target/arm: Allow execution from small regions
[qemu/ar7.git] / iothread.c
blobaff128125769c384a019dfef8d6c354752600012
1 /*
2 * Event loop thread
4 * Copyright Red Hat Inc., 2013
6 * Authors:
7 * Stefan Hajnoczi <stefanha@redhat.com>
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.
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 "qapi/error.h"
22 #include "qapi/qapi-commands-misc.h"
23 #include "qemu/error-report.h"
24 #include "qemu/rcu.h"
25 #include "qemu/main-loop.h"
27 typedef ObjectClass IOThreadClass;
29 #define IOTHREAD_GET_CLASS(obj) \
30 OBJECT_GET_CLASS(IOThreadClass, obj, TYPE_IOTHREAD)
31 #define IOTHREAD_CLASS(klass) \
32 OBJECT_CLASS_CHECK(IOThreadClass, klass, TYPE_IOTHREAD)
34 #ifdef CONFIG_POSIX
35 /* Benchmark results from 2016 on NVMe SSD drives show max polling times around
36 * 16-32 microseconds yield IOPS improvements for both iodepth=1 and iodepth=32
37 * workloads.
39 #define IOTHREAD_POLL_MAX_NS_DEFAULT 32768ULL
40 #else
41 #define IOTHREAD_POLL_MAX_NS_DEFAULT 0ULL
42 #endif
44 static __thread IOThread *my_iothread;
46 AioContext *qemu_get_current_aio_context(void)
48 return my_iothread ? my_iothread->ctx : qemu_get_aio_context();
51 static void *iothread_run(void *opaque)
53 IOThread *iothread = opaque;
55 rcu_register_thread();
57 my_iothread = iothread;
58 qemu_mutex_lock(&iothread->init_done_lock);
59 iothread->thread_id = qemu_get_thread_id();
60 qemu_cond_signal(&iothread->init_done_cond);
61 qemu_mutex_unlock(&iothread->init_done_lock);
63 while (iothread->running) {
64 aio_poll(iothread->ctx, true);
66 if (atomic_read(&iothread->worker_context)) {
67 GMainLoop *loop;
69 g_main_context_push_thread_default(iothread->worker_context);
70 iothread->main_loop =
71 g_main_loop_new(iothread->worker_context, TRUE);
72 loop = iothread->main_loop;
74 g_main_loop_run(iothread->main_loop);
75 iothread->main_loop = NULL;
76 g_main_loop_unref(loop);
78 g_main_context_pop_thread_default(iothread->worker_context);
82 rcu_unregister_thread();
83 return NULL;
86 /* Runs in iothread_run() thread */
87 static void iothread_stop_bh(void *opaque)
89 IOThread *iothread = opaque;
91 iothread->running = false; /* stop iothread_run() */
93 if (iothread->main_loop) {
94 g_main_loop_quit(iothread->main_loop);
98 void iothread_stop(IOThread *iothread)
100 if (!iothread->ctx || iothread->stopping) {
101 return;
103 iothread->stopping = true;
104 aio_bh_schedule_oneshot(iothread->ctx, iothread_stop_bh, iothread);
105 qemu_thread_join(&iothread->thread);
108 static void iothread_instance_init(Object *obj)
110 IOThread *iothread = IOTHREAD(obj);
112 iothread->poll_max_ns = IOTHREAD_POLL_MAX_NS_DEFAULT;
115 static void iothread_instance_finalize(Object *obj)
117 IOThread *iothread = IOTHREAD(obj);
119 iothread_stop(iothread);
121 * Before glib2 2.33.10, there is a glib2 bug that GSource context
122 * pointer may not be cleared even if the context has already been
123 * destroyed (while it should). Here let's free the AIO context
124 * earlier to bypass that glib bug.
126 * We can remove this comment after the minimum supported glib2
127 * version boosts to 2.33.10. Before that, let's free the
128 * GSources first before destroying any GMainContext.
130 if (iothread->ctx) {
131 aio_context_unref(iothread->ctx);
132 iothread->ctx = NULL;
134 if (iothread->worker_context) {
135 g_main_context_unref(iothread->worker_context);
136 iothread->worker_context = NULL;
138 qemu_cond_destroy(&iothread->init_done_cond);
139 qemu_mutex_destroy(&iothread->init_done_lock);
142 static void iothread_complete(UserCreatable *obj, Error **errp)
144 Error *local_error = NULL;
145 IOThread *iothread = IOTHREAD(obj);
146 char *name, *thread_name;
148 iothread->stopping = false;
149 iothread->running = true;
150 iothread->thread_id = -1;
151 iothread->ctx = aio_context_new(&local_error);
152 if (!iothread->ctx) {
153 error_propagate(errp, local_error);
154 return;
157 aio_context_set_poll_params(iothread->ctx,
158 iothread->poll_max_ns,
159 iothread->poll_grow,
160 iothread->poll_shrink,
161 &local_error);
162 if (local_error) {
163 error_propagate(errp, local_error);
164 aio_context_unref(iothread->ctx);
165 iothread->ctx = NULL;
166 return;
169 qemu_mutex_init(&iothread->init_done_lock);
170 qemu_cond_init(&iothread->init_done_cond);
171 iothread->once = (GOnce) G_ONCE_INIT;
173 /* This assumes we are called from a thread with useful CPU affinity for us
174 * to inherit.
176 name = object_get_canonical_path_component(OBJECT(obj));
177 thread_name = g_strdup_printf("IO %s", name);
178 qemu_thread_create(&iothread->thread, thread_name, iothread_run,
179 iothread, QEMU_THREAD_JOINABLE);
180 g_free(thread_name);
181 g_free(name);
183 /* Wait for initialization to complete */
184 qemu_mutex_lock(&iothread->init_done_lock);
185 while (iothread->thread_id == -1) {
186 qemu_cond_wait(&iothread->init_done_cond,
187 &iothread->init_done_lock);
189 qemu_mutex_unlock(&iothread->init_done_lock);
192 typedef struct {
193 const char *name;
194 ptrdiff_t offset; /* field's byte offset in IOThread struct */
195 } PollParamInfo;
197 static PollParamInfo poll_max_ns_info = {
198 "poll-max-ns", offsetof(IOThread, poll_max_ns),
200 static PollParamInfo poll_grow_info = {
201 "poll-grow", offsetof(IOThread, poll_grow),
203 static PollParamInfo poll_shrink_info = {
204 "poll-shrink", offsetof(IOThread, poll_shrink),
207 static void iothread_get_poll_param(Object *obj, Visitor *v,
208 const char *name, void *opaque, Error **errp)
210 IOThread *iothread = IOTHREAD(obj);
211 PollParamInfo *info = opaque;
212 int64_t *field = (void *)iothread + info->offset;
214 visit_type_int64(v, name, field, errp);
217 static void iothread_set_poll_param(Object *obj, Visitor *v,
218 const char *name, void *opaque, Error **errp)
220 IOThread *iothread = IOTHREAD(obj);
221 PollParamInfo *info = opaque;
222 int64_t *field = (void *)iothread + info->offset;
223 Error *local_err = NULL;
224 int64_t value;
226 visit_type_int64(v, name, &value, &local_err);
227 if (local_err) {
228 goto out;
231 if (value < 0) {
232 error_setg(&local_err, "%s value must be in range [0, %"PRId64"]",
233 info->name, INT64_MAX);
234 goto out;
237 *field = value;
239 if (iothread->ctx) {
240 aio_context_set_poll_params(iothread->ctx,
241 iothread->poll_max_ns,
242 iothread->poll_grow,
243 iothread->poll_shrink,
244 &local_err);
247 out:
248 error_propagate(errp, local_err);
251 static void iothread_class_init(ObjectClass *klass, void *class_data)
253 UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
254 ucc->complete = iothread_complete;
256 object_class_property_add(klass, "poll-max-ns", "int",
257 iothread_get_poll_param,
258 iothread_set_poll_param,
259 NULL, &poll_max_ns_info, &error_abort);
260 object_class_property_add(klass, "poll-grow", "int",
261 iothread_get_poll_param,
262 iothread_set_poll_param,
263 NULL, &poll_grow_info, &error_abort);
264 object_class_property_add(klass, "poll-shrink", "int",
265 iothread_get_poll_param,
266 iothread_set_poll_param,
267 NULL, &poll_shrink_info, &error_abort);
270 static const TypeInfo iothread_info = {
271 .name = TYPE_IOTHREAD,
272 .parent = TYPE_OBJECT,
273 .class_init = iothread_class_init,
274 .instance_size = sizeof(IOThread),
275 .instance_init = iothread_instance_init,
276 .instance_finalize = iothread_instance_finalize,
277 .interfaces = (InterfaceInfo[]) {
278 {TYPE_USER_CREATABLE},
283 static void iothread_register_types(void)
285 type_register_static(&iothread_info);
288 type_init(iothread_register_types)
290 char *iothread_get_id(IOThread *iothread)
292 return object_get_canonical_path_component(OBJECT(iothread));
295 AioContext *iothread_get_aio_context(IOThread *iothread)
297 return iothread->ctx;
300 static int query_one_iothread(Object *object, void *opaque)
302 IOThreadInfoList ***prev = opaque;
303 IOThreadInfoList *elem;
304 IOThreadInfo *info;
305 IOThread *iothread;
307 iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
308 if (!iothread) {
309 return 0;
312 info = g_new0(IOThreadInfo, 1);
313 info->id = iothread_get_id(iothread);
314 info->thread_id = iothread->thread_id;
315 info->poll_max_ns = iothread->poll_max_ns;
316 info->poll_grow = iothread->poll_grow;
317 info->poll_shrink = iothread->poll_shrink;
319 elem = g_new0(IOThreadInfoList, 1);
320 elem->value = info;
321 elem->next = NULL;
323 **prev = elem;
324 *prev = &elem->next;
325 return 0;
328 IOThreadInfoList *qmp_query_iothreads(Error **errp)
330 IOThreadInfoList *head = NULL;
331 IOThreadInfoList **prev = &head;
332 Object *container = object_get_objects_root();
334 object_child_foreach(container, query_one_iothread, &prev);
335 return head;
338 static gpointer iothread_g_main_context_init(gpointer opaque)
340 AioContext *ctx;
341 IOThread *iothread = opaque;
342 GSource *source;
344 iothread->worker_context = g_main_context_new();
346 ctx = iothread_get_aio_context(iothread);
347 source = aio_get_g_source(ctx);
348 g_source_attach(source, iothread->worker_context);
349 g_source_unref(source);
351 aio_notify(iothread->ctx);
352 return NULL;
355 GMainContext *iothread_get_g_main_context(IOThread *iothread)
357 g_once(&iothread->once, iothread_g_main_context_init, iothread);
359 return iothread->worker_context;
362 IOThread *iothread_create(const char *id, Error **errp)
364 Object *obj;
366 obj = object_new_with_props(TYPE_IOTHREAD,
367 object_get_internal_root(),
368 id, errp, NULL);
370 return IOTHREAD(obj);
373 void iothread_destroy(IOThread *iothread)
375 object_unparent(OBJECT(iothread));
378 /* Lookup IOThread by its id. Only finds user-created objects, not internal
379 * iothread_create() objects. */
380 IOThread *iothread_by_id(const char *id)
382 return IOTHREAD(object_resolve_path_type(id, TYPE_IOTHREAD, NULL));