diff --git a/aio-posix.c b/aio-posix.c
index 5216d82290f96125c4737c997963facbb4ee9820..15855715d45a254d6287cffb7447f63b250a73d4 100644
--- a/aio-posix.c
+++ b/aio-posix.c
@@ -550,7 +550,7 @@ static bool try_poll_mode(AioContext *ctx, bool blocking)
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);
@@ -576,6 +576,7 @@ 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;
@@ -593,6 +594,10 @@ bool aio_poll(AioContext *ctx, bool blocking)
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 {
@@ -635,6 +640,47 @@ bool aio_poll(AioContext *ctx, bool blocking)
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 */
@@ -678,12 +724,16 @@ void aio_context_setup(AioContext *ctx)
#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);
}
diff --git a/aio-win32.c b/aio-win32.c
index d0e40a854c1088c7c9ffc16fb6647e8236464175..d19dc429d8d4c3a3db797c487ef00d302efe47e6 100644
--- a/aio-win32.c
+++ b/aio-win32.c
@@ -395,7 +395,8 @@ void aio_context_setup(AioContext *ctx)
{
}
-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)
{
error_setg(errp, "AioContext polling is not implemented on Windows");
}
diff --git a/async.c b/async.c
index 29abf40ca737652ee89077f323f8044ac3b59245..29601718345c4136ac99c51077c446e7fb17d0c8 100644
--- a/async.c
+++ b/async.c
@@ -385,7 +385,10 @@ AioContext *aio_context_new(Error **errp)
qemu_rec_mutex_init(&ctx->lock);
timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
+ ctx->poll_ns = 0;
ctx->poll_max_ns = 0;
+ ctx->poll_grow = 0;
+ ctx->poll_shrink = 0;
return ctx;
fail:
diff --git a/include/block/aio.h b/include/block/aio.h
index 3817d179fd04275a87e3092a84fe1a09c22f5688..4dca54d9c7e3eecad17fdc76e8d9e1bcaf336b29 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -134,8 +134,11 @@ struct AioContext {
/* Number of AioHandlers without .io_poll() */
int poll_disable_cnt;
- /* Maximum polling time in nanoseconds */
- int64_t poll_max_ns;
+ /* Polling mode parameters */
+ int64_t poll_ns; /* current polling time in nanoseconds */
+ int64_t poll_max_ns; /* maximum polling time in nanoseconds */
+ int64_t poll_grow; /* polling time growth factor */
+ int64_t poll_shrink; /* polling time shrink factor */
/* Are we in polling mode or monitoring file descriptors? */
bool poll_started;
@@ -511,10 +514,13 @@ void aio_context_setup(AioContext *ctx);
* aio_context_set_poll_params:
* @ctx: the aio context
* @max_ns: how long to busy poll for, in nanoseconds
+ * @grow: polling time growth factor
+ * @shrink: polling time shrink factor
*
* Poll mode can be disabled by setting poll_max_ns to 0.
*/
void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,
+ int64_t grow, int64_t shrink,
Error **errp);
#endif
diff --git a/iothread.c b/iothread.c
index 8dfd10dee6ca7cdf2847ed47bd3c3291441f14e7..28598b5463fd25d2bab3bb308aa99a093054adb1 100644
--- a/iothread.c
+++ b/iothread.c
@@ -98,7 +98,7 @@ static void iothread_complete(UserCreatable *obj, Error **errp)
return;
}
- aio_context_set_poll_params(iothread->ctx, iothread->poll_max_ns,
+ aio_context_set_poll_params(iothread->ctx, iothread->poll_max_ns, 0, 0,
&local_error);
if (local_error) {
error_propagate(errp, local_error);
@@ -158,7 +158,7 @@ static void iothread_set_poll_max_ns(Object *obj, Visitor *v,
iothread->poll_max_ns = value;
if (iothread->ctx) {
- aio_context_set_poll_params(iothread->ctx, value, &local_err);
+ aio_context_set_poll_params(iothread->ctx, value, 0, 0, &local_err);
}
out:
diff --git a/trace-events b/trace-events
index 7fe3a1b0e8ffef0783a41ca51c4633b2b9105971..11814864545fd04b458ce1bab059434bcd932e12 100644
--- a/trace-events
+++ b/trace-events
@@ -28,6 +28,8 @@
# aio-posix.c
run_poll_handlers_begin(void *ctx, int64_t max_ns) "ctx %p max_ns %"PRId64
run_poll_handlers_end(void *ctx, bool progress) "ctx %p progress %d"
+poll_shrink(void *ctx, int64_t old, int64_t new) "ctx %p old %"PRId64" new %"PRId64
+poll_grow(void *ctx, int64_t old, int64_t new) "ctx %p old %"PRId64" new %"PRId64
# thread-pool.c
thread_pool_submit(void *pool, void *req, void *opaque) "pool %p req %p opaque %p"