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Stefan Hajnoczibe8d8532014-03-03 11:30:05 +01001/*
2 * Event loop thread
3 *
Eric Blakec3033fd2021-01-13 16:10:12 -06004 * Copyright Red Hat Inc., 2013, 2020
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +01005 *
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
Peter Maydelld38ea872016-01-29 17:50:05 +000014#include "qemu/osdep.h"
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +010015#include "qom/object.h"
16#include "qom/object_interfaces.h"
17#include "qemu/module.h"
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +010018#include "block/aio.h"
Paolo Bonzinid16341f2016-10-27 12:49:00 +020019#include "block/block.h"
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +010020#include "sysemu/iothread.h"
Markus Armbrustere688df62018-02-01 12:18:31 +010021#include "qapi/error.h"
Markus Armbruster112ed242018-02-26 17:13:27 -060022#include "qapi/qapi-commands-misc.h"
Chrysostomos Nanakos2f78e492014-09-18 14:30:49 +030023#include "qemu/error-report.h"
Paolo Bonziniab28bd22015-07-09 08:55:38 +020024#include "qemu/rcu.h"
Paolo Bonzinie4370162016-10-27 12:48:59 +020025#include "qemu/main-loop.h"
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +010026
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +010027typedef ObjectClass IOThreadClass;
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +010028
Eduardo Habkost8110fa12020-08-31 17:07:33 -040029DECLARE_CLASS_CHECKERS(IOThreadClass, IOTHREAD,
30 TYPE_IOTHREAD)
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +010031
Peter Xu90c558b2018-03-22 16:56:30 +080032#ifdef CONFIG_POSIX
Stefan Hajnoczicdd7abf2017-01-26 17:01:19 +000033/* 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
Peter Xu90c558b2018-03-22 16:56:30 +080038#else
39#define IOTHREAD_POLL_MAX_NS_DEFAULT 0ULL
40#endif
Stefan Hajnoczicdd7abf2017-01-26 17:01:19 +000041
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +010042static void *iothread_run(void *opaque)
43{
44 IOThread *iothread = opaque;
45
Paolo Bonziniab28bd22015-07-09 08:55:38 +020046 rcu_register_thread();
Peter Xub60ec762019-03-06 19:55:31 +080047 /*
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);
Paolo Bonzini5f50be92021-06-09 14:22:34 +020052 qemu_set_current_aio_context(iothread->ctx);
Stefan Hajnoczi88eb7c22014-02-27 11:48:41 +010053 iothread->thread_id = qemu_get_thread_id();
Peter Xu21c4d152019-03-06 19:55:28 +080054 qemu_sem_post(&iothread->init_done_sem);
Stefan Hajnoczi88eb7c22014-02-27 11:48:41 +010055
Stefan Hajnoczi2362a282017-12-07 20:13:19 +000056 while (iothread->running) {
Peter Xu6ca20622019-03-06 19:55:32 +080057 /*
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 */
Paolo Bonzini65c1b5b2016-10-27 12:49:06 +020066 aio_poll(iothread->ctx, true);
Wang Yong329163c2017-08-29 15:22:37 +080067
Peter Xu6c953632019-01-29 13:14:32 +080068 /*
69 * We must check the running state again in case it was
70 * changed in previous aio_poll()
71 */
Stefan Hajnoczid73415a2020-09-23 11:56:46 +010072 if (iothread->running && qatomic_read(&iothread->run_gcontext)) {
Wang Yong329163c2017-08-29 15:22:37 +080073 g_main_loop_run(iothread->main_loop);
Wang Yong329163c2017-08-29 15:22:37 +080074 }
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +010075 }
Paolo Bonziniab28bd22015-07-09 08:55:38 +020076
Peter Xub60ec762019-03-06 19:55:31 +080077 g_main_context_pop_thread_default(iothread->worker_context);
Paolo Bonziniab28bd22015-07-09 08:55:38 +020078 rcu_unregister_thread();
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +010079 return NULL;
80}
81
Stefan Hajnoczi2362a282017-12-07 20:13:19 +000082/* Runs in iothread_run() thread */
83static 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
Peter Xu82d90702017-09-28 10:59:56 +080094void iothread_stop(IOThread *iothread)
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +010095{
Peter Xu82d90702017-09-28 10:59:56 +080096 if (!iothread->ctx || iothread->stopping) {
97 return;
Chrysostomos Nanakos2f78e492014-09-18 14:30:49 +030098 }
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +010099 iothread->stopping = true;
Stefan Hajnoczi2362a282017-12-07 20:13:19 +0000100 aio_bh_schedule_oneshot(iothread->ctx, iothread_stop_bh, iothread);
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +0100101 qemu_thread_join(&iothread->thread);
Peter Xu82d90702017-09-28 10:59:56 +0800102}
103
Stefan Hajnoczicdd7abf2017-01-26 17:01:19 +0000104static void iothread_instance_init(Object *obj)
105{
106 IOThread *iothread = IOTHREAD(obj);
107
108 iothread->poll_max_ns = IOTHREAD_POLL_MAX_NS_DEFAULT;
Marc-André Lureau14a2d112018-08-21 12:07:16 +0200109 iothread->thread_id = -1;
Peter Xu21c4d152019-03-06 19:55:28 +0800110 qemu_sem_init(&iothread->init_done_sem, 0);
Peter Xub506e0f2019-03-06 19:55:29 +0800111 /* By default, we don't run gcontext */
Stefan Hajnoczid73415a2020-09-23 11:56:46 +0100112 qatomic_set(&iothread->run_gcontext, 0);
Stefan Hajnoczicdd7abf2017-01-26 17:01:19 +0000113}
114
Fam Zhengdce89212016-09-08 17:28:51 +0800115static void iothread_instance_finalize(Object *obj)
116{
117 IOThread *iothread = IOTHREAD(obj);
118
Peter Xu82d90702017-09-28 10:59:56 +0800119 iothread_stop(iothread);
Marc-André Lureau14a2d112018-08-21 12:07:16 +0200120
Peter Xu15544342018-04-09 16:39:56 +0800121 /*
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 }
Peter Xu5b3ac232017-09-28 10:59:57 +0800135 if (iothread->worker_context) {
136 g_main_context_unref(iothread->worker_context);
137 iothread->worker_context = NULL;
Peter Xu0bd2d232019-03-06 19:55:30 +0800138 g_main_loop_unref(iothread->main_loop);
139 iothread->main_loop = NULL;
Peter Xu5b3ac232017-09-28 10:59:57 +0800140 }
Peter Xu21c4d152019-03-06 19:55:28 +0800141 qemu_sem_destroy(&iothread->init_done_sem);
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +0100142}
143
Peter Xub506e0f2019-03-06 19:55:29 +0800144static 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);
Peter Xu0bd2d232019-03-06 19:55:30 +0800152 iothread->main_loop = g_main_loop_new(iothread->worker_context, TRUE);
Peter Xub506e0f2019-03-06 19:55:29 +0800153}
154
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +0100155static void iothread_complete(UserCreatable *obj, Error **errp)
156{
Chrysostomos Nanakos2f78e492014-09-18 14:30:49 +0300157 Error *local_error = NULL;
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +0100158 IOThread *iothread = IOTHREAD(obj);
Markus Armbruster7a309cc2020-07-14 18:02:00 +0200159 char *thread_name;
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +0100160
161 iothread->stopping = false;
Stefan Hajnoczi2362a282017-12-07 20:13:19 +0000162 iothread->running = true;
Markus Armbruster668f62e2020-07-07 18:06:02 +0200163 iothread->ctx = aio_context_new(errp);
Chrysostomos Nanakos2f78e492014-09-18 14:30:49 +0300164 if (!iothread->ctx) {
Chrysostomos Nanakos2f78e492014-09-18 14:30:49 +0300165 return;
166 }
Stefan Hajnoczi88eb7c22014-02-27 11:48:41 +0100167
Peter Xub506e0f2019-03-06 19:55:29 +0800168 /*
169 * Init one GMainContext for the iothread unconditionally, even if
170 * it's not used
171 */
172 iothread_init_gcontext(iothread);
173
Stefan Hajnoczi5e5db492016-12-01 19:26:52 +0000174 aio_context_set_poll_params(iothread->ctx,
175 iothread->poll_max_ns,
176 iothread->poll_grow,
177 iothread->poll_shrink,
Stefan Hajnoczi0d9d86f2016-12-01 19:26:45 +0000178 &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
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +0100186 /* This assumes we are called from a thread with useful CPU affinity for us
187 * to inherit.
188 */
Markus Armbruster7a309cc2020-07-14 18:02:00 +0200189 thread_name = g_strdup_printf("IO %s",
190 object_get_canonical_path_component(OBJECT(obj)));
Paolo Bonzinid21e8772015-11-24 14:46:44 +0100191 qemu_thread_create(&iothread->thread, thread_name, iothread_run,
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +0100192 iothread, QEMU_THREAD_JOINABLE);
Paolo Bonzinid21e8772015-11-24 14:46:44 +0100193 g_free(thread_name);
Stefan Hajnoczi88eb7c22014-02-27 11:48:41 +0100194
195 /* Wait for initialization to complete */
Stefan Hajnoczi88eb7c22014-02-27 11:48:41 +0100196 while (iothread->thread_id == -1) {
Peter Xu21c4d152019-03-06 19:55:28 +0800197 qemu_sem_wait(&iothread->init_done_sem);
Stefan Hajnoczi88eb7c22014-02-27 11:48:41 +0100198 }
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +0100199}
200
Stefan Hajnoczi5e5db492016-12-01 19:26:52 +0000201typedef struct {
202 const char *name;
203 ptrdiff_t offset; /* field's byte offset in IOThread struct */
204} PollParamInfo;
205
206static PollParamInfo poll_max_ns_info = {
207 "poll-max-ns", offsetof(IOThread, poll_max_ns),
208};
209static PollParamInfo poll_grow_info = {
210 "poll-grow", offsetof(IOThread, poll_grow),
211};
212static PollParamInfo poll_shrink_info = {
213 "poll-shrink", offsetof(IOThread, poll_shrink),
214};
215
216static void iothread_get_poll_param(Object *obj, Visitor *v,
Stefan Hajnoczi0d9d86f2016-12-01 19:26:45 +0000217 const char *name, void *opaque, Error **errp)
218{
219 IOThread *iothread = IOTHREAD(obj);
Stefan Hajnoczi5e5db492016-12-01 19:26:52 +0000220 PollParamInfo *info = opaque;
221 int64_t *field = (void *)iothread + info->offset;
Stefan Hajnoczi0d9d86f2016-12-01 19:26:45 +0000222
Stefan Hajnoczi5e5db492016-12-01 19:26:52 +0000223 visit_type_int64(v, name, field, errp);
Stefan Hajnoczi0d9d86f2016-12-01 19:26:45 +0000224}
225
Stefan Hajnoczi5e5db492016-12-01 19:26:52 +0000226static void iothread_set_poll_param(Object *obj, Visitor *v,
Stefan Hajnoczi0d9d86f2016-12-01 19:26:45 +0000227 const char *name, void *opaque, Error **errp)
228{
229 IOThread *iothread = IOTHREAD(obj);
Stefan Hajnoczi5e5db492016-12-01 19:26:52 +0000230 PollParamInfo *info = opaque;
231 int64_t *field = (void *)iothread + info->offset;
Stefan Hajnoczi0d9d86f2016-12-01 19:26:45 +0000232 int64_t value;
233
Markus Armbruster668f62e2020-07-07 18:06:02 +0200234 if (!visit_type_int64(v, name, &value, errp)) {
Markus Armbrusterdcfe4802020-07-07 18:06:01 +0200235 return;
Stefan Hajnoczi0d9d86f2016-12-01 19:26:45 +0000236 }
237
238 if (value < 0) {
Markus Armbrusterdcfe4802020-07-07 18:06:01 +0200239 error_setg(errp, "%s value must be in range [0, %" PRId64 "]",
Stefan Hajnoczi5e5db492016-12-01 19:26:52 +0000240 info->name, INT64_MAX);
Markus Armbrusterdcfe4802020-07-07 18:06:01 +0200241 return;
Stefan Hajnoczi0d9d86f2016-12-01 19:26:45 +0000242 }
243
Stefan Hajnoczi5e5db492016-12-01 19:26:52 +0000244 *field = value;
Stefan Hajnoczi0d9d86f2016-12-01 19:26:45 +0000245
246 if (iothread->ctx) {
Stefan Hajnoczi5e5db492016-12-01 19:26:52 +0000247 aio_context_set_poll_params(iothread->ctx,
248 iothread->poll_max_ns,
249 iothread->poll_grow,
250 iothread->poll_shrink,
Markus Armbrusterdcfe4802020-07-07 18:06:01 +0200251 errp);
Stefan Hajnoczi0d9d86f2016-12-01 19:26:45 +0000252 }
Stefan Hajnoczi0d9d86f2016-12-01 19:26:45 +0000253}
254
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +0100255static void iothread_class_init(ObjectClass *klass, void *class_data)
256{
257 UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
258 ucc->complete = iothread_complete;
Stefan Hajnoczi0d9d86f2016-12-01 19:26:45 +0000259
260 object_class_property_add(klass, "poll-max-ns", "int",
Stefan Hajnoczi5e5db492016-12-01 19:26:52 +0000261 iothread_get_poll_param,
262 iothread_set_poll_param,
Markus Armbrusterd2623122020-05-05 17:29:22 +0200263 NULL, &poll_max_ns_info);
Stefan Hajnoczi5e5db492016-12-01 19:26:52 +0000264 object_class_property_add(klass, "poll-grow", "int",
265 iothread_get_poll_param,
266 iothread_set_poll_param,
Markus Armbrusterd2623122020-05-05 17:29:22 +0200267 NULL, &poll_grow_info);
Stefan Hajnoczi5e5db492016-12-01 19:26:52 +0000268 object_class_property_add(klass, "poll-shrink", "int",
269 iothread_get_poll_param,
270 iothread_set_poll_param,
Markus Armbrusterd2623122020-05-05 17:29:22 +0200271 NULL, &poll_shrink_info);
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +0100272}
273
274static const TypeInfo iothread_info = {
275 .name = TYPE_IOTHREAD,
276 .parent = TYPE_OBJECT,
277 .class_init = iothread_class_init,
278 .instance_size = sizeof(IOThread),
Stefan Hajnoczicdd7abf2017-01-26 17:01:19 +0000279 .instance_init = iothread_instance_init,
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +0100280 .instance_finalize = iothread_instance_finalize,
281 .interfaces = (InterfaceInfo[]) {
282 {TYPE_USER_CREATABLE},
283 {}
284 },
285};
286
287static void iothread_register_types(void)
288{
289 type_register_static(&iothread_info);
290}
291
292type_init(iothread_register_types)
293
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +0100294char *iothread_get_id(IOThread *iothread)
295{
Markus Armbruster7a309cc2020-07-14 18:02:00 +0200296 return g_strdup(object_get_canonical_path_component(OBJECT(iothread)));
Stefan Hajnoczibe8d8532014-03-03 11:30:05 +0100297}
298
299AioContext *iothread_get_aio_context(IOThread *iothread)
300{
301 return iothread->ctx;
302}
Stefan Hajnoczidc3dd0d2014-02-27 11:48:42 +0100303
304static int query_one_iothread(Object *object, void *opaque)
305{
Eric Blakec3033fd2021-01-13 16:10:12 -0600306 IOThreadInfoList ***tail = opaque;
Stefan Hajnoczidc3dd0d2014-02-27 11:48:42 +0100307 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;
Pavel Hrdina5fc00482017-02-10 10:41:17 +0100318 info->poll_max_ns = iothread->poll_max_ns;
319 info->poll_grow = iothread->poll_grow;
320 info->poll_shrink = iothread->poll_shrink;
Stefan Hajnoczidc3dd0d2014-02-27 11:48:42 +0100321
Eric Blakec3033fd2021-01-13 16:10:12 -0600322 QAPI_LIST_APPEND(*tail, info);
Stefan Hajnoczidc3dd0d2014-02-27 11:48:42 +0100323 return 0;
324}
325
326IOThreadInfoList *qmp_query_iothreads(Error **errp)
327{
328 IOThreadInfoList *head = NULL;
329 IOThreadInfoList **prev = &head;
Daniel P. Berrangebc2256c2015-05-13 17:14:05 +0100330 Object *container = object_get_objects_root();
Stefan Hajnoczidc3dd0d2014-02-27 11:48:42 +0100331
332 object_child_foreach(container, query_one_iothread, &prev);
333 return head;
334}
Fam Zhengdce89212016-09-08 17:28:51 +0800335
Wang Yong329163c2017-08-29 15:22:37 +0800336GMainContext *iothread_get_g_main_context(IOThread *iothread)
337{
Stefan Hajnoczid73415a2020-09-23 11:56:46 +0100338 qatomic_set(&iothread->run_gcontext, 1);
Peter Xub506e0f2019-03-06 19:55:29 +0800339 aio_notify(iothread->ctx);
Wang Yong329163c2017-08-29 15:22:37 +0800340 return iothread->worker_context;
341}
Peter Xu0173e212017-09-28 10:59:55 +0800342
343IOThread *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
354void iothread_destroy(IOThread *iothread)
355{
356 object_unparent(OBJECT(iothread));
357}
Stefan Hajnoczifbcc6922017-12-06 14:45:48 +0000358
359/* Lookup IOThread by its id. Only finds user-created objects, not internal
360 * iothread_create() objects. */
361IOThread *iothread_by_id(const char *id)
362{
363 return IOTHREAD(object_resolve_path_type(id, TYPE_IOTHREAD, NULL));
364}
Elena Ufimtsevaad22c302021-01-29 11:46:10 -0500365
366bool qemu_in_iothread(void)
367{
368 return qemu_get_current_aio_context() == qemu_get_aio_context() ?
369 false : true;
370}