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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" |
be8d8537 | 20 | #include "sysemu/iothread.h" |
e688df6b | 21 | #include "qapi/error.h" |
112ed241 | 22 | #include "qapi/qapi-commands-misc.h" |
2f78e491 | 23 | #include "qemu/error-report.h" |
ab28bd23 | 24 | #include "qemu/rcu.h" |
e4370165 | 25 | #include "qemu/main-loop.h" |
be8d8537 | 26 | |
be8d8537 | 27 | typedef ObjectClass IOThreadClass; |
be8d8537 | 28 | |
8110fa1d EH |
29 | DECLARE_CLASS_CHECKERS(IOThreadClass, IOTHREAD, |
30 | TYPE_IOTHREAD) | |
be8d8537 | 31 | |
90c558be | 32 | #ifdef CONFIG_POSIX |
cdd7abfd SH |
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 | |
90c558be PX |
38 | #else |
39 | #define IOTHREAD_POLL_MAX_NS_DEFAULT 0ULL | |
40 | #endif | |
cdd7abfd | 41 | |
be8d8537 SH |
42 | static void *iothread_run(void *opaque) |
43 | { | |
44 | IOThread *iothread = opaque; | |
45 | ||
ab28bd23 | 46 | rcu_register_thread(); |
b60ec76a PX |
47 | /* |
48 | * g_main_context_push_thread_default() must be called before anything | |
49 | * in this new thread uses glib. | |
50 | */ | |
51 | g_main_context_push_thread_default(iothread->worker_context); | |
5f50be9b | 52 | qemu_set_current_aio_context(iothread->ctx); |
88eb7c29 | 53 | iothread->thread_id = qemu_get_thread_id(); |
21c4d15b | 54 | qemu_sem_post(&iothread->init_done_sem); |
88eb7c29 | 55 | |
2362a28e | 56 | while (iothread->running) { |
6ca20620 PX |
57 | /* |
58 | * Note: from functional-wise the g_main_loop_run() below can | |
59 | * already cover the aio_poll() events, but we can't run the | |
60 | * main loop unconditionally because explicit aio_poll() here | |
61 | * is faster than g_main_loop_run() when we do not need the | |
62 | * gcontext at all (e.g., pure block layer iothreads). In | |
63 | * other words, when we want to run the gcontext with the | |
64 | * iothread we need to pay some performance for functionality. | |
65 | */ | |
65c1b5b6 | 66 | aio_poll(iothread->ctx, true); |
329163cb | 67 | |
6c95363d PX |
68 | /* |
69 | * We must check the running state again in case it was | |
70 | * changed in previous aio_poll() | |
71 | */ | |
d73415a3 | 72 | if (iothread->running && qatomic_read(&iothread->run_gcontext)) { |
329163cb | 73 | g_main_loop_run(iothread->main_loop); |
329163cb | 74 | } |
be8d8537 | 75 | } |
ab28bd23 | 76 | |
b60ec76a | 77 | g_main_context_pop_thread_default(iothread->worker_context); |
ab28bd23 | 78 | rcu_unregister_thread(); |
be8d8537 SH |
79 | return NULL; |
80 | } | |
81 | ||
2362a28e SH |
82 | /* Runs in iothread_run() thread */ |
83 | static void iothread_stop_bh(void *opaque) | |
84 | { | |
85 | IOThread *iothread = opaque; | |
86 | ||
87 | iothread->running = false; /* stop iothread_run() */ | |
88 | ||
89 | if (iothread->main_loop) { | |
90 | g_main_loop_quit(iothread->main_loop); | |
91 | } | |
92 | } | |
93 | ||
82d90705 | 94 | void iothread_stop(IOThread *iothread) |
be8d8537 | 95 | { |
82d90705 PX |
96 | if (!iothread->ctx || iothread->stopping) { |
97 | return; | |
2f78e491 | 98 | } |
be8d8537 | 99 | iothread->stopping = true; |
2362a28e | 100 | aio_bh_schedule_oneshot(iothread->ctx, iothread_stop_bh, iothread); |
be8d8537 | 101 | qemu_thread_join(&iothread->thread); |
82d90705 PX |
102 | } |
103 | ||
cdd7abfd SH |
104 | static void iothread_instance_init(Object *obj) |
105 | { | |
106 | IOThread *iothread = IOTHREAD(obj); | |
107 | ||
108 | iothread->poll_max_ns = IOTHREAD_POLL_MAX_NS_DEFAULT; | |
14a2d118 | 109 | iothread->thread_id = -1; |
21c4d15b | 110 | qemu_sem_init(&iothread->init_done_sem, 0); |
b506e0f1 | 111 | /* By default, we don't run gcontext */ |
d73415a3 | 112 | qatomic_set(&iothread->run_gcontext, 0); |
cdd7abfd SH |
113 | } |
114 | ||
dce8921b FZ |
115 | static void iothread_instance_finalize(Object *obj) |
116 | { | |
117 | IOThread *iothread = IOTHREAD(obj); | |
118 | ||
82d90705 | 119 | iothread_stop(iothread); |
14a2d118 | 120 | |
15544349 PX |
121 | /* |
122 | * Before glib2 2.33.10, there is a glib2 bug that GSource context | |
123 | * pointer may not be cleared even if the context has already been | |
124 | * destroyed (while it should). Here let's free the AIO context | |
125 | * earlier to bypass that glib bug. | |
126 | * | |
127 | * We can remove this comment after the minimum supported glib2 | |
128 | * version boosts to 2.33.10. Before that, let's free the | |
129 | * GSources first before destroying any GMainContext. | |
130 | */ | |
131 | if (iothread->ctx) { | |
132 | aio_context_unref(iothread->ctx); | |
133 | iothread->ctx = NULL; | |
134 | } | |
5b3ac23f PX |
135 | if (iothread->worker_context) { |
136 | g_main_context_unref(iothread->worker_context); | |
137 | iothread->worker_context = NULL; | |
0bd2d233 PX |
138 | g_main_loop_unref(iothread->main_loop); |
139 | iothread->main_loop = NULL; | |
5b3ac23f | 140 | } |
21c4d15b | 141 | qemu_sem_destroy(&iothread->init_done_sem); |
be8d8537 SH |
142 | } |
143 | ||
b506e0f1 PX |
144 | static void iothread_init_gcontext(IOThread *iothread) |
145 | { | |
146 | GSource *source; | |
147 | ||
148 | iothread->worker_context = g_main_context_new(); | |
149 | source = aio_get_g_source(iothread_get_aio_context(iothread)); | |
150 | g_source_attach(source, iothread->worker_context); | |
151 | g_source_unref(source); | |
0bd2d233 | 152 | iothread->main_loop = g_main_loop_new(iothread->worker_context, TRUE); |
b506e0f1 PX |
153 | } |
154 | ||
be8d8537 SH |
155 | static void iothread_complete(UserCreatable *obj, Error **errp) |
156 | { | |
2f78e491 | 157 | Error *local_error = NULL; |
be8d8537 | 158 | IOThread *iothread = IOTHREAD(obj); |
7a309cc9 | 159 | char *thread_name; |
be8d8537 SH |
160 | |
161 | iothread->stopping = false; | |
2362a28e | 162 | iothread->running = true; |
668f62ec | 163 | iothread->ctx = aio_context_new(errp); |
2f78e491 | 164 | if (!iothread->ctx) { |
2f78e491 CN |
165 | return; |
166 | } | |
88eb7c29 | 167 | |
b506e0f1 PX |
168 | /* |
169 | * Init one GMainContext for the iothread unconditionally, even if | |
170 | * it's not used | |
171 | */ | |
172 | iothread_init_gcontext(iothread); | |
173 | ||
5e5db499 SH |
174 | aio_context_set_poll_params(iothread->ctx, |
175 | iothread->poll_max_ns, | |
176 | iothread->poll_grow, | |
177 | iothread->poll_shrink, | |
0d9d86fb SH |
178 | &local_error); |
179 | if (local_error) { | |
180 | error_propagate(errp, local_error); | |
181 | aio_context_unref(iothread->ctx); | |
182 | iothread->ctx = NULL; | |
183 | return; | |
184 | } | |
185 | ||
be8d8537 SH |
186 | /* This assumes we are called from a thread with useful CPU affinity for us |
187 | * to inherit. | |
188 | */ | |
7a309cc9 MA |
189 | thread_name = g_strdup_printf("IO %s", |
190 | object_get_canonical_path_component(OBJECT(obj))); | |
d21e8776 | 191 | qemu_thread_create(&iothread->thread, thread_name, iothread_run, |
be8d8537 | 192 | iothread, QEMU_THREAD_JOINABLE); |
d21e8776 | 193 | g_free(thread_name); |
88eb7c29 SH |
194 | |
195 | /* Wait for initialization to complete */ | |
88eb7c29 | 196 | while (iothread->thread_id == -1) { |
21c4d15b | 197 | qemu_sem_wait(&iothread->init_done_sem); |
88eb7c29 | 198 | } |
be8d8537 SH |
199 | } |
200 | ||
5e5db499 SH |
201 | typedef struct { |
202 | const char *name; | |
203 | ptrdiff_t offset; /* field's byte offset in IOThread struct */ | |
204 | } PollParamInfo; | |
205 | ||
206 | static PollParamInfo poll_max_ns_info = { | |
207 | "poll-max-ns", offsetof(IOThread, poll_max_ns), | |
208 | }; | |
209 | static PollParamInfo poll_grow_info = { | |
210 | "poll-grow", offsetof(IOThread, poll_grow), | |
211 | }; | |
212 | static PollParamInfo poll_shrink_info = { | |
213 | "poll-shrink", offsetof(IOThread, poll_shrink), | |
214 | }; | |
215 | ||
216 | static void iothread_get_poll_param(Object *obj, Visitor *v, | |
0d9d86fb SH |
217 | const char *name, void *opaque, Error **errp) |
218 | { | |
219 | IOThread *iothread = IOTHREAD(obj); | |
5e5db499 SH |
220 | PollParamInfo *info = opaque; |
221 | int64_t *field = (void *)iothread + info->offset; | |
0d9d86fb | 222 | |
5e5db499 | 223 | visit_type_int64(v, name, field, errp); |
0d9d86fb SH |
224 | } |
225 | ||
5e5db499 | 226 | static void iothread_set_poll_param(Object *obj, Visitor *v, |
0d9d86fb SH |
227 | const char *name, void *opaque, Error **errp) |
228 | { | |
229 | IOThread *iothread = IOTHREAD(obj); | |
5e5db499 SH |
230 | PollParamInfo *info = opaque; |
231 | int64_t *field = (void *)iothread + info->offset; | |
0d9d86fb SH |
232 | int64_t value; |
233 | ||
668f62ec | 234 | if (!visit_type_int64(v, name, &value, errp)) { |
dcfe4805 | 235 | return; |
0d9d86fb SH |
236 | } |
237 | ||
238 | if (value < 0) { | |
dcfe4805 | 239 | error_setg(errp, "%s value must be in range [0, %" PRId64 "]", |
5e5db499 | 240 | info->name, INT64_MAX); |
dcfe4805 | 241 | return; |
0d9d86fb SH |
242 | } |
243 | ||
5e5db499 | 244 | *field = value; |
0d9d86fb SH |
245 | |
246 | if (iothread->ctx) { | |
5e5db499 SH |
247 | aio_context_set_poll_params(iothread->ctx, |
248 | iothread->poll_max_ns, | |
249 | iothread->poll_grow, | |
250 | iothread->poll_shrink, | |
dcfe4805 | 251 | errp); |
0d9d86fb | 252 | } |
0d9d86fb SH |
253 | } |
254 | ||
be8d8537 SH |
255 | static void iothread_class_init(ObjectClass *klass, void *class_data) |
256 | { | |
257 | UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass); | |
258 | ucc->complete = iothread_complete; | |
0d9d86fb SH |
259 | |
260 | object_class_property_add(klass, "poll-max-ns", "int", | |
5e5db499 SH |
261 | iothread_get_poll_param, |
262 | iothread_set_poll_param, | |
d2623129 | 263 | NULL, &poll_max_ns_info); |
5e5db499 SH |
264 | object_class_property_add(klass, "poll-grow", "int", |
265 | iothread_get_poll_param, | |
266 | iothread_set_poll_param, | |
d2623129 | 267 | NULL, &poll_grow_info); |
5e5db499 SH |
268 | object_class_property_add(klass, "poll-shrink", "int", |
269 | iothread_get_poll_param, | |
270 | iothread_set_poll_param, | |
d2623129 | 271 | NULL, &poll_shrink_info); |
be8d8537 SH |
272 | } |
273 | ||
274 | static const TypeInfo iothread_info = { | |
275 | .name = TYPE_IOTHREAD, | |
276 | .parent = TYPE_OBJECT, | |
277 | .class_init = iothread_class_init, | |
278 | .instance_size = sizeof(IOThread), | |
cdd7abfd | 279 | .instance_init = iothread_instance_init, |
be8d8537 SH |
280 | .instance_finalize = iothread_instance_finalize, |
281 | .interfaces = (InterfaceInfo[]) { | |
282 | {TYPE_USER_CREATABLE}, | |
283 | {} | |
284 | }, | |
285 | }; | |
286 | ||
287 | static void iothread_register_types(void) | |
288 | { | |
289 | type_register_static(&iothread_info); | |
290 | } | |
291 | ||
292 | type_init(iothread_register_types) | |
293 | ||
be8d8537 SH |
294 | char *iothread_get_id(IOThread *iothread) |
295 | { | |
7a309cc9 | 296 | return g_strdup(object_get_canonical_path_component(OBJECT(iothread))); |
be8d8537 SH |
297 | } |
298 | ||
299 | AioContext *iothread_get_aio_context(IOThread *iothread) | |
300 | { | |
301 | return iothread->ctx; | |
302 | } | |
dc3dd0d2 SH |
303 | |
304 | static int query_one_iothread(Object *object, void *opaque) | |
305 | { | |
c3033fd3 | 306 | IOThreadInfoList ***tail = opaque; |
dc3dd0d2 SH |
307 | IOThreadInfo *info; |
308 | IOThread *iothread; | |
309 | ||
310 | iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD); | |
311 | if (!iothread) { | |
312 | return 0; | |
313 | } | |
314 | ||
315 | info = g_new0(IOThreadInfo, 1); | |
316 | info->id = iothread_get_id(iothread); | |
317 | info->thread_id = iothread->thread_id; | |
5fc00480 PH |
318 | info->poll_max_ns = iothread->poll_max_ns; |
319 | info->poll_grow = iothread->poll_grow; | |
320 | info->poll_shrink = iothread->poll_shrink; | |
dc3dd0d2 | 321 | |
c3033fd3 | 322 | QAPI_LIST_APPEND(*tail, info); |
dc3dd0d2 SH |
323 | return 0; |
324 | } | |
325 | ||
326 | IOThreadInfoList *qmp_query_iothreads(Error **errp) | |
327 | { | |
328 | IOThreadInfoList *head = NULL; | |
329 | IOThreadInfoList **prev = &head; | |
bc2256c4 | 330 | Object *container = object_get_objects_root(); |
dc3dd0d2 SH |
331 | |
332 | object_child_foreach(container, query_one_iothread, &prev); | |
333 | return head; | |
334 | } | |
dce8921b | 335 | |
329163cb WY |
336 | GMainContext *iothread_get_g_main_context(IOThread *iothread) |
337 | { | |
d73415a3 | 338 | qatomic_set(&iothread->run_gcontext, 1); |
b506e0f1 | 339 | aio_notify(iothread->ctx); |
329163cb WY |
340 | return iothread->worker_context; |
341 | } | |
0173e21b PX |
342 | |
343 | IOThread *iothread_create(const char *id, Error **errp) | |
344 | { | |
345 | Object *obj; | |
346 | ||
347 | obj = object_new_with_props(TYPE_IOTHREAD, | |
348 | object_get_internal_root(), | |
349 | id, errp, NULL); | |
350 | ||
351 | return IOTHREAD(obj); | |
352 | } | |
353 | ||
354 | void iothread_destroy(IOThread *iothread) | |
355 | { | |
356 | object_unparent(OBJECT(iothread)); | |
357 | } | |
fbcc6923 SH |
358 | |
359 | /* Lookup IOThread by its id. Only finds user-created objects, not internal | |
360 | * iothread_create() objects. */ | |
361 | IOThread *iothread_by_id(const char *id) | |
362 | { | |
363 | return IOTHREAD(object_resolve_path_type(id, TYPE_IOTHREAD, NULL)); | |
364 | } | |
ad22c308 EU |
365 | |
366 | bool qemu_in_iothread(void) | |
367 | { | |
368 | return qemu_get_current_aio_context() == qemu_get_aio_context() ? | |
369 | false : true; | |
370 | } |