Re: [dpdk-dev] [PATCH v4 4/6] ether: Check VMDq RSS mode

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

> -----Original Message-----
> From: Vlad Zolotarov [mailto:vladz@cloudius-systems.com]
> Sent: Wednesday, January 7, 2015 3:56 AM
> To: Ouyang, Changchun; dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v4 4/6] ether: Check VMDq RSS mode
> 
> 
> On 01/06/15 03:56, Ouyang, Changchun wrote:
> >> -----Original Message-----
> >> From: Vlad Zolotarov [mailto:vladz@cloudius-systems.com]
> >> Sent: Monday, January 5, 2015 6:10 PM
> >> To: Ouyang, Changchun;dev@dpdk.org
> >> Subject: Re: [dpdk-dev] [PATCH v4 4/6] ether: Check VMDq RSS mode
> >>
> >>
> >> On 01/05/15 03:00, Ouyang, Changchun wrote:
> >>>> -----Original Message-----
> >>>> From: Vlad Zolotarov [mailto:vladz@cloudius-systems.com]
> >>>> Sent: Sunday, January 4, 2015 5:46 PM
> >>>> To: Ouyang, Changchun;dev@dpdk.org
> >>>> Subject: Re: [dpdk-dev] [PATCH v4 4/6] ether: Check VMDq RSS mode
> >>>>
> >>>>
> >>>> On 01/04/15 10:58, Ouyang, Changchun wrote:
> >>>>>> -----Original Message-----
> >>>>>> From: Vlad Zolotarov [mailto:vladz@cloudius-systems.com]
> >>>>>> Sent: Sunday, January 4, 2015 4:45 PM
> >>>>>> To: Ouyang, Changchun;dev@dpdk.org
> >>>>>> Subject: Re: [dpdk-dev] [PATCH v4 4/6] ether: Check VMDq RSS
> mode
> >>>>>>
> >>>>>>
> >>>>>> On 01/04/15 09:18, Ouyang Changchun wrote:
> >>>>>>> Check mq mode for VMDq RSS, handle it correctly instead of
> >>>>>>> returning an error; Also remove the limitation of per pool queue
> >>>>>>> number has max value of 1, because the per pool queue number
> >> could
> >>>>>>> be 2 or 4 if it is VMDq RSS mode;
> >>>>>>>
> >>>>>>> The number of rxq specified in config will determine the mq mode
> >>>>>>> for
> >>>>>> VMDq RSS.
> >>>>>>> Signed-off-by: Changchun Ouyang<changchun.ouyang@intel.com>
> >>>>>>> ---
> >>>>>>>      lib/librte_ether/rte_ethdev.c | 39
> >>>>>> ++++++++++++++++++++++++++++++++++-----
> >>>>>>>      1 file changed, 34 insertions(+), 5 deletions(-)
> >>>>>>>
> >>>>>>> diff --git a/lib/librte_ether/rte_ethdev.c
> >>>>>>> b/lib/librte_ether/rte_ethdev.c index 95f2ceb..59ff325 100644
> >>>>>>> --- a/lib/librte_ether/rte_ethdev.c
> >>>>>>> +++ b/lib/librte_ether/rte_ethdev.c
> >>>>>>> @@ -510,8 +510,7 @@ rte_eth_dev_check_mq_mode(uint8_t
> >> port_id,
> >>>>>>> uint16_t nb_rx_q, uint16_t nb_tx_q,
> >>>>>>>
> >>>>>>>      	if (RTE_ETH_DEV_SRIOV(dev).active != 0) {
> >>>>>>>      		/* check multi-queue mode */
> >>>>>>> -		if ((dev_conf->rxmode.mq_mode ==
> >> ETH_MQ_RX_RSS) ||
> >>>>>>> -		    (dev_conf->rxmode.mq_mode ==
> >> ETH_MQ_RX_DCB) ||
> >>>>>>> +		if ((dev_conf->rxmode.mq_mode ==
> >> ETH_MQ_RX_DCB) ||
> >>>>>>>      		    (dev_conf->rxmode.mq_mode ==
> >> ETH_MQ_RX_DCB_RSS)
> >>>>>> ||
> >>>>>>>      		    (dev_conf->txmode.mq_mode ==
> >> ETH_MQ_TX_DCB)) {
> >>>>>>>      			/* SRIOV only works in VMDq enable mode
> >> */ @@ -
> >>>>>> 525,7 +524,6 @@
> >>>>>>> rte_eth_dev_check_mq_mode(uint8_t port_id, uint16_t nb_rx_q,
> >>>>>> uint16_t nb_tx_q,
> >>>>>>>      		}
> >>>>>>>
> >>>>>>>      		switch (dev_conf->rxmode.mq_mode) {
> >>>>>>> -		case ETH_MQ_RX_VMDQ_RSS:
> >>>>>>>      		case ETH_MQ_RX_VMDQ_DCB:
> >>>>>>>      		case ETH_MQ_RX_VMDQ_DCB_RSS:
> >>>>>>>      			/* DCB/RSS VMDQ in SRIOV mode, not
> >> implement
> >>>>>> yet */ @@ -534,6
> >>>>>>> +532,39 @@ rte_eth_dev_check_mq_mode(uint8_t port_id,
> uint16_t
> >>>>>> nb_rx_q, uint16_t nb_tx_q,
> >>>>>>>      					"unsupported VMDQ
> >> mq_mode
> >>>>>> rx %u\n",
> >>>>>>>      					port_id, dev_conf-
> >>>>>>> rxmode.mq_mode);
> >>>>>>>      			return (-EINVAL);
> >>>>>>> +		case ETH_MQ_RX_RSS:
> >>>>>>> +			PMD_DEBUG_TRACE("ethdev port_id=%"
> >> PRIu8
> >>>>>>> +					" SRIOV active, "
> >>>>>>> +					"Rx mq mode is changed
> >> from:"
> >>>>>>> +					"mq_mode %u into VMDQ
> >>>>>> mq_mode %u\n",
> >>>>>>> +					port_id,
> >>>>>>> +					dev_conf-
> >>> rxmode.mq_mode,
> >>>>>>> +					dev->data-
> >>>>>>> dev_conf.rxmode.mq_mode);
> >>>>>>> +		case ETH_MQ_RX_VMDQ_RSS:
> >>>>>>> +			dev->data->dev_conf.rxmode.mq_mode =
> >>>>>> ETH_MQ_RX_VMDQ_RSS;
> >>>>>>> +			if (nb_rx_q <
> >>>>>> RTE_ETH_DEV_SRIOV(dev).nb_q_per_pool) {
> >>>> Missed that before: shouldn't it be "<=" here?
> >>> Agree with you, need <= here, I will fix it in v5
> >>>
> >>>>>>> +				switch (nb_rx_q) {
> >>>>>>> +				case 1:
> >>>>>>> +				case 2:
> >>>>>>> +
> >> 	RTE_ETH_DEV_SRIOV(dev).active =
> >>>>>>> +						ETH_64_POOLS;
> >>>>>>> +					break;
> >>>>>>> +				case 4:
> >>>>>>> +
> >> 	RTE_ETH_DEV_SRIOV(dev).active =
> >>>>>>> +						ETH_32_POOLS;
> >>>>>>> +					break;
> >>>>>>> +				default:
> >>>>>>> +
> >> 	PMD_DEBUG_TRACE("ethdev
> >>>>>> port_id=%d"
> >>>>>>> +						" SRIOV active, "
> >>>>>>> +						"queue number
> >> invalid\n",
> >>>>>>> +						port_id);
> >>>>>>> +					return -EINVAL;
> >>>>>>> +				}
> >>>>>>> +
> >> 	RTE_ETH_DEV_SRIOV(dev).nb_q_per_pool =
> >>>>>> nb_rx_q;
> >>>>>>> +
> >> 	RTE_ETH_DEV_SRIOV(dev).def_pool_q_idx =
> >>>>>>> +					dev->pci_dev->max_vfs *
> >> nb_rx_q;
> >>>>>>> +			}
> >>>>>> Don't u need to return an error in the "else" here?
> >>>>> Actually it has such a check after these code snippet, and it does
> >>>>> return error for the else case, Because it is original logic, I
> >>>>> don't change any
> >>>> code around it, so it doesn't display here, you can check the codes.
> >>>>
> >>>> I see. The flow is a bit confusing since the switch-case above will
> >>>> end up executing a "default" clause which will set
> >>>> RTE_ETH_DEV_SRIOV(dev).nb_q_per_pool to 1 and then the error
> >> message
> >>>> in the check u are referring will be a bit confusing.
> >>> ' set RTE_ETH_DEV_SRIOV(dev).nb_q_per_pool to 1 ' is original code,
> >> which is for vmdq only case, or single queue case.
> >>> It is in default clause, and not in VMDQ_RSS clause.
> >>> I think my new code is ok here.
> >> The original code is ok and your current code will work. The only
> >> problem with your new code is that in case on an error like I've
> >> described above the error message will be confusing.
> > Then what's your suggestion for the better log message?  I can consider
> refine it if you have better one.
> 
> Just like I've suggested before - u may break with appropriate error message
> right when u see the problem (in a "else" clause). This way the code will be
> both more readable and more robust and won't break if anybody decides to
> change the not-RSS-specific logic u r relying on.

Well, it couldn't be done so easily, I think,  the test condition is:
if (nb_rx_q <= RTE_ETH_DEV_SRIOV(dev).nb_q_per_pool),  
so the else clause is the case of nb_rx_q > RTE_ETH_DEV_SRIOV(dev).nb_q_per_pool,
its functionality is comparing nb_rx_q and RTE_ETH_DEV_SRIOV(dev).nb_q_per_pool,

but the switch case will further confine nb_rx_q to 1 or 2 or 4 on the condition of it passes the above test,

and also there are codes refine the RTE_ETH_DEV_SRIOV(dev).nb_q_per_pool etc.

just changing the return into break, will break the logic, 
e.g.
when  nb_rx_q is 8, and RTE_ETH_DEV_SRIOV(dev).nb_q_per_pool is 8,
the test pass, and go into default branch,
it just print some message and break, 
continue refining(but nothing changed this time),
then check valid queue number a few lines below, this time it fail the test, because 
nb_rx_q == rather than >  RTE_ETH_DEV_SRIOV(dev).nb_q_per_pool , so it doesn't print err mesge and don't return the -EINVAL.

Then the behavior is not expected.

From other hand,
The reason why I have not the else branch for the test nb_rx_q <= RTE_ETH_DEV_SRIOV(dev).nb_q_per_pool,
It  is because there is same check below itself, and just don't want the duplicated check for the same thing

> >>>>> Thanks
> >>>>> Changchun
> >>>>>
> >>>>>