/*
* Event loop thread
*
- * Copyright Red Hat Inc., 2013
+ * Copyright Red Hat Inc., 2013, 2020
*
* Authors:
* Stefan Hajnoczi <stefanha@redhat.com>
#include "qemu/module.h"
#include "block/aio.h"
#include "block/block.h"
+#include "sysemu/event-loop-base.h"
#include "sysemu/iothread.h"
#include "qapi/error.h"
#include "qapi/qapi-commands-misc.h"
#include "qemu/rcu.h"
#include "qemu/main-loop.h"
-typedef ObjectClass IOThreadClass;
-
-#define IOTHREAD_GET_CLASS(obj) \
- OBJECT_GET_CLASS(IOThreadClass, obj, TYPE_IOTHREAD)
-#define IOTHREAD_CLASS(klass) \
- OBJECT_CLASS_CHECK(IOThreadClass, klass, TYPE_IOTHREAD)
#ifdef CONFIG_POSIX
/* Benchmark results from 2016 on NVMe SSD drives show max polling times around
#define IOTHREAD_POLL_MAX_NS_DEFAULT 0ULL
#endif
-static __thread IOThread *my_iothread;
-
-AioContext *qemu_get_current_aio_context(void)
-{
- return my_iothread ? my_iothread->ctx : qemu_get_aio_context();
-}
-
static void *iothread_run(void *opaque)
{
IOThread *iothread = opaque;
rcu_register_thread();
-
- my_iothread = iothread;
- qemu_mutex_lock(&iothread->init_done_lock);
+ /*
+ * g_main_context_push_thread_default() must be called before anything
+ * in this new thread uses glib.
+ */
+ g_main_context_push_thread_default(iothread->worker_context);
+ qemu_set_current_aio_context(iothread->ctx);
iothread->thread_id = qemu_get_thread_id();
- qemu_cond_signal(&iothread->init_done_cond);
- qemu_mutex_unlock(&iothread->init_done_lock);
+ qemu_sem_post(&iothread->init_done_sem);
while (iothread->running) {
+ /*
+ * Note: from functional-wise the g_main_loop_run() below can
+ * already cover the aio_poll() events, but we can't run the
+ * main loop unconditionally because explicit aio_poll() here
+ * is faster than g_main_loop_run() when we do not need the
+ * gcontext at all (e.g., pure block layer iothreads). In
+ * other words, when we want to run the gcontext with the
+ * iothread we need to pay some performance for functionality.
+ */
aio_poll(iothread->ctx, true);
- if (atomic_read(&iothread->worker_context)) {
- GMainLoop *loop;
-
- g_main_context_push_thread_default(iothread->worker_context);
- iothread->main_loop =
- g_main_loop_new(iothread->worker_context, TRUE);
- loop = iothread->main_loop;
-
+ /*
+ * We must check the running state again in case it was
+ * changed in previous aio_poll()
+ */
+ if (iothread->running && qatomic_read(&iothread->run_gcontext)) {
g_main_loop_run(iothread->main_loop);
- iothread->main_loop = NULL;
- g_main_loop_unref(loop);
-
- g_main_context_pop_thread_default(iothread->worker_context);
}
}
+ g_main_context_pop_thread_default(iothread->worker_context);
rcu_unregister_thread();
return NULL;
}
IOThread *iothread = IOTHREAD(obj);
iothread->poll_max_ns = IOTHREAD_POLL_MAX_NS_DEFAULT;
+ iothread->thread_id = -1;
+ qemu_sem_init(&iothread->init_done_sem, 0);
+ /* By default, we don't run gcontext */
+ qatomic_set(&iothread->run_gcontext, 0);
}
static void iothread_instance_finalize(Object *obj)
IOThread *iothread = IOTHREAD(obj);
iothread_stop(iothread);
+
/*
* Before glib2 2.33.10, there is a glib2 bug that GSource context
* pointer may not be cleared even if the context has already been
if (iothread->worker_context) {
g_main_context_unref(iothread->worker_context);
iothread->worker_context = NULL;
+ g_main_loop_unref(iothread->main_loop);
+ iothread->main_loop = NULL;
}
- qemu_cond_destroy(&iothread->init_done_cond);
- qemu_mutex_destroy(&iothread->init_done_lock);
+ qemu_sem_destroy(&iothread->init_done_sem);
}
-static void iothread_complete(UserCreatable *obj, Error **errp)
+static void iothread_init_gcontext(IOThread *iothread)
{
- Error *local_error = NULL;
- IOThread *iothread = IOTHREAD(obj);
- char *name, *thread_name;
+ GSource *source;
+
+ iothread->worker_context = g_main_context_new();
+ source = aio_get_g_source(iothread_get_aio_context(iothread));
+ g_source_attach(source, iothread->worker_context);
+ g_source_unref(source);
+ iothread->main_loop = g_main_loop_new(iothread->worker_context, TRUE);
+}
+
+static void iothread_set_aio_context_params(EventLoopBase *base, Error **errp)
+{
+ ERRP_GUARD();
+ IOThread *iothread = IOTHREAD(base);
- iothread->stopping = false;
- iothread->running = true;
- iothread->thread_id = -1;
- iothread->ctx = aio_context_new(&local_error);
if (!iothread->ctx) {
- error_propagate(errp, local_error);
return;
}
iothread->poll_max_ns,
iothread->poll_grow,
iothread->poll_shrink,
- &local_error);
+ errp);
+ if (*errp) {
+ return;
+ }
+
+ aio_context_set_aio_params(iothread->ctx,
+ iothread->parent_obj.aio_max_batch,
+ errp);
+
+ aio_context_set_thread_pool_params(iothread->ctx, base->thread_pool_min,
+ base->thread_pool_max, errp);
+}
+
+
+static void iothread_init(EventLoopBase *base, Error **errp)
+{
+ Error *local_error = NULL;
+ IOThread *iothread = IOTHREAD(base);
+ char *thread_name;
+
+ iothread->stopping = false;
+ iothread->running = true;
+ iothread->ctx = aio_context_new(errp);
+ if (!iothread->ctx) {
+ return;
+ }
+
+ /*
+ * Init one GMainContext for the iothread unconditionally, even if
+ * it's not used
+ */
+ iothread_init_gcontext(iothread);
+
+ iothread_set_aio_context_params(base, &local_error);
if (local_error) {
error_propagate(errp, local_error);
aio_context_unref(iothread->ctx);
return;
}
- qemu_mutex_init(&iothread->init_done_lock);
- qemu_cond_init(&iothread->init_done_cond);
- iothread->once = (GOnce) G_ONCE_INIT;
-
/* This assumes we are called from a thread with useful CPU affinity for us
* to inherit.
*/
- name = object_get_canonical_path_component(OBJECT(obj));
- thread_name = g_strdup_printf("IO %s", name);
+ thread_name = g_strdup_printf("IO %s",
+ object_get_canonical_path_component(OBJECT(base)));
qemu_thread_create(&iothread->thread, thread_name, iothread_run,
iothread, QEMU_THREAD_JOINABLE);
g_free(thread_name);
- g_free(name);
/* Wait for initialization to complete */
- qemu_mutex_lock(&iothread->init_done_lock);
while (iothread->thread_id == -1) {
- qemu_cond_wait(&iothread->init_done_cond,
- &iothread->init_done_lock);
+ qemu_sem_wait(&iothread->init_done_sem);
}
- qemu_mutex_unlock(&iothread->init_done_lock);
}
typedef struct {
const char *name;
ptrdiff_t offset; /* field's byte offset in IOThread struct */
-} PollParamInfo;
+} IOThreadParamInfo;
-static PollParamInfo poll_max_ns_info = {
+static IOThreadParamInfo poll_max_ns_info = {
"poll-max-ns", offsetof(IOThread, poll_max_ns),
};
-static PollParamInfo poll_grow_info = {
+static IOThreadParamInfo poll_grow_info = {
"poll-grow", offsetof(IOThread, poll_grow),
};
-static PollParamInfo poll_shrink_info = {
+static IOThreadParamInfo poll_shrink_info = {
"poll-shrink", offsetof(IOThread, poll_shrink),
};
-static void iothread_get_poll_param(Object *obj, Visitor *v,
- const char *name, void *opaque, Error **errp)
+static void iothread_get_param(Object *obj, Visitor *v,
+ const char *name, IOThreadParamInfo *info, Error **errp)
{
IOThread *iothread = IOTHREAD(obj);
- PollParamInfo *info = opaque;
int64_t *field = (void *)iothread + info->offset;
visit_type_int64(v, name, field, errp);
}
-static void iothread_set_poll_param(Object *obj, Visitor *v,
- const char *name, void *opaque, Error **errp)
+static bool iothread_set_param(Object *obj, Visitor *v,
+ const char *name, IOThreadParamInfo *info, Error **errp)
{
IOThread *iothread = IOTHREAD(obj);
- PollParamInfo *info = opaque;
int64_t *field = (void *)iothread + info->offset;
- Error *local_err = NULL;
int64_t value;
- visit_type_int64(v, name, &value, &local_err);
- if (local_err) {
- goto out;
+ if (!visit_type_int64(v, name, &value, errp)) {
+ return false;
}
if (value < 0) {
- error_setg(&local_err, "%s value must be in range [0, %"PRId64"]",
+ error_setg(errp, "%s value must be in range [0, %" PRId64 "]",
info->name, INT64_MAX);
- goto out;
+ return false;
}
*field = value;
+ return true;
+}
+
+static void iothread_get_poll_param(Object *obj, Visitor *v,
+ const char *name, void *opaque, Error **errp)
+{
+ IOThreadParamInfo *info = opaque;
+
+ iothread_get_param(obj, v, name, info, errp);
+}
+
+static void iothread_set_poll_param(Object *obj, Visitor *v,
+ const char *name, void *opaque, Error **errp)
+{
+ IOThread *iothread = IOTHREAD(obj);
+ IOThreadParamInfo *info = opaque;
+
+ if (!iothread_set_param(obj, v, name, info, errp)) {
+ return;
+ }
+
if (iothread->ctx) {
aio_context_set_poll_params(iothread->ctx,
iothread->poll_max_ns,
iothread->poll_grow,
iothread->poll_shrink,
- &local_err);
+ errp);
}
-
-out:
- error_propagate(errp, local_err);
}
static void iothread_class_init(ObjectClass *klass, void *class_data)
{
- UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
- ucc->complete = iothread_complete;
+ EventLoopBaseClass *bc = EVENT_LOOP_BASE_CLASS(klass);
+
+ bc->init = iothread_init;
+ bc->update_params = iothread_set_aio_context_params;
object_class_property_add(klass, "poll-max-ns", "int",
iothread_get_poll_param,
iothread_set_poll_param,
- NULL, &poll_max_ns_info, &error_abort);
+ NULL, &poll_max_ns_info);
object_class_property_add(klass, "poll-grow", "int",
iothread_get_poll_param,
iothread_set_poll_param,
- NULL, &poll_grow_info, &error_abort);
+ NULL, &poll_grow_info);
object_class_property_add(klass, "poll-shrink", "int",
iothread_get_poll_param,
iothread_set_poll_param,
- NULL, &poll_shrink_info, &error_abort);
+ NULL, &poll_shrink_info);
}
static const TypeInfo iothread_info = {
.name = TYPE_IOTHREAD,
- .parent = TYPE_OBJECT,
+ .parent = TYPE_EVENT_LOOP_BASE,
.class_init = iothread_class_init,
.instance_size = sizeof(IOThread),
.instance_init = iothread_instance_init,
.instance_finalize = iothread_instance_finalize,
- .interfaces = (InterfaceInfo[]) {
- {TYPE_USER_CREATABLE},
- {}
- },
};
static void iothread_register_types(void)
char *iothread_get_id(IOThread *iothread)
{
- return object_get_canonical_path_component(OBJECT(iothread));
+ return g_strdup(object_get_canonical_path_component(OBJECT(iothread)));
}
AioContext *iothread_get_aio_context(IOThread *iothread)
static int query_one_iothread(Object *object, void *opaque)
{
- IOThreadInfoList ***prev = opaque;
- IOThreadInfoList *elem;
+ IOThreadInfoList ***tail = opaque;
IOThreadInfo *info;
IOThread *iothread;
info->poll_max_ns = iothread->poll_max_ns;
info->poll_grow = iothread->poll_grow;
info->poll_shrink = iothread->poll_shrink;
+ info->aio_max_batch = iothread->parent_obj.aio_max_batch;
- elem = g_new0(IOThreadInfoList, 1);
- elem->value = info;
- elem->next = NULL;
-
- **prev = elem;
- *prev = &elem->next;
+ QAPI_LIST_APPEND(*tail, info);
return 0;
}
return head;
}
-static gpointer iothread_g_main_context_init(gpointer opaque)
-{
- AioContext *ctx;
- IOThread *iothread = opaque;
- GSource *source;
-
- iothread->worker_context = g_main_context_new();
-
- ctx = iothread_get_aio_context(iothread);
- source = aio_get_g_source(ctx);
- g_source_attach(source, iothread->worker_context);
- g_source_unref(source);
-
- aio_notify(iothread->ctx);
- return NULL;
-}
-
GMainContext *iothread_get_g_main_context(IOThread *iothread)
{
- g_once(&iothread->once, iothread_g_main_context_init, iothread);
-
+ qatomic_set(&iothread->run_gcontext, 1);
+ aio_notify(iothread->ctx);
return iothread->worker_context;
}
{
return IOTHREAD(object_resolve_path_type(id, TYPE_IOTHREAD, NULL));
}
+
+bool qemu_in_iothread(void)
+{
+ return qemu_get_current_aio_context() == qemu_get_aio_context() ?
+ false : true;
+}