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Commit | Line | Data |
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be8d8537 SH |
1 | /* |
2 | * Event loop thread | |
3 | * | |
c3033fd3 | 4 | * Copyright Red Hat Inc., 2013, 2020 |
be8d8537 SH |
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 | ||
d38ea87a | 14 | #include "qemu/osdep.h" |
be8d8537 SH |
15 | #include "qom/object.h" |
16 | #include "qom/object_interfaces.h" | |
17 | #include "qemu/module.h" | |
be8d8537 | 18 | #include "block/aio.h" |
d16341fa | 19 | #include "block/block.h" |
7d5983e3 | 20 | #include "sysemu/event-loop-base.h" |
be8d8537 | 21 | #include "sysemu/iothread.h" |
e688df6b | 22 | #include "qapi/error.h" |
112ed241 | 23 | #include "qapi/qapi-commands-misc.h" |
2f78e491 | 24 | #include "qemu/error-report.h" |
ab28bd23 | 25 | #include "qemu/rcu.h" |
e4370165 | 26 | #include "qemu/main-loop.h" |
be8d8537 | 27 | |
be8d8537 | 28 | |
90c558be | 29 | #ifdef CONFIG_POSIX |
cdd7abfd SH |
30 | /* Benchmark results from 2016 on NVMe SSD drives show max polling times around |
31 | * 16-32 microseconds yield IOPS improvements for both iodepth=1 and iodepth=32 | |
32 | * workloads. | |
33 | */ | |
34 | #define IOTHREAD_POLL_MAX_NS_DEFAULT 32768ULL | |
90c558be PX |
35 | #else |
36 | #define IOTHREAD_POLL_MAX_NS_DEFAULT 0ULL | |
37 | #endif | |
cdd7abfd | 38 | |
be8d8537 SH |
39 | static void *iothread_run(void *opaque) |
40 | { | |
41 | IOThread *iothread = opaque; | |
42 | ||
ab28bd23 | 43 | rcu_register_thread(); |
b60ec76a PX |
44 | /* |
45 | * g_main_context_push_thread_default() must be called before anything | |
46 | * in this new thread uses glib. | |
47 | */ | |
48 | g_main_context_push_thread_default(iothread->worker_context); | |
5f50be9b | 49 | qemu_set_current_aio_context(iothread->ctx); |
88eb7c29 | 50 | iothread->thread_id = qemu_get_thread_id(); |
21c4d15b | 51 | qemu_sem_post(&iothread->init_done_sem); |
88eb7c29 | 52 | |
2362a28e | 53 | while (iothread->running) { |
6ca20620 PX |
54 | /* |
55 | * Note: from functional-wise the g_main_loop_run() below can | |
56 | * already cover the aio_poll() events, but we can't run the | |
57 | * main loop unconditionally because explicit aio_poll() here | |
58 | * is faster than g_main_loop_run() when we do not need the | |
59 | * gcontext at all (e.g., pure block layer iothreads). In | |
60 | * other words, when we want to run the gcontext with the | |
61 | * iothread we need to pay some performance for functionality. | |
62 | */ | |
65c1b5b6 | 63 | aio_poll(iothread->ctx, true); |
329163cb | 64 | |
6c95363d PX |
65 | /* |
66 | * We must check the running state again in case it was | |
67 | * changed in previous aio_poll() | |
68 | */ | |
d73415a3 | 69 | if (iothread->running && qatomic_read(&iothread->run_gcontext)) { |
329163cb | 70 | g_main_loop_run(iothread->main_loop); |
329163cb | 71 | } |
be8d8537 | 72 | } |
ab28bd23 | 73 | |
b60ec76a | 74 | g_main_context_pop_thread_default(iothread->worker_context); |
ab28bd23 | 75 | rcu_unregister_thread(); |
be8d8537 SH |
76 | return NULL; |
77 | } | |
78 | ||
2362a28e SH |
79 | /* Runs in iothread_run() thread */ |
80 | static void iothread_stop_bh(void *opaque) | |
81 | { | |
82 | IOThread *iothread = opaque; | |
83 | ||
84 | iothread->running = false; /* stop iothread_run() */ | |
85 | ||
86 | if (iothread->main_loop) { | |
87 | g_main_loop_quit(iothread->main_loop); | |
88 | } | |
89 | } | |
90 | ||
82d90705 | 91 | void iothread_stop(IOThread *iothread) |
be8d8537 | 92 | { |
82d90705 PX |
93 | if (!iothread->ctx || iothread->stopping) { |
94 | return; | |
2f78e491 | 95 | } |
be8d8537 | 96 | iothread->stopping = true; |
2362a28e | 97 | aio_bh_schedule_oneshot(iothread->ctx, iothread_stop_bh, iothread); |
be8d8537 | 98 | qemu_thread_join(&iothread->thread); |
82d90705 PX |
99 | } |
100 | ||
cdd7abfd SH |
101 | static void iothread_instance_init(Object *obj) |
102 | { | |
103 | IOThread *iothread = IOTHREAD(obj); | |
104 | ||
105 | iothread->poll_max_ns = IOTHREAD_POLL_MAX_NS_DEFAULT; | |
14a2d118 | 106 | iothread->thread_id = -1; |
21c4d15b | 107 | qemu_sem_init(&iothread->init_done_sem, 0); |
b506e0f1 | 108 | /* By default, we don't run gcontext */ |
d73415a3 | 109 | qatomic_set(&iothread->run_gcontext, 0); |
cdd7abfd SH |
110 | } |
111 | ||
dce8921b FZ |
112 | static void iothread_instance_finalize(Object *obj) |
113 | { | |
114 | IOThread *iothread = IOTHREAD(obj); | |
115 | ||
82d90705 | 116 | iothread_stop(iothread); |
14a2d118 | 117 | |
15544349 PX |
118 | /* |
119 | * Before glib2 2.33.10, there is a glib2 bug that GSource context | |
120 | * pointer may not be cleared even if the context has already been | |
121 | * destroyed (while it should). Here let's free the AIO context | |
122 | * earlier to bypass that glib bug. | |
123 | * | |
124 | * We can remove this comment after the minimum supported glib2 | |
125 | * version boosts to 2.33.10. Before that, let's free the | |
126 | * GSources first before destroying any GMainContext. | |
127 | */ | |
128 | if (iothread->ctx) { | |
129 | aio_context_unref(iothread->ctx); | |
130 | iothread->ctx = NULL; | |
131 | } | |
5b3ac23f PX |
132 | if (iothread->worker_context) { |
133 | g_main_context_unref(iothread->worker_context); | |
134 | iothread->worker_context = NULL; | |
0bd2d233 PX |
135 | g_main_loop_unref(iothread->main_loop); |
136 | iothread->main_loop = NULL; | |
5b3ac23f | 137 | } |
21c4d15b | 138 | qemu_sem_destroy(&iothread->init_done_sem); |
be8d8537 SH |
139 | } |
140 | ||
1f14c914 | 141 | static void iothread_init_gcontext(IOThread *iothread, const char *thread_name) |
b506e0f1 PX |
142 | { |
143 | GSource *source; | |
1f14c914 | 144 | g_autofree char *name = g_strdup_printf("%s aio-context", thread_name); |
b506e0f1 PX |
145 | |
146 | iothread->worker_context = g_main_context_new(); | |
147 | source = aio_get_g_source(iothread_get_aio_context(iothread)); | |
1f14c914 | 148 | g_source_set_name(source, name); |
b506e0f1 PX |
149 | g_source_attach(source, iothread->worker_context); |
150 | g_source_unref(source); | |
0bd2d233 | 151 | iothread->main_loop = g_main_loop_new(iothread->worker_context, TRUE); |
b506e0f1 PX |
152 | } |
153 | ||
7d5983e3 | 154 | static void iothread_set_aio_context_params(EventLoopBase *base, Error **errp) |
1793ad02 SG |
155 | { |
156 | ERRP_GUARD(); | |
05e385d2 | 157 | IOThread *iothread = IOTHREAD(base); |
1793ad02 | 158 | |
7d5983e3 NSJ |
159 | if (!iothread->ctx) { |
160 | return; | |
161 | } | |
162 | ||
1793ad02 SG |
163 | aio_context_set_poll_params(iothread->ctx, |
164 | iothread->poll_max_ns, | |
165 | iothread->poll_grow, | |
166 | iothread->poll_shrink, | |
167 | errp); | |
168 | if (*errp) { | |
169 | return; | |
170 | } | |
171 | ||
172 | aio_context_set_aio_params(iothread->ctx, | |
7d5983e3 | 173 | iothread->parent_obj.aio_max_batch, |
1793ad02 | 174 | errp); |
71ad4713 NSJ |
175 | |
176 | aio_context_set_thread_pool_params(iothread->ctx, base->thread_pool_min, | |
177 | base->thread_pool_max, errp); | |
1793ad02 SG |
178 | } |
179 | ||
7d5983e3 NSJ |
180 | |
181 | static void iothread_init(EventLoopBase *base, Error **errp) | |
be8d8537 | 182 | { |
2f78e491 | 183 | Error *local_error = NULL; |
7d5983e3 | 184 | IOThread *iothread = IOTHREAD(base); |
1f14c914 | 185 | g_autofree char *thread_name = NULL; |
be8d8537 SH |
186 | |
187 | iothread->stopping = false; | |
2362a28e | 188 | iothread->running = true; |
668f62ec | 189 | iothread->ctx = aio_context_new(errp); |
2f78e491 | 190 | if (!iothread->ctx) { |
2f78e491 CN |
191 | return; |
192 | } | |
88eb7c29 | 193 | |
1f14c914 FR |
194 | thread_name = g_strdup_printf("IO %s", |
195 | object_get_canonical_path_component(OBJECT(base))); | |
196 | ||
b506e0f1 PX |
197 | /* |
198 | * Init one GMainContext for the iothread unconditionally, even if | |
199 | * it's not used | |
200 | */ | |
1f14c914 | 201 | iothread_init_gcontext(iothread, thread_name); |
b506e0f1 | 202 | |
7d5983e3 | 203 | iothread_set_aio_context_params(base, &local_error); |
0d9d86fb SH |
204 | if (local_error) { |
205 | error_propagate(errp, local_error); | |
206 | aio_context_unref(iothread->ctx); | |
207 | iothread->ctx = NULL; | |
208 | return; | |
209 | } | |
210 | ||
be8d8537 SH |
211 | /* This assumes we are called from a thread with useful CPU affinity for us |
212 | * to inherit. | |
213 | */ | |
d21e8776 | 214 | qemu_thread_create(&iothread->thread, thread_name, iothread_run, |
be8d8537 | 215 | iothread, QEMU_THREAD_JOINABLE); |
88eb7c29 SH |
216 | |
217 | /* Wait for initialization to complete */ | |
88eb7c29 | 218 | while (iothread->thread_id == -1) { |
21c4d15b | 219 | qemu_sem_wait(&iothread->init_done_sem); |
88eb7c29 | 220 | } |
be8d8537 SH |
221 | } |
222 | ||
5e5db499 SH |
223 | typedef struct { |
224 | const char *name; | |
225 | ptrdiff_t offset; /* field's byte offset in IOThread struct */ | |
f0ed36a6 | 226 | } IOThreadParamInfo; |
5e5db499 | 227 | |
f0ed36a6 | 228 | static IOThreadParamInfo poll_max_ns_info = { |
5e5db499 SH |
229 | "poll-max-ns", offsetof(IOThread, poll_max_ns), |
230 | }; | |
f0ed36a6 | 231 | static IOThreadParamInfo poll_grow_info = { |
5e5db499 SH |
232 | "poll-grow", offsetof(IOThread, poll_grow), |
233 | }; | |
f0ed36a6 | 234 | static IOThreadParamInfo poll_shrink_info = { |
5e5db499 SH |
235 | "poll-shrink", offsetof(IOThread, poll_shrink), |
236 | }; | |
237 | ||
0445409d | 238 | static void iothread_get_param(Object *obj, Visitor *v, |
1cc7eada | 239 | const char *name, IOThreadParamInfo *info, Error **errp) |
0d9d86fb SH |
240 | { |
241 | IOThread *iothread = IOTHREAD(obj); | |
5e5db499 | 242 | int64_t *field = (void *)iothread + info->offset; |
0d9d86fb | 243 | |
5e5db499 | 244 | visit_type_int64(v, name, field, errp); |
0d9d86fb SH |
245 | } |
246 | ||
0445409d | 247 | static bool iothread_set_param(Object *obj, Visitor *v, |
1cc7eada | 248 | const char *name, IOThreadParamInfo *info, Error **errp) |
0d9d86fb SH |
249 | { |
250 | IOThread *iothread = IOTHREAD(obj); | |
5e5db499 | 251 | int64_t *field = (void *)iothread + info->offset; |
0d9d86fb SH |
252 | int64_t value; |
253 | ||
668f62ec | 254 | if (!visit_type_int64(v, name, &value, errp)) { |
0445409d | 255 | return false; |
0d9d86fb SH |
256 | } |
257 | ||
258 | if (value < 0) { | |
dcfe4805 | 259 | error_setg(errp, "%s value must be in range [0, %" PRId64 "]", |
5e5db499 | 260 | info->name, INT64_MAX); |
0445409d | 261 | return false; |
0d9d86fb SH |
262 | } |
263 | ||
5e5db499 | 264 | *field = value; |
0d9d86fb | 265 | |
0445409d SG |
266 | return true; |
267 | } | |
268 | ||
269 | static void iothread_get_poll_param(Object *obj, Visitor *v, | |
270 | const char *name, void *opaque, Error **errp) | |
271 | { | |
1cc7eada | 272 | IOThreadParamInfo *info = opaque; |
0445409d | 273 | |
1cc7eada | 274 | iothread_get_param(obj, v, name, info, errp); |
0445409d SG |
275 | } |
276 | ||
277 | static void iothread_set_poll_param(Object *obj, Visitor *v, | |
278 | const char *name, void *opaque, Error **errp) | |
279 | { | |
280 | IOThread *iothread = IOTHREAD(obj); | |
1cc7eada | 281 | IOThreadParamInfo *info = opaque; |
0445409d | 282 | |
1cc7eada | 283 | if (!iothread_set_param(obj, v, name, info, errp)) { |
0445409d SG |
284 | return; |
285 | } | |
286 | ||
0d9d86fb | 287 | if (iothread->ctx) { |
5e5db499 SH |
288 | aio_context_set_poll_params(iothread->ctx, |
289 | iothread->poll_max_ns, | |
290 | iothread->poll_grow, | |
291 | iothread->poll_shrink, | |
dcfe4805 | 292 | errp); |
0d9d86fb | 293 | } |
0d9d86fb SH |
294 | } |
295 | ||
be8d8537 SH |
296 | static void iothread_class_init(ObjectClass *klass, void *class_data) |
297 | { | |
7d5983e3 NSJ |
298 | EventLoopBaseClass *bc = EVENT_LOOP_BASE_CLASS(klass); |
299 | ||
300 | bc->init = iothread_init; | |
301 | bc->update_params = iothread_set_aio_context_params; | |
0d9d86fb SH |
302 | |
303 | object_class_property_add(klass, "poll-max-ns", "int", | |
5e5db499 SH |
304 | iothread_get_poll_param, |
305 | iothread_set_poll_param, | |
d2623129 | 306 | NULL, &poll_max_ns_info); |
5e5db499 SH |
307 | object_class_property_add(klass, "poll-grow", "int", |
308 | iothread_get_poll_param, | |
309 | iothread_set_poll_param, | |
d2623129 | 310 | NULL, &poll_grow_info); |
5e5db499 SH |
311 | object_class_property_add(klass, "poll-shrink", "int", |
312 | iothread_get_poll_param, | |
313 | iothread_set_poll_param, | |
d2623129 | 314 | NULL, &poll_shrink_info); |
be8d8537 SH |
315 | } |
316 | ||
317 | static const TypeInfo iothread_info = { | |
318 | .name = TYPE_IOTHREAD, | |
7d5983e3 | 319 | .parent = TYPE_EVENT_LOOP_BASE, |
be8d8537 SH |
320 | .class_init = iothread_class_init, |
321 | .instance_size = sizeof(IOThread), | |
cdd7abfd | 322 | .instance_init = iothread_instance_init, |
be8d8537 | 323 | .instance_finalize = iothread_instance_finalize, |
be8d8537 SH |
324 | }; |
325 | ||
326 | static void iothread_register_types(void) | |
327 | { | |
328 | type_register_static(&iothread_info); | |
329 | } | |
330 | ||
331 | type_init(iothread_register_types) | |
332 | ||
be8d8537 SH |
333 | char *iothread_get_id(IOThread *iothread) |
334 | { | |
7a309cc9 | 335 | return g_strdup(object_get_canonical_path_component(OBJECT(iothread))); |
be8d8537 SH |
336 | } |
337 | ||
338 | AioContext *iothread_get_aio_context(IOThread *iothread) | |
339 | { | |
340 | return iothread->ctx; | |
341 | } | |
dc3dd0d2 SH |
342 | |
343 | static int query_one_iothread(Object *object, void *opaque) | |
344 | { | |
c3033fd3 | 345 | IOThreadInfoList ***tail = opaque; |
dc3dd0d2 SH |
346 | IOThreadInfo *info; |
347 | IOThread *iothread; | |
348 | ||
349 | iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD); | |
350 | if (!iothread) { | |
351 | return 0; | |
352 | } | |
353 | ||
354 | info = g_new0(IOThreadInfo, 1); | |
355 | info->id = iothread_get_id(iothread); | |
356 | info->thread_id = iothread->thread_id; | |
5fc00480 PH |
357 | info->poll_max_ns = iothread->poll_max_ns; |
358 | info->poll_grow = iothread->poll_grow; | |
359 | info->poll_shrink = iothread->poll_shrink; | |
7d5983e3 | 360 | info->aio_max_batch = iothread->parent_obj.aio_max_batch; |
dc3dd0d2 | 361 | |
c3033fd3 | 362 | QAPI_LIST_APPEND(*tail, info); |
dc3dd0d2 SH |
363 | return 0; |
364 | } | |
365 | ||
366 | IOThreadInfoList *qmp_query_iothreads(Error **errp) | |
367 | { | |
368 | IOThreadInfoList *head = NULL; | |
369 | IOThreadInfoList **prev = &head; | |
bc2256c4 | 370 | Object *container = object_get_objects_root(); |
dc3dd0d2 SH |
371 | |
372 | object_child_foreach(container, query_one_iothread, &prev); | |
373 | return head; | |
374 | } | |
dce8921b | 375 | |
329163cb WY |
376 | GMainContext *iothread_get_g_main_context(IOThread *iothread) |
377 | { | |
d73415a3 | 378 | qatomic_set(&iothread->run_gcontext, 1); |
b506e0f1 | 379 | aio_notify(iothread->ctx); |
329163cb WY |
380 | return iothread->worker_context; |
381 | } | |
0173e21b PX |
382 | |
383 | IOThread *iothread_create(const char *id, Error **errp) | |
384 | { | |
385 | Object *obj; | |
386 | ||
387 | obj = object_new_with_props(TYPE_IOTHREAD, | |
388 | object_get_internal_root(), | |
389 | id, errp, NULL); | |
390 | ||
391 | return IOTHREAD(obj); | |
392 | } | |
393 | ||
394 | void iothread_destroy(IOThread *iothread) | |
395 | { | |
396 | object_unparent(OBJECT(iothread)); | |
397 | } | |
fbcc6923 SH |
398 | |
399 | /* Lookup IOThread by its id. Only finds user-created objects, not internal | |
400 | * iothread_create() objects. */ | |
401 | IOThread *iothread_by_id(const char *id) | |
402 | { | |
403 | return IOTHREAD(object_resolve_path_type(id, TYPE_IOTHREAD, NULL)); | |
404 | } | |
ad22c308 EU |
405 | |
406 | bool qemu_in_iothread(void) | |
407 | { | |
408 | return qemu_get_current_aio_context() == qemu_get_aio_context() ? | |
409 | false : true; | |
410 | } |