iothread.c

   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 static __thread IOThread *my_iothread;
  34
  35 AioContext *qemu_get_current_aio_context(void)
  36 {
  37     return my_iothread ? my_iothread->ctx : qemu_get_aio_context();
  38 }
  39
  40 static void *iothread_run(void *opaque)
  41 {
  42     IOThread *iothread = opaque;
  43
  44     rcu_register_thread();
  45
  46     my_iothread = iothread;
  47     qemu_mutex_lock(&iothread->init_done_lock);
  48     iothread->thread_id = qemu_get_thread_id();
  49     qemu_cond_signal(&iothread->init_done_cond);
  50     qemu_mutex_unlock(&iothread->init_done_lock);
  51
  52     while (!atomic_read(&iothread->stopping)) {
  53         aio_poll(iothread->ctx, true);
  54     }
  55
  56     rcu_unregister_thread();
  57     return NULL;
  58 }
  59
  60 static int iothread_stop(Object *object, void *opaque)
  61 {
  62     IOThread *iothread;
  63
  64     iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
  65     if (!iothread || !iothread->ctx) {
  66         return 0;
  67     }
  68     iothread->stopping = true;
  69     aio_notify(iothread->ctx);
  70     qemu_thread_join(&iothread->thread);
  71     return 0;
  72 }
  73
  74 static void iothread_instance_finalize(Object *obj)
  75 {
  76     IOThread *iothread = IOTHREAD(obj);
  77
  78     iothread_stop(obj, NULL);
  79     qemu_cond_destroy(&iothread->init_done_cond);
  80     qemu_mutex_destroy(&iothread->init_done_lock);
  81     if (!iothread->ctx) {
  82         return;
  83     }
  84     aio_context_unref(iothread->ctx);
  85 }
  86
  87 static void iothread_complete(UserCreatable *obj, Error **errp)
  88 {
  89     Error *local_error = NULL;
  90     IOThread *iothread = IOTHREAD(obj);
  91     char *name, *thread_name;
  92
  93     iothread->stopping = false;
  94     iothread->thread_id = -1;
  95     iothread->ctx = aio_context_new(&local_error);
  96     if (!iothread->ctx) {
  97         error_propagate(errp, local_error);
  98         return;
  99     }
 100
 101     aio_context_set_poll_params(iothread->ctx,
 102                                 iothread->poll_max_ns,
 103                                 iothread->poll_grow,
 104                                 iothread->poll_shrink,
 105                                 &local_error);
 106     if (local_error) {
 107         error_propagate(errp, local_error);
 108         aio_context_unref(iothread->ctx);
 109         iothread->ctx = NULL;
 110         return;
 111     }
 112
 113     qemu_mutex_init(&iothread->init_done_lock);
 114     qemu_cond_init(&iothread->init_done_cond);
 115
 116     /* This assumes we are called from a thread with useful CPU affinity for us
 117      * to inherit.
 118      */
 119     name = object_get_canonical_path_component(OBJECT(obj));
 120     thread_name = g_strdup_printf("IO %s", name);
 121     qemu_thread_create(&iothread->thread, thread_name, iothread_run,
 122                        iothread, QEMU_THREAD_JOINABLE);
 123     g_free(thread_name);
 124     g_free(name);
 125
 126     /* Wait for initialization to complete */
 127     qemu_mutex_lock(&iothread->init_done_lock);
 128     while (iothread->thread_id == -1) {
 129         qemu_cond_wait(&iothread->init_done_cond,
 130                        &iothread->init_done_lock);
 131     }
 132     qemu_mutex_unlock(&iothread->init_done_lock);
 133 }
 134
 135 typedef struct {
 136     const char *name;
 137     ptrdiff_t offset; /* field's byte offset in IOThread struct */
 138 } PollParamInfo;
 139
 140 static PollParamInfo poll_max_ns_info = {
 141     "poll-max-ns", offsetof(IOThread, poll_max_ns),
 142 };
 143 static PollParamInfo poll_grow_info = {
 144     "poll-grow", offsetof(IOThread, poll_grow),
 145 };
 146 static PollParamInfo poll_shrink_info = {
 147     "poll-shrink", offsetof(IOThread, poll_shrink),
 148 };
 149
 150 static void iothread_get_poll_param(Object *obj, Visitor *v,
 151         const char *name, void *opaque, Error **errp)
 152 {
 153     IOThread *iothread = IOTHREAD(obj);
 154     PollParamInfo *info = opaque;
 155     int64_t *field = (void *)iothread + info->offset;
 156
 157     visit_type_int64(v, name, field, errp);
 158 }
 159
 160 static void iothread_set_poll_param(Object *obj, Visitor *v,
 161         const char *name, void *opaque, Error **errp)
 162 {
 163     IOThread *iothread = IOTHREAD(obj);
 164     PollParamInfo *info = opaque;
 165     int64_t *field = (void *)iothread + info->offset;
 166     Error *local_err = NULL;
 167     int64_t value;
 168
 169     visit_type_int64(v, name, &value, &local_err);
 170     if (local_err) {
 171         goto out;
 172     }
 173
 174     if (value < 0) {
 175         error_setg(&local_err, "%s value must be in range [0, %"PRId64"]",
 176                    info->name, INT64_MAX);
 177         goto out;
 178     }
 179
 180     *field = value;
 181
 182     if (iothread->ctx) {
 183         aio_context_set_poll_params(iothread->ctx,
 184                                     iothread->poll_max_ns,
 185                                     iothread->poll_grow,
 186                                     iothread->poll_shrink,
 187                                     &local_err);
 188     }
 189
 190 out:
 191     error_propagate(errp, local_err);
 192 }
 193
 194 static void iothread_class_init(ObjectClass *klass, void *class_data)
 195 {
 196     UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
 197     ucc->complete = iothread_complete;
 198
 199     object_class_property_add(klass, "poll-max-ns", "int",
 200                               iothread_get_poll_param,
 201                               iothread_set_poll_param,
 202                               NULL, &poll_max_ns_info, &error_abort);
 203     object_class_property_add(klass, "poll-grow", "int",
 204                               iothread_get_poll_param,
 205                               iothread_set_poll_param,
 206                               NULL, &poll_grow_info, &error_abort);
 207     object_class_property_add(klass, "poll-shrink", "int",
 208                               iothread_get_poll_param,
 209                               iothread_set_poll_param,
 210                               NULL, &poll_shrink_info, &error_abort);
 211 }
 212
 213 static const TypeInfo iothread_info = {
 214     .name = TYPE_IOTHREAD,
 215     .parent = TYPE_OBJECT,
 216     .class_init = iothread_class_init,
 217     .instance_size = sizeof(IOThread),
 218     .instance_finalize = iothread_instance_finalize,
 219     .interfaces = (InterfaceInfo[]) {
 220         {TYPE_USER_CREATABLE},
 221         {}
 222     },
 223 };
 224
 225 static void iothread_register_types(void)
 226 {
 227     type_register_static(&iothread_info);
 228 }
 229
 230 type_init(iothread_register_types)
 231
 232 char *iothread_get_id(IOThread *iothread)
 233 {
 234     return object_get_canonical_path_component(OBJECT(iothread));
 235 }
 236
 237 AioContext *iothread_get_aio_context(IOThread *iothread)
 238 {
 239     return iothread->ctx;
 240 }
 241
 242 static int query_one_iothread(Object *object, void *opaque)
 243 {
 244     IOThreadInfoList ***prev = opaque;
 245     IOThreadInfoList *elem;
 246     IOThreadInfo *info;
 247     IOThread *iothread;
 248
 249     iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
 250     if (!iothread) {
 251         return 0;
 252     }
 253
 254     info = g_new0(IOThreadInfo, 1);
 255     info->id = iothread_get_id(iothread);
 256     info->thread_id = iothread->thread_id;
 257
 258     elem = g_new0(IOThreadInfoList, 1);
 259     elem->value = info;
 260     elem->next = NULL;
 261
 262     **prev = elem;
 263     *prev = &elem->next;
 264     return 0;
 265 }
 266
 267 IOThreadInfoList *qmp_query_iothreads(Error **errp)
 268 {
 269     IOThreadInfoList *head = NULL;
 270     IOThreadInfoList **prev = &head;
 271     Object *container = object_get_objects_root();
 272
 273     object_child_foreach(container, query_one_iothread, &prev);
 274     return head;
 275 }
 276
 277 void iothread_stop_all(void)
 278 {
 279     Object *container = object_get_objects_root();
 280     BlockDriverState *bs;
 281     BdrvNextIterator it;
 282
 283     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 284         AioContext *ctx = bdrv_get_aio_context(bs);
 285         if (ctx == qemu_get_aio_context()) {
 286             continue;
 287         }
 288         aio_context_acquire(ctx);
 289         bdrv_set_aio_context(bs, qemu_get_aio_context());
 290         aio_context_release(ctx);
 291     }
 292
 293     object_child_foreach(container, iothread_stop, NULL);
 294 }