name, field, errp); 212 } 213 214 static void iothread_set_poll_param(Object *obj, Visitor *v, 215 const char *name, void *opaque, Error **errp) 216 { 217 IOThread *iothread = IOTHREAD(obj); 218 PollParamInfo *info = opaque; 219 int64_t *field = (void *)iothread + info->offset; 220 Error *local_err = NULL; 221 int64_t value; 222 223 visit_type_int64(v, name, &value, &local_err); 224 if (local_err) { 225 goto out; 226 } 227 228 if (value < 0) { 229 error_setg(&local_err, "%s value must be in range [0, %"PRId64"]", 230 info->name, INT64_MAX); 231 goto out; 232 } 233 234 *field = value; 235 236 if (iothread->ctx) { 237 aio_context_set_poll_params(iothread->ctx, 238 iothread->poll_max_ns, 239 iothread->poll_grow, 240 iothread->poll_shrink, 241 &local_err); 242 } 243 244 out: 245 error_propagate(errp, local_err); 246 } 247 248 static void iothread_class_init(ObjectClass *klass, void *class_data) 249 { 250 UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass); 251 ucc->complete = iothread_complete; 252 253 object_class_property_add(klass, "poll-max-ns", "int", 254 iothread_get_poll_param, 255 iothread_set_poll_param, 256 NULL, &poll_max_ns_info, &error_abort); 257 object_class_property_add(klass, "poll-grow", "int", 258 iothread_get_poll_param, 259 iothread_set_poll_param, 260 NULL, &poll_grow_info, &error_abort); 261 object_class_property_add(klass, "poll-shrink", "int", 262 iothread_get_poll_param, 263 iothread_set_poll_param, 264 NULL, &poll_shrink_info, &error_abort); 265 } 266 267 static const TypeInfo iothread_info = { 268 .name = TYPE_IOTHREAD, 269 .parent = TYPE_OBJECT, 270 .class_init = iothread_class_init, 271 .instance_size = sizeof(IOThread), 272 .instance_init = iothread_instance_init, 273 .instance_finalize = iothread_instance_finalize, 274 .interfaces = (InterfaceInfo[]) { 275 {TYPE_USER_CREATABLE}, 276 {} 277 }, 278 }; 279 280 static void iothread_register_types(void) 281 { 282 type_register_static(&iothread_info); 283 } 284 285 type_init(iothread_register_types) 286 287 char *iothread_get_id(IOThread *iothread) 288 { 289 return object_get_canonical_path_component(OBJECT(iothread)); 290 } 291 292 AioContext *iothread_get_aio_context(IOThread *iothread) 293 { 294 return iothread->ctx; 295 } 296 297 static int query_one_iothread(Object *object, void *opaque) 298 { 299 IOThreadInfoList ***prev = opaque; 300 IOThreadInfoList *elem; 301 IOThreadInfo *info; 302 IOThread *iothread; 303 304 iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD); 305 if (!iothread) { 306 return 0; 307 } 308 309 info = g_new0(IOThreadInfo, 1); 310 info->id = iothread_get_id(iothread); 311 info->thread_id = iothread->thread_id; 312 info->poll_max_ns = iothread->poll_max_ns; 313 info->poll_grow = iothread->poll_grow; 314 info->poll_shrink = iothread->poll_shrink; 315 316 elem = g_new0(IOThreadInfoList, 1); 317 elem->value = info; 318 elem->next = NULL; 319 320 **prev = elem; 321 *prev = &elem->next; 322 return 0; 323 } 324 325 IOThreadInfoList *qmp_query_iothreads(Error **errp) 326 { 327 IOThreadInfoList *head = NULL; 328 IOThreadInfoList **prev = &head; 329 Object *container = object_get_objects_root(); 330 331 object_child_foreach(container, query_one_iothread, &prev); 332 return head; 333 } 334 335 void iothread_stop_all(void) 336 { 337 Object *container = object_get_objects_root(); 338 BlockDriverState *bs; 339 BdrvNextIterator it; 340 341 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { 342 AioContext *ctx = bdrv_get_aio_context(bs); 343 if (ctx == qemu_get_aio_context()) { 344 continue; 345 } 346 aio_context_acquire(ctx); 347 bdrv_set_aio_context(bs, qemu_get_aio_context()); 348 aio_context_release(ctx); 349 } 350 351 object_child_foreach(container, iothread_stop_iter, NULL); 352 } 353 354 static gpointer iothread_g_main_context_init(gpointer opaque) 355 { 356 AioContext *ctx; 357 IOThread *iothread = opaque; 358 GSource *source; 359 360 iothread->worker_context = g_main_context_new(); 361 362 ctx = iothread_get_aio_context(iothread); 363 source = aio_get_g_source(ctx); 364 g_source_attach(source, iothread->worker_context); 365 g_source_unref(source); 366 367 aio_notify(iothread->ctx); 368 return NULL; 369 } 370 371 GMainContext *iothread_get_g_main_context(IOThread *iothread) 372 { 373 g_once(&iothread->once, iothread_g_main_context_init, iothread); 374 375 return iothread->worker_context; 376 } 377 378 IOThread *iothread_create(const char *id, Error **errp) 379 { 380 Object *obj; 381 382 obj = object_new_with_props(TYPE_IOTHREAD, 383 object_get_internal_root(), 384 id, errp, NULL); 385 386 return IOTHREAD(obj); 387 } 388 389 void iothread_destroy(IOThread *iothread) 390 { 391 object_unparent(OBJECT(iothread)); 392 } 393 394 /* Lookup IOThread by its id. Only finds user-created objects, not internal 395 * iothread_create() objects. */ 396 IOThread *iothread_by_id(const char *id) 397 { 398 return IOTHREAD(object_resolve_path_type(id, TYPE_IOTHREAD, NULL)); 399 } 400