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| author | Stefan Hajnoczi <stefanha@redhat.com> | 2016-12-01 19:26:50 +0000 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2017-01-03 16:38:50 +0000 |
| commit | a7c8215e3bbcdd3b5dbaabfcecf236d4a9880558 (patch) | |
| tree | 055e226ce13776bee8762a93f36a31bb081fb31e | |
| parent | 684e508c23d28af8d6ed2c62738a0f60447c8274 (diff) | |
virtio: disable virtqueue notifications during polling
This is a performance optimization to eliminate vmexits during polling.
It also avoids spurious ioeventfd processing after polling ends.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20161201192652.9509-12-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
| -rw-r--r-- | hw/virtio/virtio.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 79b5c369a2..d40711a31d 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -2053,6 +2053,13 @@ static void virtio_queue_host_notifier_aio_read(EventNotifier *n) } } +static void virtio_queue_host_notifier_aio_poll_begin(EventNotifier *n) +{ + VirtQueue *vq = container_of(n, VirtQueue, host_notifier); + + virtio_queue_set_notification(vq, 0); +} + static bool virtio_queue_host_notifier_aio_poll(void *opaque) { EventNotifier *n = opaque; @@ -2066,6 +2073,14 @@ static bool virtio_queue_host_notifier_aio_poll(void *opaque) return true; } +static void virtio_queue_host_notifier_aio_poll_end(EventNotifier *n) +{ + VirtQueue *vq = container_of(n, VirtQueue, host_notifier); + + /* Caller polls once more after this to catch requests that race with us */ + virtio_queue_set_notification(vq, 1); +} + void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx, VirtIOHandleOutput handle_output) { @@ -2074,6 +2089,9 @@ void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx, aio_set_event_notifier(ctx, &vq->host_notifier, true, virtio_queue_host_notifier_aio_read, virtio_queue_host_notifier_aio_poll); + aio_set_event_notifier_poll(ctx, &vq->host_notifier, + virtio_queue_host_notifier_aio_poll_begin, + virtio_queue_host_notifier_aio_poll_end); } else { aio_set_event_notifier(ctx, &vq->host_notifier, true, NULL, NULL); /* Test and clear notifier before after disabling event, |