Hi, Yuval
On 2017/9/26 14:43, Yuval Mintz wrote:
>> When using tc qdisc to configure DCB parameter, dcb_ops->setup_tc
>> is used to tell hclge_dcb module to do the setup.
>
> While this might be a step in the right direction, this causes an
> inconsistency
> in user experience - Some [well, most] vendors didn't allow the mqprio
> priority mapping to affect DCB, instead relying on the dcbnl functionality
> to control that configuration.
>
> A couple of options to consider:
> - Perhaps said logic shouldn't be contained inside the driver but rather
> in mqprio logic itself. I.e., rely on DCBNL functionality [if available]
> from
> within mqprio and try changing the configuration.
> - Add a new TC_MQPRIO_HW_OFFLOAD_ value to explicitly reflect user
> request to allow this configuration to affect DCB.
>
>> When using lldptool to configure DCB parameter, hclge_dcb module
>> call the client_ops->setup_tc to tell network stack which queue
>> and priority is using for specific tc.
>
> You're basically bypassing the mqprio logic.
> Since you're configuring the prio->queue mapping from DCB flow,
> you'll get an mqprio-like behavior [meaning a transmitted packet
> would reach a transmission queue associated with its priority] even
> if device wasn't grated with an mqprio qdisc.
> Why should your user even use mqprio? What benefit does he get from it?
When adding mqprio and lldptool support, I was thinking user can use
tc qdisc or lldptool to do the configuration, giving user two option to
setup the DCB.
If user is only tc qdisc or lldptool, I think there is no problem here.
when user is using tc qdisc and lldptool, As you explained above, When
tc qdisc changes the configuration, there should be a way to notify dcbnl,
so that the dcbnl can response correctly(like tell the peer it's configuration
has changed).
I will try to find if there is a way to do notify the dcbnl when using tc qdisc
to setup the configuration.
If there is not a way to do it now, then I will drop the mqprio in this patch,
and
will address this problem if there is need for the tc qdisc.
Please let me know if I was misunderstood.
And thanks for your time reviewing.
>
> ...
>
>> +static int hns3_nic_set_real_num_queue(struct net_device *netdev)
>> +{
>> + struct hns3_nic_priv *priv = netdev_priv(netdev);
>> + struct hnae3_handle *h = priv->ae_handle;
>> + struct hnae3_knic_private_info *kinfo = &h->kinfo;
>> + unsigned int queue_size = kinfo->rss_size * kinfo->num_tc;
>> + int ret;
>> +
>> + ret = netif_set_real_num_tx_queues(netdev, queue_size);
>> + if (ret) {
>> + netdev_err(netdev,
>> + "netif_set_real_num_tx_queues fail, ret=%d!\n",
>> + ret);
>> + return ret;
>> + }
>> +
>> + ret = netif_set_real_num_rx_queues(netdev, queue_size);
>
> I don't think you're changing the driver behavior, but why are you setting
> the real number of rx queues based on the number of TCs?
> Do you actually open (TC x RSS) Rx queues?
>
> .
>
