From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=57167 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PPxuE-0000NT-Ll for qemu-devel@nongnu.org; Tue, 07 Dec 2010 08:48:35 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PPxuD-0005St-J3 for qemu-devel@nongnu.org; Tue, 07 Dec 2010 08:48:34 -0500 Received: from mx1.redhat.com ([209.132.183.28]:10171) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PPxuD-0005Sd-9y for qemu-devel@nongnu.org; Tue, 07 Dec 2010 08:48:33 -0500 From: Amit Shah Date: Tue, 7 Dec 2010 19:18:21 +0530 Message-Id: <82f9bcb012f3ea49f0d58b0daadfa1dcdfc1c20d.1291729697.git.amit.shah@redhat.com> Subject: [Qemu-devel] [[PATCH][RESEND]] virtio-serial-bus: Bump up control vq descriptors to min. required List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu list Cc: Amit Shah The current default of 16 buffers for the control vq is too small for the default max_nr_ports of 32. We can get more entries in there, example when asking the guest to add max. allowed ports. Default to using the minimum required (next power of 2) of the max_nr_ports in use. Signed-off-by: Amit Shah --- hw/virtio-serial-bus.c | 13 ++++++++++--- 1 files changed, 10 insertions(+), 3 deletions(-) diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c index 74ba5ec..eb7b362 100644 --- a/hw/virtio-serial-bus.c +++ b/hw/virtio-serial-bus.c @@ -736,7 +736,7 @@ VirtIODevice *virtio_serial_init(DeviceState *dev, uint32_t max_nr_ports) { VirtIOSerial *vser; VirtIODevice *vdev; - uint32_t i, max_supported_ports; + uint32_t i, max_supported_ports, cvq_len; if (!max_nr_ports) return NULL; @@ -769,10 +769,17 @@ 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); + /* + * The number of descriptors to use should always be a power of + * two. Use the next power of 2 of max_nr_ports to keep the + * entries to a minimum. + */ + cvq_len = 1 << qemu_fls(max_nr_ports - 1); + /* control queue: host to guest */ - vser->c_ivq = virtio_add_queue(vdev, 16, control_in); + vser->c_ivq = virtio_add_queue(vdev, cvq_len, control_in); /* control queue: guest to host */ - vser->c_ovq = virtio_add_queue(vdev, 16, control_out); + vser->c_ovq = virtio_add_queue(vdev, cvq_len, control_out); for (i = 1; i < vser->bus->max_nr_ports; i++) { /* Add a per-port queue for host to guest transfers */ -- 1.7.3.2