[dpdk-dev] [PATCH v2] net/ixgbe: support multiqueue mode VMDq DCB with SRIOV

[Iremonger, Bernard]

Hi Wenzhuo,

<snip>

> > Subject: RE: [PATCH v2] net/ixgbe: support multiqueue mode VMDq DCB
> > with SRIOV
> >
> > Hi Wenzhuo,
> >
> > > >  	if (hw->mac.type != ixgbe_mac_82598EB) { @@ -3339,11 +3340,17
> > > @@
> > > > ixgbe_dcb_tx_hw_config(struct ixgbe_hw *hw,
> > > >  		if (dcb_config->vt_mode)
> > > >  			reg |= IXGBE_MTQC_VT_ENA;
> > > >  		IXGBE_WRITE_REG(hw, IXGBE_MTQC, reg);
> > > > -
> > > > -		/* Disable drop for all queues */
> > > > -		for (q = 0; q < 128; q++)
> > > > -			IXGBE_WRITE_REG(hw, IXGBE_QDE,
> > > > -				(IXGBE_QDE_WRITE | (q <<
> > > > IXGBE_QDE_IDX_SHIFT)));
> > > > +		if (RTE_ETH_DEV_SRIOV(dev).active == 0) {
> > > > +			/* Disable drop for all queues in VMDQ mode*/
> > > > +			for (q = 0; q < 128; q++)
> > > > +				IXGBE_WRITE_REG(hw, IXGBE_QDE,
> > > > +						(IXGBE_QDE_WRITE | (q <<
> > > > IXGBE_QDE_IDX_SHIFT) | IXGBE_QDE_ENABLE));
> > > > +		} else {
> > > > +			/* Enable drop for all queues in SRIOV mode */
> > > > +			for (q = 0; q < 128; q++)
> > > > +				IXGBE_WRITE_REG(hw, IXGBE_QDE,
> > > > +						(IXGBE_QDE_WRITE | (q <<
> > > > IXGBE_QDE_IDX_SHIFT)));
> > > > +		}
> > > I think it has nothing to do with mq mode. Do I miss something?
> >
> > Behavior is different when SRIOV is enabled.
> I don't understand why the behavior is different. To my opinion, the drop
> has nothing to do with the mode. We can enable or disable it.
> The old behavior is disabling it by default. Now you change it to disabling it by
> default in NO-SRIOV mode, but enabling it in SRIOV mode.
> What I don't get is the reason.

Please refer to section 4.6.11.3.1 page 180 of the 82599-10-gbe-controller-datasheet.pdf
The last paragraph on page 180 states:

"Queue Drop Enable (PFQDE) - In SR-IO the QDE bit should be set to 1b in the PFQDE register for all queues.
In VMDq mode, the QDE bit should be set to 0b for all queues."
 

> > > >  		/* Enable the Tx desc arbiter */
> > > >  		reg = IXGBE_READ_REG(hw, IXGBE_RTTDCS); @@ -3378,7
> > > > +3385,7 @@ ixgbe_vmdq_dcb_hw_tx_config(struct rte_eth_dev *dev,
> > > >  			vmdq_tx_conf->nb_queue_pools == ETH_16_POOLS
> > > ?
> > > > 0xFFFF : 0xFFFFFFFF);
> > > >
> > > >  	/*Configure general DCB TX parameters*/
> > > > -	ixgbe_dcb_tx_hw_config(hw, dcb_config);
> > > > +	ixgbe_dcb_tx_hw_config(dev, dcb_config);
> > > >  }
> > > >
> > > >  static void
> > > > @@ -3661,7 +3668,7 @@ ixgbe_dcb_hw_configure(struct rte_eth_dev
> > > *dev,
> > > >  		/*get DCB TX configuration parameters from rte_eth_conf*/
> > > >  		ixgbe_dcb_tx_config(dev, dcb_config);
> > > >  		/*Configure general DCB TX parameters*/
> > > > -		ixgbe_dcb_tx_hw_config(hw, dcb_config);
> > > > +		ixgbe_dcb_tx_hw_config(dev, dcb_config);
> > > >  		break;
> > > >  	default:
> > > >  		PMD_INIT_LOG(ERR, "Incorrect DCB TX mode
> > > configuration"); @@
> > > > -3810,9 +3817,6 @@ void ixgbe_configure_dcb(struct rte_eth_dev
> *dev)
> > > >  	    (dev_conf->rxmode.mq_mode != ETH_MQ_RX_DCB_RSS))
> > > >  		return;
> > > >
> > > > -	if (dev->data->nb_rx_queues != ETH_DCB_NUM_QUEUES)
> > > > -		return;
> > > I remember it's a limitation of implementation. The reason is the
> > > resource allocation. Why could we remove it now?
> >
> > ETH_DCB_NUM_QUEUES is 128,  nb_rx_queues may not be 128.
> I think it's a limitation to force the queue number to be
> ETH_DCB_NUM_QUEUES.
> Just to confirm it, have you try to set rx queue number to something
> different from 128, like 64, 32...

In my test scenario the nb_rx_queues is 1.

Regards,

Bernard