On Mon, Mar 20, 2023 at 01:49:30PM +0200, Eli Cohen wrote:
> One can still enable it when creating the vdpa device using vdpa tool by
> providing features that include it.
>
> For example:
> $ vdpa dev add name vdpa0 mgmtdev pci/0000:86:00.2 device_features 0x300cb982b
>
> Please be aware that this feature was not supported before the previous
> patch in this list was introduced so we don't change user experience.
so I would say the patches have to be reordered to avoid a regression?
> Current firmware versions show degradation in packet rate when using
> MRG_RXBUF. Users who favor memory saving over packet rate could enable
> this feature but we want to keep it off by default.
>
> Signed-off-by: Eli Cohen <elic@xxxxxxxxxx>
OK and when future firmware will (maybe) fix this up how
will you know it's ok to enable by default?
Some version check I guess?
It would be better if firmware specified flags to enable
by default ...
> ---
> drivers/vdpa/mlx5/net/mlx5_vnet.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index 5285dd76c793..24397a71d6f3 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -3146,6 +3146,8 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
> return -EINVAL;
> }
> device_features &= add_config->device_features;
> + } else {
> + device_features &= ~BIT_ULL(VIRTIO_NET_F_MRG_RXBUF);
> }
> if (!(device_features & BIT_ULL(VIRTIO_F_VERSION_1) &&
> device_features & BIT_ULL(VIRTIO_F_ACCESS_PLATFORM))) {
> --
> 2.38.1
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