Re: [PATCH v1 1/4] virtio: introduce VIRTQUEUE_DEFUALT_SIZE instead of hardcoded constants

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Jan 29, 2020 at 05:06:59PM +0300, Denis Plotnikov wrote:
> Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>


I'm not sure what the point is. It's more or less an accident that
these two devices share the queue size, this constance
makes no sense to me.

> ---
>  hw/block/virtio-blk.c      | 6 ++++--
>  hw/scsi/virtio-scsi.c      | 5 +++--
>  include/hw/virtio/virtio.h | 1 +
>  3 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> index 09f46ed85f..72f935033f 100644
> --- a/hw/block/virtio-blk.c
> +++ b/hw/block/virtio-blk.c
> @@ -914,7 +914,8 @@ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config)
>      memset(&blkcfg, 0, sizeof(blkcfg));
>      virtio_stq_p(vdev, &blkcfg.capacity, capacity);
>      virtio_stl_p(vdev, &blkcfg.seg_max,
> -                 s->conf.seg_max_adjust ? s->conf.queue_size - 2 : 128 - 2);
> +                 s->conf.seg_max_adjust ? s->conf.queue_size - 2 :
> +                                          VIRTQUEUE_DEFAULT_SIZE - 2);
>      virtio_stw_p(vdev, &blkcfg.geometry.cylinders, conf->cyls);
>      virtio_stl_p(vdev, &blkcfg.blk_size, blk_size);
>      virtio_stw_p(vdev, &blkcfg.min_io_size, conf->min_io_size / blk_size);
> @@ -1272,7 +1273,8 @@ static Property virtio_blk_properties[] = {
>      DEFINE_PROP_BIT("request-merging", VirtIOBlock, conf.request_merging, 0,
>                      true),
>      DEFINE_PROP_UINT16("num-queues", VirtIOBlock, conf.num_queues, 1),
> -    DEFINE_PROP_UINT16("queue-size", VirtIOBlock, conf.queue_size, 128),
> +    DEFINE_PROP_UINT16("queue-size", VirtIOBlock, conf.queue_size,
> +                       VIRTQUEUE_DEFAULT_SIZE),
>      DEFINE_PROP_BOOL("seg-max-adjust", VirtIOBlock, conf.seg_max_adjust, true),
>      DEFINE_PROP_LINK("iothread", VirtIOBlock, conf.iothread, TYPE_IOTHREAD,
>                       IOThread *),
> diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
> index 3b61563609..36f66046ae 100644
> --- a/hw/scsi/virtio-scsi.c
> +++ b/hw/scsi/virtio-scsi.c
> @@ -660,7 +660,8 @@ static void virtio_scsi_get_config(VirtIODevice *vdev,
>  
>      virtio_stl_p(vdev, &scsiconf->num_queues, s->conf.num_queues);
>      virtio_stl_p(vdev, &scsiconf->seg_max,
> -                 s->conf.seg_max_adjust ? s->conf.virtqueue_size - 2 : 128 - 2);
> +                 s->conf.seg_max_adjust ? s->conf.virtqueue_size - 2 :
> +                                          VIRTQUEUE_DEFAULT_SIZE - 2);
>      virtio_stl_p(vdev, &scsiconf->max_sectors, s->conf.max_sectors);
>      virtio_stl_p(vdev, &scsiconf->cmd_per_lun, s->conf.cmd_per_lun);
>      virtio_stl_p(vdev, &scsiconf->event_info_size, sizeof(VirtIOSCSIEvent));
> @@ -965,7 +966,7 @@ static void virtio_scsi_device_unrealize(DeviceState *dev, Error **errp)
>  static Property virtio_scsi_properties[] = {
>      DEFINE_PROP_UINT32("num_queues", VirtIOSCSI, parent_obj.conf.num_queues, 1),
>      DEFINE_PROP_UINT32("virtqueue_size", VirtIOSCSI,
> -                                         parent_obj.conf.virtqueue_size, 128),
> +                       parent_obj.conf.virtqueue_size, VIRTQUEUE_DEFAULT_SIZE),
>      DEFINE_PROP_BOOL("seg_max_adjust", VirtIOSCSI,
>                        parent_obj.conf.seg_max_adjust, true),
>      DEFINE_PROP_UINT32("max_sectors", VirtIOSCSI, parent_obj.conf.max_sectors,
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index b69d517496..a66ea2368b 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -48,6 +48,7 @@ size_t virtio_feature_get_config_size(VirtIOFeature *features,
>  typedef struct VirtQueue VirtQueue;
>  
>  #define VIRTQUEUE_MAX_SIZE 1024
> +#define VIRTQUEUE_DEFAULT_SIZE 128
>  
>  typedef struct VirtQueueElement
>  {
> -- 
> 2.17.0