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

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

On Mon, Feb 03, 2020 at 03:17:07PM +0300, Denis Plotnikov wrote:
> 
> 
> On 30.01.2020 16:38, Michael S. Tsirkin wrote:
> > 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.
> Ok, then let's just make a separate queue length constant for each type.

it's just a number, I don't think we need a constant here.
If you feel it needs documentation, add a comment!

> (Will redo and send in the next series)
> Thanks!
> 
> Denis
> > 
> > > ---
> > >   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