mirror of
https://gitlab.com/qemu-project/qemu
synced 2024-09-06 09:55:55 +00:00
![Philippe Mathieu-Daudé](/assets/img/avatar_default.png)
aio_context_set_aio_params() doesn't use its undocumented Error** argument. Remove it to simplify. Note this removes a use of "unchecked Error**" in iothread_set_aio_context_params(). Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Message-ID: <20231120171806.19361-1-philmd@linaro.org>
410 lines
12 KiB
C
410 lines
12 KiB
C
/*
|
|
* Event loop thread
|
|
*
|
|
* Copyright Red Hat Inc., 2013, 2020
|
|
*
|
|
* Authors:
|
|
* Stefan Hajnoczi <stefanha@redhat.com>
|
|
*
|
|
* This work is licensed under the terms of the GNU GPL, version 2 or later.
|
|
* See the COPYING file in the top-level directory.
|
|
*
|
|
*/
|
|
|
|
#include "qemu/osdep.h"
|
|
#include "qom/object.h"
|
|
#include "qom/object_interfaces.h"
|
|
#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/error-report.h"
|
|
#include "qemu/rcu.h"
|
|
#include "qemu/main-loop.h"
|
|
|
|
|
|
#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
|
|
#else
|
|
#define IOTHREAD_POLL_MAX_NS_DEFAULT 0ULL
|
|
#endif
|
|
|
|
static void *iothread_run(void *opaque)
|
|
{
|
|
IOThread *iothread = opaque;
|
|
|
|
rcu_register_thread();
|
|
/*
|
|
* 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_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);
|
|
|
|
/*
|
|
* 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);
|
|
}
|
|
}
|
|
|
|
g_main_context_pop_thread_default(iothread->worker_context);
|
|
rcu_unregister_thread();
|
|
return NULL;
|
|
}
|
|
|
|
/* Runs in iothread_run() thread */
|
|
static void iothread_stop_bh(void *opaque)
|
|
{
|
|
IOThread *iothread = opaque;
|
|
|
|
iothread->running = false; /* stop iothread_run() */
|
|
|
|
if (iothread->main_loop) {
|
|
g_main_loop_quit(iothread->main_loop);
|
|
}
|
|
}
|
|
|
|
void iothread_stop(IOThread *iothread)
|
|
{
|
|
if (!iothread->ctx || iothread->stopping) {
|
|
return;
|
|
}
|
|
iothread->stopping = true;
|
|
aio_bh_schedule_oneshot(iothread->ctx, iothread_stop_bh, iothread);
|
|
qemu_thread_join(&iothread->thread);
|
|
}
|
|
|
|
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)
|
|
{
|
|
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_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_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_init(EventLoopBase *base, Error **errp)
|
|
{
|
|
Error *local_error = NULL;
|
|
IOThread *iothread = IOTHREAD(base);
|
|
g_autofree char *thread_name = NULL;
|
|
|
|
iothread->stopping = false;
|
|
iothread->running = true;
|
|
iothread->ctx = aio_context_new(errp);
|
|
if (!iothread->ctx) {
|
|
return;
|
|
}
|
|
|
|
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);
|
|
iothread->ctx = NULL;
|
|
return;
|
|
}
|
|
|
|
/* This assumes we are called from a thread with useful CPU affinity for us
|
|
* to inherit.
|
|
*/
|
|
qemu_thread_create(&iothread->thread, thread_name, iothread_run,
|
|
iothread, QEMU_THREAD_JOINABLE);
|
|
|
|
/* Wait for initialization to complete */
|
|
while (iothread->thread_id == -1) {
|
|
qemu_sem_wait(&iothread->init_done_sem);
|
|
}
|
|
}
|
|
|
|
typedef struct {
|
|
const char *name;
|
|
ptrdiff_t offset; /* field's byte offset in IOThread struct */
|
|
} IOThreadParamInfo;
|
|
|
|
static IOThreadParamInfo poll_max_ns_info = {
|
|
"poll-max-ns", offsetof(IOThread, poll_max_ns),
|
|
};
|
|
static IOThreadParamInfo poll_grow_info = {
|
|
"poll-grow", offsetof(IOThread, poll_grow),
|
|
};
|
|
static IOThreadParamInfo poll_shrink_info = {
|
|
"poll-shrink", offsetof(IOThread, poll_shrink),
|
|
};
|
|
|
|
static void iothread_get_param(Object *obj, Visitor *v,
|
|
const char *name, IOThreadParamInfo *info, Error **errp)
|
|
{
|
|
IOThread *iothread = IOTHREAD(obj);
|
|
int64_t *field = (void *)iothread + info->offset;
|
|
|
|
visit_type_int64(v, name, field, errp);
|
|
}
|
|
|
|
static bool iothread_set_param(Object *obj, Visitor *v,
|
|
const char *name, IOThreadParamInfo *info, Error **errp)
|
|
{
|
|
IOThread *iothread = IOTHREAD(obj);
|
|
int64_t *field = (void *)iothread + info->offset;
|
|
int64_t value;
|
|
|
|
if (!visit_type_int64(v, name, &value, errp)) {
|
|
return false;
|
|
}
|
|
|
|
if (value < 0) {
|
|
error_setg(errp, "%s value must be in range [0, %" PRId64 "]",
|
|
info->name, INT64_MAX);
|
|
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,
|
|
errp);
|
|
}
|
|
}
|
|
|
|
static void iothread_class_init(ObjectClass *klass, void *class_data)
|
|
{
|
|
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);
|
|
object_class_property_add(klass, "poll-grow", "int",
|
|
iothread_get_poll_param,
|
|
iothread_set_poll_param,
|
|
NULL, &poll_grow_info);
|
|
object_class_property_add(klass, "poll-shrink", "int",
|
|
iothread_get_poll_param,
|
|
iothread_set_poll_param,
|
|
NULL, &poll_shrink_info);
|
|
}
|
|
|
|
static const TypeInfo iothread_info = {
|
|
.name = TYPE_IOTHREAD,
|
|
.parent = TYPE_EVENT_LOOP_BASE,
|
|
.class_init = iothread_class_init,
|
|
.instance_size = sizeof(IOThread),
|
|
.instance_init = iothread_instance_init,
|
|
.instance_finalize = iothread_instance_finalize,
|
|
};
|
|
|
|
static void iothread_register_types(void)
|
|
{
|
|
type_register_static(&iothread_info);
|
|
}
|
|
|
|
type_init(iothread_register_types)
|
|
|
|
char *iothread_get_id(IOThread *iothread)
|
|
{
|
|
return g_strdup(object_get_canonical_path_component(OBJECT(iothread)));
|
|
}
|
|
|
|
AioContext *iothread_get_aio_context(IOThread *iothread)
|
|
{
|
|
return iothread->ctx;
|
|
}
|
|
|
|
static int query_one_iothread(Object *object, void *opaque)
|
|
{
|
|
IOThreadInfoList ***tail = opaque;
|
|
IOThreadInfo *info;
|
|
IOThread *iothread;
|
|
|
|
iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
|
|
if (!iothread) {
|
|
return 0;
|
|
}
|
|
|
|
info = g_new0(IOThreadInfo, 1);
|
|
info->id = iothread_get_id(iothread);
|
|
info->thread_id = iothread->thread_id;
|
|
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;
|
|
|
|
QAPI_LIST_APPEND(*tail, info);
|
|
return 0;
|
|
}
|
|
|
|
IOThreadInfoList *qmp_query_iothreads(Error **errp)
|
|
{
|
|
IOThreadInfoList *head = NULL;
|
|
IOThreadInfoList **prev = &head;
|
|
Object *container = object_get_objects_root();
|
|
|
|
object_child_foreach(container, query_one_iothread, &prev);
|
|
return head;
|
|
}
|
|
|
|
GMainContext *iothread_get_g_main_context(IOThread *iothread)
|
|
{
|
|
qatomic_set(&iothread->run_gcontext, 1);
|
|
aio_notify(iothread->ctx);
|
|
return iothread->worker_context;
|
|
}
|
|
|
|
IOThread *iothread_create(const char *id, Error **errp)
|
|
{
|
|
Object *obj;
|
|
|
|
obj = object_new_with_props(TYPE_IOTHREAD,
|
|
object_get_internal_root(),
|
|
id, errp, NULL);
|
|
|
|
return IOTHREAD(obj);
|
|
}
|
|
|
|
void iothread_destroy(IOThread *iothread)
|
|
{
|
|
object_unparent(OBJECT(iothread));
|
|
}
|
|
|
|
/* Lookup IOThread by its id. Only finds user-created objects, not internal
|
|
* iothread_create() objects. */
|
|
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() ?
|
|
false : true;
|
|
}
|