X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=iothread.c;h=7130be58e3e6c83640b7cf03b233c5069568e25b;hb=HEAD;hp=2ec5a3bffea4b8b4e493502970bf3471a80ad8be;hpb=4a22592e32868db846898831c27fbee8e73e24e3;p=mirror_qemu.git

diff --git a/iothread.c b/iothread.c
index 2ec5a3bffe..e1e9e04736 100644
--- a/iothread.c
+++ b/iothread.c
@@ -1,7 +1,7 @@
 /*
  * Event loop thread
  *
- * Copyright Red Hat Inc., 2013
+ * Copyright Red Hat Inc., 2013, 2020
  *
  * Authors:
  *  Stefan Hajnoczi   <stefanha@redhat.com>
@@ -17,6 +17,7 @@
 #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"
@@ -24,57 +25,53 @@
 #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
  * 16-32 microseconds yield IOPS improvements for both iodepth=1 and iodepth=32
  * workloads.
  */
 #define IOTHREAD_POLL_MAX_NS_DEFAULT 32768ULL
-
-static __thread IOThread *my_iothread;
-
-AioContext *qemu_get_current_aio_context(void)
-{
-    return my_iothread ? my_iothread->ctx : qemu_get_aio_context();
-}
+#else
+#define IOTHREAD_POLL_MAX_NS_DEFAULT 0ULL
+#endif
 
 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;
 }
@@ -101,23 +98,15 @@ void iothread_stop(IOThread *iothread)
     qemu_thread_join(&iothread->thread);
 }
 
-static int iothread_stop_iter(Object *object, void *opaque)
-{
-    IOThread *iothread;
-
-    iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
-    if (!iothread) {
-        return 0;
-    }
-    iothread_stop(iothread);
-    return 0;
-}
-
 static void iothread_instance_init(Object *obj)
 {
     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)
@@ -125,38 +114,92 @@ 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
+     * destroyed (while it should).  Here let's free the AIO context
+     * earlier to bypass that glib bug.
+     *
+     * We can remove this comment after the minimum supported glib2
+     * version boosts to 2.33.10.  Before that, let's free the
+     * GSources first before destroying any GMainContext.
+     */
+    if (iothread->ctx) {
+        aio_context_unref(iothread->ctx);
+        iothread->ctx = NULL;
+    }
     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_init_gcontext(IOThread *iothread, const char *thread_name)
+{
+    GSource *source;
+    g_autofree char *name = g_strdup_printf("%s aio-context", thread_name);
+
+    iothread->worker_context = g_main_context_new();
+    source = aio_get_g_source(iothread_get_aio_context(iothread));
+    g_source_set_name(source, name);
+    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);
+
     if (!iothread->ctx) {
         return;
     }
-    aio_context_unref(iothread->ctx);
+
+    aio_context_set_poll_params(iothread->ctx,
+                                iothread->poll_max_ns,
+                                iothread->poll_grow,
+                                iothread->poll_shrink,
+                                errp);
+    if (*errp) {
+        return;
+    }
+
+    aio_context_set_aio_params(iothread->ctx,
+                               iothread->parent_obj.aio_max_batch);
+
+    aio_context_set_thread_pool_params(iothread->ctx, base->thread_pool_min,
+                                       base->thread_pool_max, errp);
 }
 
-static void iothread_complete(UserCreatable *obj, Error **errp)
+
+static void iothread_init(EventLoopBase *base, Error **errp)
 {
     Error *local_error = NULL;
-    IOThread *iothread = IOTHREAD(obj);
-    char *name, *thread_name;
+    IOThread *iothread = IOTHREAD(base);
+    g_autofree char *thread_name = NULL;
 
     iothread->stopping = false;
     iothread->running = true;
-    iothread->thread_id = -1;
-    iothread->ctx = aio_context_new(&local_error);
+    iothread->ctx = aio_context_new(errp);
     if (!iothread->ctx) {
-        error_propagate(errp, local_error);
         return;
     }
 
-    aio_context_set_poll_params(iothread->ctx,
-                                iothread->poll_max_ns,
-                                iothread->poll_grow,
-                                iothread->poll_shrink,
-                                &local_error);
+    thread_name = g_strdup_printf("IO %s",
+                        object_get_canonical_path_component(OBJECT(base)));
+
+    /*
+     * Init one GMainContext for the iothread unconditionally, even if
+     * it's not used
+     */
+    iothread_init_gcontext(iothread, thread_name);
+
+    iothread_set_aio_context_params(base, &local_error);
     if (local_error) {
         error_propagate(errp, local_error);
         aio_context_unref(iothread->ctx);
@@ -164,118 +207,119 @@ static void iothread_complete(UserCreatable *obj, Error **errp)
         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);
     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)
@@ -287,7 +331,7 @@ type_init(iothread_register_types)
 
 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)
@@ -297,8 +341,7 @@ 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;
 
@@ -313,13 +356,9 @@ static int query_one_iothread(Object *object, void *opaque)
     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;
 }
 
@@ -333,46 +372,10 @@ IOThreadInfoList *qmp_query_iothreads(Error **errp)
     return head;
 }
 
-void iothread_stop_all(void)
-{
-    Object *container = object_get_objects_root();
-    BlockDriverState *bs;
-    BdrvNextIterator it;
-
-    for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
-        AioContext *ctx = bdrv_get_aio_context(bs);
-        if (ctx == qemu_get_aio_context()) {
-            continue;
-        }
-        aio_context_acquire(ctx);
-        bdrv_set_aio_context(bs, qemu_get_aio_context());
-        aio_context_release(ctx);
-    }
-
-    object_child_foreach(container, iothread_stop_iter, NULL);
-}
-
-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;
 }
 
@@ -398,3 +401,8 @@ IOThread *iothread_by_id(const char *id)
 {
     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();
+}