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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 (!atomic_read(&iothread->stopping)) { | |
59 | aio_poll(iothread->ctx, true); | |
60 | } | |
61 | ||
62 | rcu_unregister_thread(); | |
63 | return NULL; | |
64 | } | |
65 | ||
66 | static int iothread_stop(Object *object, void *opaque) | |
67 | { | |
68 | IOThread *iothread; | |
69 | ||
70 | iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD); | |
71 | if (!iothread || !iothread->ctx) { | |
72 | return 0; | |
73 | } | |
74 | iothread->stopping = true; | |
75 | aio_notify(iothread->ctx); | |
76 | qemu_thread_join(&iothread->thread); | |
77 | return 0; | |
78 | } | |
79 | ||
80 | static void iothread_instance_init(Object *obj) | |
81 | { | |
82 | IOThread *iothread = IOTHREAD(obj); | |
83 | ||
84 | iothread->poll_max_ns = IOTHREAD_POLL_MAX_NS_DEFAULT; | |
85 | } | |
86 | ||
87 | static void iothread_instance_finalize(Object *obj) | |
88 | { | |
89 | IOThread *iothread = IOTHREAD(obj); | |
90 | ||
91 | iothread_stop(obj, NULL); | |
92 | qemu_cond_destroy(&iothread->init_done_cond); | |
93 | qemu_mutex_destroy(&iothread->init_done_lock); | |
94 | if (!iothread->ctx) { | |
95 | return; | |
96 | } | |
97 | aio_context_unref(iothread->ctx); | |
98 | } | |
99 | ||
100 | static void iothread_complete(UserCreatable *obj, Error **errp) | |
101 | { | |
102 | Error *local_error = NULL; | |
103 | IOThread *iothread = IOTHREAD(obj); | |
104 | char *name, *thread_name; | |
105 | ||
106 | iothread->stopping = false; | |
107 | iothread->thread_id = -1; | |
108 | iothread->ctx = aio_context_new(&local_error); | |
109 | if (!iothread->ctx) { | |
110 | error_propagate(errp, local_error); | |
111 | return; | |
112 | } | |
113 | ||
114 | aio_context_set_poll_params(iothread->ctx, | |
115 | iothread->poll_max_ns, | |
116 | iothread->poll_grow, | |
117 | iothread->poll_shrink, | |
118 | &local_error); | |
119 | if (local_error) { | |
120 | error_propagate(errp, local_error); | |
121 | aio_context_unref(iothread->ctx); | |
122 | iothread->ctx = NULL; | |
123 | return; | |
124 | } | |
125 | ||
126 | qemu_mutex_init(&iothread->init_done_lock); | |
127 | qemu_cond_init(&iothread->init_done_cond); | |
128 | ||
129 | /* This assumes we are called from a thread with useful CPU affinity for us | |
130 | * to inherit. | |
131 | */ | |
132 | name = object_get_canonical_path_component(OBJECT(obj)); | |
133 | thread_name = g_strdup_printf("IO %s", name); | |
134 | qemu_thread_create(&iothread->thread, thread_name, iothread_run, | |
135 | iothread, QEMU_THREAD_JOINABLE); | |
136 | g_free(thread_name); | |
137 | g_free(name); | |
138 | ||
139 | /* Wait for initialization to complete */ | |
140 | qemu_mutex_lock(&iothread->init_done_lock); | |
141 | while (iothread->thread_id == -1) { | |
142 | qemu_cond_wait(&iothread->init_done_cond, | |
143 | &iothread->init_done_lock); | |
144 | } | |
145 | qemu_mutex_unlock(&iothread->init_done_lock); | |
146 | } | |
147 | ||
148 | typedef struct { | |
149 | const char *name; | |
150 | ptrdiff_t offset; /* field's byte offset in IOThread struct */ | |
151 | } PollParamInfo; | |
152 | ||
153 | static PollParamInfo poll_max_ns_info = { | |
154 | "poll-max-ns", offsetof(IOThread, poll_max_ns), | |
155 | }; | |
156 | static PollParamInfo poll_grow_info = { | |
157 | "poll-grow", offsetof(IOThread, poll_grow), | |
158 | }; | |
159 | static PollParamInfo poll_shrink_info = { | |
160 | "poll-shrink", offsetof(IOThread, poll_shrink), | |
161 | }; | |
162 | ||
163 | static void iothread_get_poll_param(Object *obj, Visitor *v, | |
164 | const char *name, void *opaque, Error **errp) | |
165 | { | |
166 | IOThread *iothread = IOTHREAD(obj); | |
167 | PollParamInfo *info = opaque; | |
168 | int64_t *field = (void *)iothread + info->offset; | |
169 | ||
170 | visit_type_int64(v, name, field, errp); | |
171 | } | |
172 | ||
173 | static void iothread_set_poll_param(Object *obj, Visitor *v, | |
174 | const char *name, void *opaque, Error **errp) | |
175 | { | |
176 | IOThread *iothread = IOTHREAD(obj); | |
177 | PollParamInfo *info = opaque; | |
178 | int64_t *field = (void *)iothread + info->offset; | |
179 | Error *local_err = NULL; | |
180 | int64_t value; | |
181 | ||
182 | visit_type_int64(v, name, &value, &local_err); | |
183 | if (local_err) { | |
184 | goto out; | |
185 | } | |
186 | ||
187 | if (value < 0) { | |
188 | error_setg(&local_err, "%s value must be in range [0, %"PRId64"]", | |
189 | info->name, INT64_MAX); | |
190 | goto out; | |
191 | } | |
192 | ||
193 | *field = value; | |
194 | ||
195 | if (iothread->ctx) { | |
196 | aio_context_set_poll_params(iothread->ctx, | |
197 | iothread->poll_max_ns, | |
198 | iothread->poll_grow, | |
199 | iothread->poll_shrink, | |
200 | &local_err); | |
201 | } | |
202 | ||
203 | out: | |
204 | error_propagate(errp, local_err); | |
205 | } | |
206 | ||
207 | static void iothread_class_init(ObjectClass *klass, void *class_data) | |
208 | { | |
209 | UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass); | |
210 | ucc->complete = iothread_complete; | |
211 | ||
212 | object_class_property_add(klass, "poll-max-ns", "int", | |
213 | iothread_get_poll_param, | |
214 | iothread_set_poll_param, | |
215 | NULL, &poll_max_ns_info, &error_abort); | |
216 | object_class_property_add(klass, "poll-grow", "int", | |
217 | iothread_get_poll_param, | |
218 | iothread_set_poll_param, | |
219 | NULL, &poll_grow_info, &error_abort); | |
220 | object_class_property_add(klass, "poll-shrink", "int", | |
221 | iothread_get_poll_param, | |
222 | iothread_set_poll_param, | |
223 | NULL, &poll_shrink_info, &error_abort); | |
224 | } | |
225 | ||
226 | static const TypeInfo iothread_info = { | |
227 | .name = TYPE_IOTHREAD, | |
228 | .parent = TYPE_OBJECT, | |
229 | .class_init = iothread_class_init, | |
230 | .instance_size = sizeof(IOThread), | |
231 | .instance_init = iothread_instance_init, | |
232 | .instance_finalize = iothread_instance_finalize, | |
233 | .interfaces = (InterfaceInfo[]) { | |
234 | {TYPE_USER_CREATABLE}, | |
235 | {} | |
236 | }, | |
237 | }; | |
238 | ||
239 | static void iothread_register_types(void) | |
240 | { | |
241 | type_register_static(&iothread_info); | |
242 | } | |
243 | ||
244 | type_init(iothread_register_types) | |
245 | ||
246 | char *iothread_get_id(IOThread *iothread) | |
247 | { | |
248 | return object_get_canonical_path_component(OBJECT(iothread)); | |
249 | } | |
250 | ||
251 | AioContext *iothread_get_aio_context(IOThread *iothread) | |
252 | { | |
253 | return iothread->ctx; | |
254 | } | |
255 | ||
256 | static int query_one_iothread(Object *object, void *opaque) | |
257 | { | |
258 | IOThreadInfoList ***prev = opaque; | |
259 | IOThreadInfoList *elem; | |
260 | IOThreadInfo *info; | |
261 | IOThread *iothread; | |
262 | ||
263 | iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD); | |
264 | if (!iothread) { | |
265 | return 0; | |
266 | } | |
267 | ||
268 | info = g_new0(IOThreadInfo, 1); | |
269 | info->id = iothread_get_id(iothread); | |
270 | info->thread_id = iothread->thread_id; | |
271 | info->poll_max_ns = iothread->poll_max_ns; | |
272 | info->poll_grow = iothread->poll_grow; | |
273 | info->poll_shrink = iothread->poll_shrink; | |
274 | ||
275 | elem = g_new0(IOThreadInfoList, 1); | |
276 | elem->value = info; | |
277 | elem->next = NULL; | |
278 | ||
279 | **prev = elem; | |
280 | *prev = &elem->next; | |
281 | return 0; | |
282 | } | |
283 | ||
284 | IOThreadInfoList *qmp_query_iothreads(Error **errp) | |
285 | { | |
286 | IOThreadInfoList *head = NULL; | |
287 | IOThreadInfoList **prev = &head; | |
288 | Object *container = object_get_objects_root(); | |
289 | ||
290 | object_child_foreach(container, query_one_iothread, &prev); | |
291 | return head; | |
292 | } | |
293 | ||
294 | void iothread_stop_all(void) | |
295 | { | |
296 | Object *container = object_get_objects_root(); | |
297 | BlockDriverState *bs; | |
298 | BdrvNextIterator it; | |
299 | ||
300 | for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { | |
301 | AioContext *ctx = bdrv_get_aio_context(bs); | |
302 | if (ctx == qemu_get_aio_context()) { | |
303 | continue; | |
304 | } | |
305 | aio_context_acquire(ctx); | |
306 | bdrv_set_aio_context(bs, qemu_get_aio_context()); | |
307 | aio_context_release(ctx); | |
308 | } | |
309 | ||
310 | object_child_foreach(container, iothread_stop, NULL); | |
311 | } |