Re: [dpdk-dev] [PATCH v3 5/6] ixgbe: Config VF RSS

["Ouyang, Changchun" <changchun.ouyang@intel.com>]

> -----Original Message-----
> From: Vlad Zolotarov [mailto:vladz@cloudius-systems.com]
> Sent: Thursday, December 25, 2014 9:39 PM
> To: Ouyang, Changchun; dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v3 5/6] ixgbe: Config VF RSS
> 
> 
> On 12/25/14 04:43, Ouyang, Changchun wrote:
> > Hi,
> > Sorry miss some comments, so continue my response below,
> >
> >> -----Original Message-----
> >> From: Vlad Zolotarov [mailto:vladz@cloudius-systems.com]
> >> Sent: Wednesday, December 24, 2014 6:40 PM
> >> To: Ouyang, Changchun; dev@dpdk.org
> >> Subject: Re: [dpdk-dev] [PATCH v3 5/6] ixgbe: Config VF RSS
> >>
> >>
> >> On 12/24/14 07:23, Ouyang Changchun wrote:
> >>> It needs config RSS and IXGBE_MRQC and IXGBE_VFPSRTYPE to enable
> VF
> >> RSS.
> >>> The psrtype will determine how many queues the received packets will
> >>> distribute to, and the value of psrtype should depends on both facet:
> >>> max VF rxq number which has been negotiated with PF, and the number
> >>> of
> >> rxq specified in config on guest.
> >>> Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
> >>> ---
> >>>    lib/librte_pmd_ixgbe/ixgbe_pf.c   | 15 +++++++
> >>>    lib/librte_pmd_ixgbe/ixgbe_rxtx.c | 92
> >> ++++++++++++++++++++++++++++++++++-----
> >>>    2 files changed, 97 insertions(+), 10 deletions(-)
> >>>
> >>> diff --git a/lib/librte_pmd_ixgbe/ixgbe_pf.c
> >>> b/lib/librte_pmd_ixgbe/ixgbe_pf.c index cbb0145..9c9dad8 100644
> >>> --- a/lib/librte_pmd_ixgbe/ixgbe_pf.c
> >>> +++ b/lib/librte_pmd_ixgbe/ixgbe_pf.c
> >>> @@ -187,6 +187,21 @@ int ixgbe_pf_host_configure(struct rte_eth_dev
> >> *eth_dev)
> >>>    	IXGBE_WRITE_REG(hw, IXGBE_MPSAR_LO(hw-
> mac.num_rar_entries), 0);
> >>>    	IXGBE_WRITE_REG(hw, IXGBE_MPSAR_HI(hw-
> mac.num_rar_entries), 0);
> >>>
> >>> +	/*
> >>> +	 * VF RSS can support at most 4 queues for each VF, even if
> >>> +	 * 8 queues are available for each VF, it need refine to 4
> >>> +	 * queues here due to this limitation, otherwise no queue
> >>> +	 * will receive any packet even RSS is enabled.
> >> According to Table 7-3 in the 82599 spec RSS is not available when
> >> port is configured to have 8 queues per pool. This means that if u
> >> see this configuration u may immediately disable RSS flow in your code.
> >>
> >>> +	 */
> >>> +	if (eth_dev->data->dev_conf.rxmode.mq_mode ==
> >> ETH_MQ_RX_VMDQ_RSS) {
> >>> +		if (RTE_ETH_DEV_SRIOV(eth_dev).nb_q_per_pool == 8) {
> >>> +			RTE_ETH_DEV_SRIOV(eth_dev).active =
> >> ETH_32_POOLS;
> >>> +			RTE_ETH_DEV_SRIOV(eth_dev).nb_q_per_pool = 4;
> >>> +			RTE_ETH_DEV_SRIOV(eth_dev).def_pool_q_idx =
> >>> +				dev_num_vf(eth_dev) * 4;
> >> According to 82599 spec u can't do that since RSS is not allowed when
> >> port is configured to have 8 function per-VF. Have u verified that
> >> this works? If yes, then spec should be updated.
> >>
> >>> +		}
> >>> +	}
> >>> +
> >>>    	/* set VMDq map to default PF pool */
> >>>    	hw->mac.ops.set_vmdq(hw, 0,
> >>> RTE_ETH_DEV_SRIOV(eth_dev).def_vmdq_idx);
> >>>
> >>> diff --git a/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> >>> b/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> >>> index f69abda..a7c17a4 100644
> >>> --- a/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> >>> +++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> >>> @@ -3327,6 +3327,39 @@ ixgbe_alloc_rx_queue_mbufs(struct
> >> igb_rx_queue *rxq)
> >>>    }
> >>>
> >>>    static int
> >>> +ixgbe_config_vf_rss(struct rte_eth_dev *dev) {
> >>> +	struct ixgbe_hw *hw;
> >>> +	uint32_t mrqc;
> >>> +
> >>> +	ixgbe_rss_configure(dev);
> >>> +
> >>> +	hw = IXGBE_DEV_PRIVATE_TO_HW(dev->data->dev_private);
> >>> +
> >>> +	/* MRQC: enable VF RSS */
> >>> +	mrqc = IXGBE_READ_REG(hw, IXGBE_MRQC);
> >>> +	mrqc &= ~IXGBE_MRQC_MRQE_MASK;
> >>> +	switch (RTE_ETH_DEV_SRIOV(dev).active) {
> >>> +	case ETH_64_POOLS:
> >>> +		mrqc |= IXGBE_MRQC_VMDQRSS64EN;
> >>> +		break;
> >>> +
> >>> +	case ETH_32_POOLS:
> >>> +	case ETH_16_POOLS:
> >>> +		mrqc |= IXGBE_MRQC_VMDQRSS32EN;
> >> Again, this contradicts with the spec.
> > Yes, the spec say the hw can't support vf rss at all, but experiment find that
> could be done.
> 
> I have just realized something - why did u have to experiment at all? U work
> at Intel, don't u? Can't u just ask a HW engineer that have designed this NIC?
> What do u mean by an "experiment" here?

HW and dpdk team are cross-geo and cross division, experiment is often needed
Because no spec, doc, discussion, meeting minutes is perfect and can include everything absolutely correct,
And don't miss one thing, are you agree?
  
Anyway Let's focus on technical question, please. 
 
>  From my experience u can't just write some random values in the registers

I don't think it is random data at all, do you see I use a random seed to generate a random data here?

> and conclude that if it worked for like 5 minutes it will continue to work for
> the next minute... There is always a clear procedure of how HW should be
> initialized and used and that's the only way it may be used since this was the
> way the HW has been tested. U can't assume anything in regards to reliability
> if u don't follow specs and programmer manuals of HW provider.
>
Sorry I don't think it doesn't follow spec and programmer manuals.
and if you have a bit bigger picture here(just mean the overall process for the vf rss enabling, and nothing else,
Don't think too much, hope it is clear), I am sure you won't get confused here.
Or my observation is you probably have another perfect solution to support vf rss in dpdk,
Right? If you have it, you could also submit your patch here, this is open source, I think you are free to do it.

> Could u clarify, please?
> 
> > We can focus on discussing the implementation firstly.
> >
> >>> +		break;
> >>> +
> >>> +	default:
> >>> +		PMD_INIT_LOG(ERR, "Invalid pool number in IOV mode");
> >>> +		return -EINVAL;
> >>> +	}
> >>> +
> >>> +	IXGBE_WRITE_REG(hw, IXGBE_MRQC, mrqc);
> >>> +
> >>> +	return 0;
> >>> +}
> >>> +
> >>> +static int
> >>>    ixgbe_dev_mq_rx_configure(struct rte_eth_dev *dev)
> >>>    {
> >>>    	struct ixgbe_hw *hw =
> >>> @@ -3358,24 +3391,38 @@ ixgbe_dev_mq_rx_configure(struct
> >> rte_eth_dev *dev)
> >>>    			default: ixgbe_rss_disable(dev);
> >>>    		}
> >>>    	} else {
> >>> -		switch (RTE_ETH_DEV_SRIOV(dev).active) {
> >>>    		/*
> >>>    		 * SRIOV active scheme
> >>>    		 * FIXME if support DCB/RSS together with VMDq & SRIOV
> >>>    		 */
> >>> -		case ETH_64_POOLS:
> >>> -			IXGBE_WRITE_REG(hw, IXGBE_MRQC,
> >> IXGBE_MRQC_VMDQEN);
> >>> +		switch (dev->data->dev_conf.rxmode.mq_mode) {
> >>> +		case ETH_MQ_RX_RSS:
> >>> +		case ETH_MQ_RX_VMDQ_RSS:
> >>> +			ixgbe_config_vf_rss(dev);
> >>>    			break;
> >>>
> >>> -		case ETH_32_POOLS:
> >>> -			IXGBE_WRITE_REG(hw, IXGBE_MRQC,
> >> IXGBE_MRQC_VMDQRT4TCEN);
> >>> -			break;
> >>> +		default:
> >>> +			switch (RTE_ETH_DEV_SRIOV(dev).active) {
> >> Sorry for nitpicking but have u considered taking this encapsulated
> >> "switch- case" block into a separate function? This could make the
> >> code look a lot nicer. ;)
> >>
> >>> +			case ETH_64_POOLS:
> >>> +				IXGBE_WRITE_REG(hw, IXGBE_MRQC,
> >>> +					IXGBE_MRQC_VMDQEN);
> >>> +				break;
> >>>
> >>> -		case ETH_16_POOLS:
> >>> -			IXGBE_WRITE_REG(hw, IXGBE_MRQC,
> >> IXGBE_MRQC_VMDQRT8TCEN);
> >>> +			case ETH_32_POOLS:
> >>> +				IXGBE_WRITE_REG(hw, IXGBE_MRQC,
> >>> +					IXGBE_MRQC_VMDQRT4TCEN);
> >>> +				break;
> >>> +
> >>> +			case ETH_16_POOLS:
> >>> +				IXGBE_WRITE_REG(hw, IXGBE_MRQC,
> >>> +					IXGBE_MRQC_VMDQRT8TCEN);
> >>> +				break;
> >>> +			default:
> >>> +				PMD_INIT_LOG(ERR,
> >>> +					"invalid pool number in IOV mode");
> >>> +				break;
> >>> +			}
> >>>    			break;
> >>> -		default:
> >>> -			PMD_INIT_LOG(ERR, "invalid pool number in IOV
> >> mode");
> >>>    		}
> >>>    	}
> >>>
> >>> @@ -3989,10 +4036,32 @@ ixgbevf_dev_rx_init(struct rte_eth_dev
> *dev)
> >>>    	uint16_t buf_size;
> >>>    	uint16_t i;
> >>>    	int ret;
> >>> +	uint16_t valid_rxq_num;
> >>>
> >>>    	PMD_INIT_FUNC_TRACE();
> >>>    	hw = IXGBE_DEV_PRIVATE_TO_HW(dev->data->dev_private);
> >>>
> >>> +	valid_rxq_num = RTE_MIN(dev->data->nb_rx_queues,
> >>> +hw->mac.max_rx_queues);
> >>> +
> >>> +	/*
> >>> +	 * VMDq RSS can't support 3 queues, so config it into 4 queues,
> >>> +	 * and give user a hint that some packets may loss if it doesn't
> >>> +	 * poll the queue where those packets are distributed to.
> >>> +	 */
> >>> +	if (valid_rxq_num == 3)
> >>> +		valid_rxq_num = 4;
> >> Why to configure more queues that requested and not less (2)? Why to
> >> configure anything at all and not return an error?
> > Sorry, I don't agree this is "anything" you say, because I don't use 5,6,7,
> 8, ..., 16, 2014, 2015,... etc.
> > By considering 2 or 4,
> > I prefer 4, the reason is if user need more than 3 queues per vf to do
> > something, And pf has also the capability to setup 4 queues per vf,
> > confining to 2 queues is also not good thing, So here try to enable 4 queues,
> and give user hints here.
> > Btw, change it into 2 is another way, depends on other guys' more insight
> here.
> >
> >>> +
> >>> +	if (dev->data->nb_rx_queues > valid_rxq_num) {
> >>> +		PMD_INIT_LOG(ERR, "The number of Rx queue invalid, "
> >>> +			"it should be equal to or less than %d",
> >>> +			valid_rxq_num);
> >>> +		return -1;
> >>> +	} else if (dev->data->nb_rx_queues < valid_rxq_num)
> >>> +		PMD_INIT_LOG(ERR, "The number of Rx queue is less "
> >>> +			"than the number of available Rx queues:%d, "
> >>> +			"packets in Rx queues(q_id >= %d) may loss.",
> >>> +			valid_rxq_num, dev->data->nb_rx_queues);
> >> Who ever looks in the "INIT_LOG" if everything "work well" and u make
> >> it look so by allowing this call to succeed. And then some packets
> >> will just silently not arrive?! And what the used should somehow guess to
> do?
> >> - Look in the "INIT_LOG"?! This is a nightmare!
> >>
> >>> +
> >>>    	/*
> >>>    	 * When the VF driver issues a IXGBE_VF_RESET request, the PF
> >> driver
> >>>    	 * disables the VF receipt of packets if the PF MTU is > 1500.
> >>> @@ -4094,6 +4163,9 @@ ixgbevf_dev_rx_init(struct rte_eth_dev *dev)
> >>>    			IXGBE_PSRTYPE_IPV6HDR;
> >>>    #endif
> >>>
> >>> +	/* Set RQPL for VF RSS according to max Rx queue */
> >>> +	psrtype |= (valid_rxq_num >> 1) <<
> >>> +		IXGBE_PSRTYPE_RQPL_SHIFT;
> >>>    	IXGBE_WRITE_REG(hw, IXGBE_VFPSRTYPE, psrtype);
> >>>
> >>>    	if (dev->data->dev_conf.rxmode.enable_scatter) {