From a01a9cb821a29852abb142ec52b26c8488ced6e8 Mon Sep 17 00:00:00 2001 From: Amit Shah Date: Tue, 23 Nov 2010 17:01:15 +0530 Subject: [PATCH] virtio-serial-bus: bump up control vq size to 32 The current default of 16 buffers for the control vq is too small. We can get more entries in there, for example when asking the guest to add max. allowed ports. Note: a more robust solution would involve some kind of event queueing in host to guarantee no event loss. Added a TODO to look into this later. Signed-off-by: Amit Shah Signed-off-by: Michael S. Tsirkin --- hw/virtio-serial-bus.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c index 74ba5ec3d3..b728040f3a 100644 --- a/hw/virtio-serial-bus.c +++ b/hw/virtio-serial-bus.c @@ -769,10 +769,16 @@ VirtIODevice *virtio_serial_init(DeviceState *dev, uint32_t max_nr_ports) /* Add a queue for guest to host transfers for port 0 (backward compat) */ vser->ovqs[0] = virtio_add_queue(vdev, 128, handle_output); + /* TODO: host to guest notifications can get dropped + * if the queue fills up. Implement queueing in host, + * this might also make it possible to reduce the control + * queue size: as guest preposts buffers there, + * this will save 4Kbyte of guest memory per entry. */ + /* control queue: host to guest */ - vser->c_ivq = virtio_add_queue(vdev, 16, control_in); + vser->c_ivq = virtio_add_queue(vdev, 32, control_in); /* control queue: guest to host */ - vser->c_ovq = virtio_add_queue(vdev, 16, control_out); + vser->c_ovq = virtio_add_queue(vdev, 32, control_out); for (i = 1; i < vser->bus->max_nr_ports; i++) { /* Add a per-port queue for host to guest transfers */