mirror of https://gitee.com/openkylin/qemu.git
387 lines
11 KiB
C
387 lines
11 KiB
C
/*
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* Event loop thread
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*
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* Copyright Red Hat Inc., 2013
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*
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* Authors:
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* Stefan Hajnoczi <stefanha@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*
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*/
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#include "qemu/osdep.h"
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#include "qom/object.h"
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#include "qom/object_interfaces.h"
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#include "qemu/module.h"
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#include "block/aio.h"
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#include "block/block.h"
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#include "sysemu/iothread.h"
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#include "qapi/error.h"
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#include "qapi/qapi-commands-misc.h"
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#include "qemu/error-report.h"
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#include "qemu/rcu.h"
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#include "qemu/main-loop.h"
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typedef ObjectClass IOThreadClass;
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#define IOTHREAD_GET_CLASS(obj) \
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OBJECT_GET_CLASS(IOThreadClass, obj, TYPE_IOTHREAD)
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#define IOTHREAD_CLASS(klass) \
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OBJECT_CLASS_CHECK(IOThreadClass, klass, TYPE_IOTHREAD)
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#ifdef CONFIG_POSIX
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/* Benchmark results from 2016 on NVMe SSD drives show max polling times around
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* 16-32 microseconds yield IOPS improvements for both iodepth=1 and iodepth=32
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* workloads.
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*/
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#define IOTHREAD_POLL_MAX_NS_DEFAULT 32768ULL
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#else
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#define IOTHREAD_POLL_MAX_NS_DEFAULT 0ULL
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#endif
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static __thread IOThread *my_iothread;
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AioContext *qemu_get_current_aio_context(void)
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{
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return my_iothread ? my_iothread->ctx : qemu_get_aio_context();
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}
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static void *iothread_run(void *opaque)
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{
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IOThread *iothread = opaque;
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rcu_register_thread();
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my_iothread = iothread;
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qemu_mutex_lock(&iothread->init_done_lock);
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iothread->thread_id = qemu_get_thread_id();
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qemu_cond_signal(&iothread->init_done_cond);
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qemu_mutex_unlock(&iothread->init_done_lock);
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while (iothread->running) {
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aio_poll(iothread->ctx, true);
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if (atomic_read(&iothread->worker_context)) {
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GMainLoop *loop;
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g_main_context_push_thread_default(iothread->worker_context);
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iothread->main_loop =
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g_main_loop_new(iothread->worker_context, TRUE);
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loop = iothread->main_loop;
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g_main_loop_run(iothread->main_loop);
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iothread->main_loop = NULL;
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g_main_loop_unref(loop);
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g_main_context_pop_thread_default(iothread->worker_context);
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}
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}
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rcu_unregister_thread();
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return NULL;
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}
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/* Runs in iothread_run() thread */
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static void iothread_stop_bh(void *opaque)
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{
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IOThread *iothread = opaque;
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iothread->running = false; /* stop iothread_run() */
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if (iothread->main_loop) {
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g_main_loop_quit(iothread->main_loop);
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}
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}
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void iothread_stop(IOThread *iothread)
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{
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if (!iothread->ctx || iothread->stopping) {
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return;
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}
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iothread->stopping = true;
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aio_bh_schedule_oneshot(iothread->ctx, iothread_stop_bh, iothread);
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qemu_thread_join(&iothread->thread);
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}
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static void iothread_instance_init(Object *obj)
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{
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IOThread *iothread = IOTHREAD(obj);
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iothread->poll_max_ns = IOTHREAD_POLL_MAX_NS_DEFAULT;
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iothread->thread_id = -1;
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}
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static void iothread_instance_finalize(Object *obj)
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{
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IOThread *iothread = IOTHREAD(obj);
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iothread_stop(iothread);
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if (iothread->thread_id != -1) {
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qemu_cond_destroy(&iothread->init_done_cond);
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qemu_mutex_destroy(&iothread->init_done_lock);
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}
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/*
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* Before glib2 2.33.10, there is a glib2 bug that GSource context
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* pointer may not be cleared even if the context has already been
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* destroyed (while it should). Here let's free the AIO context
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* earlier to bypass that glib bug.
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*
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* We can remove this comment after the minimum supported glib2
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* version boosts to 2.33.10. Before that, let's free the
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* GSources first before destroying any GMainContext.
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*/
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if (iothread->ctx) {
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aio_context_unref(iothread->ctx);
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iothread->ctx = NULL;
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}
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if (iothread->worker_context) {
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g_main_context_unref(iothread->worker_context);
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iothread->worker_context = NULL;
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}
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}
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static void iothread_complete(UserCreatable *obj, Error **errp)
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{
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Error *local_error = NULL;
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IOThread *iothread = IOTHREAD(obj);
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char *name, *thread_name;
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iothread->stopping = false;
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iothread->running = true;
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iothread->ctx = aio_context_new(&local_error);
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if (!iothread->ctx) {
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error_propagate(errp, local_error);
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return;
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}
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aio_context_set_poll_params(iothread->ctx,
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iothread->poll_max_ns,
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iothread->poll_grow,
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iothread->poll_shrink,
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&local_error);
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if (local_error) {
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error_propagate(errp, local_error);
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aio_context_unref(iothread->ctx);
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iothread->ctx = NULL;
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return;
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}
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qemu_mutex_init(&iothread->init_done_lock);
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qemu_cond_init(&iothread->init_done_cond);
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iothread->once = (GOnce) G_ONCE_INIT;
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/* This assumes we are called from a thread with useful CPU affinity for us
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* to inherit.
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*/
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name = object_get_canonical_path_component(OBJECT(obj));
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thread_name = g_strdup_printf("IO %s", name);
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qemu_thread_create(&iothread->thread, thread_name, iothread_run,
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iothread, QEMU_THREAD_JOINABLE);
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g_free(thread_name);
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g_free(name);
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/* Wait for initialization to complete */
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qemu_mutex_lock(&iothread->init_done_lock);
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while (iothread->thread_id == -1) {
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qemu_cond_wait(&iothread->init_done_cond,
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&iothread->init_done_lock);
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}
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qemu_mutex_unlock(&iothread->init_done_lock);
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}
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typedef struct {
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const char *name;
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ptrdiff_t offset; /* field's byte offset in IOThread struct */
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} PollParamInfo;
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static PollParamInfo poll_max_ns_info = {
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"poll-max-ns", offsetof(IOThread, poll_max_ns),
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};
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static PollParamInfo poll_grow_info = {
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"poll-grow", offsetof(IOThread, poll_grow),
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};
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static PollParamInfo poll_shrink_info = {
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"poll-shrink", offsetof(IOThread, poll_shrink),
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};
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static void iothread_get_poll_param(Object *obj, Visitor *v,
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const char *name, void *opaque, Error **errp)
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{
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IOThread *iothread = IOTHREAD(obj);
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PollParamInfo *info = opaque;
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int64_t *field = (void *)iothread + info->offset;
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visit_type_int64(v, name, field, errp);
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}
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static void iothread_set_poll_param(Object *obj, Visitor *v,
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const char *name, void *opaque, Error **errp)
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{
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IOThread *iothread = IOTHREAD(obj);
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PollParamInfo *info = opaque;
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int64_t *field = (void *)iothread + info->offset;
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Error *local_err = NULL;
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int64_t value;
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visit_type_int64(v, name, &value, &local_err);
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if (local_err) {
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goto out;
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}
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if (value < 0) {
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error_setg(&local_err, "%s value must be in range [0, %"PRId64"]",
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info->name, INT64_MAX);
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goto out;
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}
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*field = value;
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if (iothread->ctx) {
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aio_context_set_poll_params(iothread->ctx,
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iothread->poll_max_ns,
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iothread->poll_grow,
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iothread->poll_shrink,
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&local_err);
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}
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out:
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error_propagate(errp, local_err);
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}
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static void iothread_class_init(ObjectClass *klass, void *class_data)
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{
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UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
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ucc->complete = iothread_complete;
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object_class_property_add(klass, "poll-max-ns", "int",
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iothread_get_poll_param,
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iothread_set_poll_param,
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NULL, &poll_max_ns_info, &error_abort);
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object_class_property_add(klass, "poll-grow", "int",
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iothread_get_poll_param,
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iothread_set_poll_param,
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NULL, &poll_grow_info, &error_abort);
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object_class_property_add(klass, "poll-shrink", "int",
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iothread_get_poll_param,
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iothread_set_poll_param,
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NULL, &poll_shrink_info, &error_abort);
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}
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static const TypeInfo iothread_info = {
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.name = TYPE_IOTHREAD,
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.parent = TYPE_OBJECT,
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.class_init = iothread_class_init,
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.instance_size = sizeof(IOThread),
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.instance_init = iothread_instance_init,
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.instance_finalize = iothread_instance_finalize,
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.interfaces = (InterfaceInfo[]) {
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{TYPE_USER_CREATABLE},
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{}
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},
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};
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static void iothread_register_types(void)
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{
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type_register_static(&iothread_info);
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}
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type_init(iothread_register_types)
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char *iothread_get_id(IOThread *iothread)
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{
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return object_get_canonical_path_component(OBJECT(iothread));
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}
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AioContext *iothread_get_aio_context(IOThread *iothread)
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{
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return iothread->ctx;
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}
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static int query_one_iothread(Object *object, void *opaque)
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{
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IOThreadInfoList ***prev = opaque;
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IOThreadInfoList *elem;
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IOThreadInfo *info;
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IOThread *iothread;
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iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
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if (!iothread) {
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return 0;
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}
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info = g_new0(IOThreadInfo, 1);
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info->id = iothread_get_id(iothread);
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info->thread_id = iothread->thread_id;
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info->poll_max_ns = iothread->poll_max_ns;
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info->poll_grow = iothread->poll_grow;
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info->poll_shrink = iothread->poll_shrink;
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elem = g_new0(IOThreadInfoList, 1);
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elem->value = info;
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elem->next = NULL;
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**prev = elem;
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*prev = &elem->next;
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return 0;
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}
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IOThreadInfoList *qmp_query_iothreads(Error **errp)
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{
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IOThreadInfoList *head = NULL;
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IOThreadInfoList **prev = &head;
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Object *container = object_get_objects_root();
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object_child_foreach(container, query_one_iothread, &prev);
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return head;
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}
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static gpointer iothread_g_main_context_init(gpointer opaque)
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{
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AioContext *ctx;
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IOThread *iothread = opaque;
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GSource *source;
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iothread->worker_context = g_main_context_new();
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ctx = iothread_get_aio_context(iothread);
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source = aio_get_g_source(ctx);
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g_source_attach(source, iothread->worker_context);
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g_source_unref(source);
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aio_notify(iothread->ctx);
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return NULL;
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}
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GMainContext *iothread_get_g_main_context(IOThread *iothread)
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{
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g_once(&iothread->once, iothread_g_main_context_init, iothread);
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return iothread->worker_context;
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}
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IOThread *iothread_create(const char *id, Error **errp)
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{
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Object *obj;
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obj = object_new_with_props(TYPE_IOTHREAD,
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object_get_internal_root(),
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id, errp, NULL);
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return IOTHREAD(obj);
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}
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void iothread_destroy(IOThread *iothread)
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{
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object_unparent(OBJECT(iothread));
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}
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/* Lookup IOThread by its id. Only finds user-created objects, not internal
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* iothread_create() objects. */
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IOThread *iothread_by_id(const char *id)
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{
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return IOTHREAD(object_resolve_path_type(id, TYPE_IOTHREAD, NULL));
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}
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