IOHandler *io_read;
IOHandler *io_write;
AioPollFn *io_poll;
+ IOHandler *io_poll_begin;
+ IOHandler *io_poll_end;
int deleted;
void *opaque;
bool is_external;
}
}
+void aio_set_fd_poll(AioContext *ctx, int fd,
+ IOHandler *io_poll_begin,
+ IOHandler *io_poll_end)
+{
+ AioHandler *node = find_aio_handler(ctx, fd);
+
+ if (!node) {
+ return;
+ }
+
+ node->io_poll_begin = io_poll_begin;
+ node->io_poll_end = io_poll_end;
+}
+
void aio_set_event_notifier(AioContext *ctx,
EventNotifier *notifier,
bool is_external,
(IOHandler *)io_read, NULL, io_poll, notifier);
}
+void aio_set_event_notifier_poll(AioContext *ctx,
+ EventNotifier *notifier,
+ EventNotifierHandler *io_poll_begin,
+ EventNotifierHandler *io_poll_end)
+{
+ aio_set_fd_poll(ctx, event_notifier_get_fd(notifier),
+ (IOHandler *)io_poll_begin,
+ (IOHandler *)io_poll_end);
+}
+
+static void poll_set_started(AioContext *ctx, bool started)
+{
+ AioHandler *node;
+
+ if (started == ctx->poll_started) {
+ return;
+ }
+
+ ctx->poll_started = started;
+
+ ctx->walking_handlers++;
+ QLIST_FOREACH(node, &ctx->aio_handlers, node) {
+ IOHandler *fn;
+
+ if (node->deleted) {
+ continue;
+ }
+
+ if (started) {
+ fn = node->io_poll_begin;
+ } else {
+ fn = node->io_poll_end;
+ }
+
+ if (fn) {
+ fn(node->opaque);
+ }
+ }
+ ctx->walking_handlers--;
+}
+
+
bool aio_prepare(AioContext *ctx)
{
+ /* Poll mode cannot be used with glib's event loop, disable it. */
+ poll_set_started(ctx, false);
+
return false;
}
npfd++;
}
+static bool run_poll_handlers_once(AioContext *ctx)
+{
+ bool progress = false;
+ AioHandler *node;
+
+ QLIST_FOREACH(node, &ctx->aio_handlers, node) {
+ if (!node->deleted && node->io_poll &&
+ node->io_poll(node->opaque)) {
+ progress = true;
+ }
+
+ /* Caller handles freeing deleted nodes. Don't do it here. */
+ }
+
+ return progress;
+}
+
/* run_poll_handlers:
* @ctx: the AioContext
* @max_ns: maximum time to poll for, in nanoseconds
*/
static bool run_poll_handlers(AioContext *ctx, int64_t max_ns)
{
- bool progress = false;
+ bool progress;
int64_t end_time;
assert(ctx->notify_me);
end_time = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + max_ns;
do {
- AioHandler *node;
-
- QLIST_FOREACH(node, &ctx->aio_handlers, node) {
- if (!node->deleted && node->io_poll &&
- node->io_poll(node->opaque)) {
- progress = true;
- }
-
- /* Caller handles freeing deleted nodes. Don't do it here. */
- }
+ progress = run_poll_handlers_once(ctx);
} while (!progress && qemu_clock_get_ns(QEMU_CLOCK_REALTIME) < end_time);
trace_run_poll_handlers_end(ctx, progress);
/* try_poll_mode:
* @ctx: the AioContext
- * @blocking: polling is only attempted when blocking is true
+ * @blocking: busy polling is only attempted when blocking is true
*
- * If blocking is true then ctx->notify_me must be non-zero so this function
- * can detect aio_notify().
+ * ctx->notify_me must be non-zero so this function can detect aio_notify().
*
* Note that the caller must have incremented ctx->walking_handlers.
*
if (blocking && ctx->poll_max_ns && ctx->poll_disable_cnt == 0) {
/* See qemu_soonest_timeout() uint64_t hack */
int64_t max_ns = MIN((uint64_t)aio_compute_timeout(ctx),
- (uint64_t)ctx->poll_max_ns);
+ (uint64_t)ctx->poll_ns);
if (max_ns) {
+ poll_set_started(ctx, true);
+
if (run_poll_handlers(ctx, max_ns)) {
return true;
}
}
}
- return false;
+ poll_set_started(ctx, false);
+
+ /* Even if we don't run busy polling, try polling once in case it can make
+ * progress and the caller will be able to avoid ppoll(2)/epoll_wait(2).
+ */
+ return run_poll_handlers_once(ctx);
}
bool aio_poll(AioContext *ctx, bool blocking)
int ret = 0;
bool progress;
int64_t timeout;
+ int64_t start = 0;
aio_context_acquire(ctx);
progress = false;
ctx->walking_handlers++;
+ if (ctx->poll_max_ns) {
+ start = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
+ }
+
if (try_poll_mode(ctx, blocking)) {
progress = true;
} else {
atomic_sub(&ctx->notify_me, 2);
}
+ /* Adjust polling time */
+ if (ctx->poll_max_ns) {
+ int64_t block_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start;
+
+ if (block_ns <= ctx->poll_ns) {
+ /* This is the sweet spot, no adjustment needed */
+ } else if (block_ns > ctx->poll_max_ns) {
+ /* We'd have to poll for too long, poll less */
+ int64_t old = ctx->poll_ns;
+
+ if (ctx->poll_shrink) {
+ ctx->poll_ns /= ctx->poll_shrink;
+ } else {
+ ctx->poll_ns = 0;
+ }
+
+ trace_poll_shrink(ctx, old, ctx->poll_ns);
+ } else if (ctx->poll_ns < ctx->poll_max_ns &&
+ block_ns < ctx->poll_max_ns) {
+ /* There is room to grow, poll longer */
+ int64_t old = ctx->poll_ns;
+ int64_t grow = ctx->poll_grow;
+
+ if (grow == 0) {
+ grow = 2;
+ }
+
+ if (ctx->poll_ns) {
+ ctx->poll_ns *= grow;
+ } else {
+ ctx->poll_ns = 4000; /* start polling at 4 microseconds */
+ }
+
+ if (ctx->poll_ns > ctx->poll_max_ns) {
+ ctx->poll_ns = ctx->poll_max_ns;
+ }
+
+ trace_poll_grow(ctx, old, ctx->poll_ns);
+ }
+ }
+
aio_notify_accept(ctx);
/* if we have any readable fds, dispatch event */
#endif
}
-void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns, Error **errp)
+void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,
+ int64_t grow, int64_t shrink, Error **errp)
{
- /* No thread synchronization here, it doesn't matter if an incorrect poll
- * timeout is used once.
+ /* No thread synchronization here, it doesn't matter if an incorrect value
+ * is used once.
*/
ctx->poll_max_ns = max_ns;
+ ctx->poll_ns = 0;
+ ctx->poll_grow = grow;
+ ctx->poll_shrink = shrink;
aio_notify(ctx);
}
projects / qemu.git / blobdiff