Re: [dpdk-dev] [PATCH] net/ixgbe: fix reconfiguration of rx queues

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> -----Original Message-----
> From: Ananyev, Konstantin
> Sent: Monday, January 29, 2018 5:51 PM
> To: Ananyev, Konstantin <konstantin.ananyev@intel.com>
> Subject: [PATCH] net/ixgbe: fix reconfiguration of rx queues
> 
> 
> 
> From: Chas Williams [mailto:3chas3@gmail.com]
> Sent: Monday, January 29, 2018 4:49 PM
> To: Ananyev, Konstantin <konstantin.ananyev@intel.com>
> Cc: dev@dpdk.org; Lu, Wenzhuo <wenzhuo.lu@intel.com>; Charles (Chas) Williams <chas3@att.com>
> Subject: Re: [PATCH] net/ixgbe: fix reconfiguration of rx queues
> 
> 
> 
> On Mon, Jan 29, 2018 at 11:25 AM, Ananyev, Konstantin <konstantin.ananyev@intel.com> wrote:
> 
> > -----Original Message-----
> > From: Chas Williams [mailto:3chas3@gmail.com]
> > Sent: Monday, January 29, 2018 3:21 PM
> > To: dev@dpdk.org
> > Cc: Lu, Wenzhuo <wenzhuo.lu@intel.com>; Ananyev, Konstantin <konstantin.ananyev@intel.com>; Charles (Chas) Williams
> > <chas3@att.com>
> > Subject: [PATCH] net/ixgbe: fix reconfiguration of rx queues
> >
> > From: "Charles (Chas) Williams" <chas3@att.com>
> >
> > .dev_configure() may be called again after RX queues have been setup.
> > This has the effect of clearing whatever setting the RX queues made for
> > rx_bulk_alloc_allowed or rx_vec_allowed.  Only reset this configuration
> > is there aren't any currently allocated queues.
> >
> > Fixes: 01fa1d6215fa ("ixgbe: unify Rx setup")
> >
> > Signed-off-by: Chas Williams <chas3@att.com>
> > ---
> >  drivers/net/ixgbe/ixgbe_ethdev.c | 18 ++++++++++++++++--
> >  1 file changed, 16 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/ixgbe/ixgbe_ethdev.c b/drivers/net/ixgbe/ixgbe_ethdev.c
> > index 37eb668..b39249a 100644
> > --- a/drivers/net/ixgbe/ixgbe_ethdev.c
> > +++ b/drivers/net/ixgbe/ixgbe_ethdev.c
> > @@ -2348,6 +2348,7 @@ ixgbe_dev_configure(struct rte_eth_dev *dev)
> >       struct ixgbe_adapter *adapter =
> >               (struct ixgbe_adapter *)dev->data->dev_private;
> >       int ret;
> > +     uint16_t i;
> >
> >       PMD_INIT_FUNC_TRACE();
> >       /* multipe queue mode checking */
> > @@ -2363,11 +2364,17 @@ ixgbe_dev_configure(struct rte_eth_dev *dev)
> >
> >       /*
> >        * Initialize to TRUE. If any of Rx queues doesn't meet the bulk
> > -      * allocation or vector Rx preconditions we will reset it.
> > +      * allocation or vector Rx preconditions we will reset it. We
> > +      * can only do this is there aren't any existing RX queues.
> >        */
> > +     for (i = 0; i < dev->data->nb_rx_queues; i++) {
> > +             if (dev->data->rx_queues[i])
> > +                     goto out;
> > +     }
> I don't see why this is needed.
> It surely should be possible to reconfigure device with different
> number of queues.
> Konstantin
> 
> Yes, you can add new queues but you shouldn't reset the bulk and vec settings
> that have already been chosen by the previously allocated queues. 

Why is that? Might be in new queue setup user will change settings?

> If those queues
> set rx_bulk_alloc_allowed to be false, then this is going to cause an issue with queue
> release later on.  

Could you be a bit more specific here:
What you think will be broken in ixgbe_rx_queue_release() in that case?

> This breaks:
> 
> rte_eth_dev_configure(..., 1, 1, ...);
> rx_queue_setup(1)
>    [rx_queue_setup decides that it can't support rx_bulk_alloc_allowed]
> ..
> 
> Later, you want to add some more queues,  you call
> 
> eth_eth_dev_configure(..., 2, 2, ...);

After you call dev_configure, you'll have to do queue_setup() for all your queues.
dev_configure() can changes some global device settings, so each queue has to be
reconfigured. 
In your example It should be:
eth_eth_dev_configure(..., 2, 2, ...);
rx_queue_setup(...,0, ...);
rx_queue_setup(...,1, ...);

Konstantin

> rx_queue_setup(2)
>   [rx_queue_setup hopefully makes the same choice as rxqid = 1?]
> ...
> 
> Is one supposed to release all queues before calling rte_eth_dev_configure()? If
> that is true, it seems like the change_mtu examples I see are possibly wrong.  As
> suggested in kenrel_nic_interface.rst:
> 
> 
>         ret = rte_eth_dev_configure(port_id, 1, 1, &conf);
>         if (ret < 0) {
>             RTE_LOG(ERR, APP, "Fail to reconfigure port %d\n", port_id);
>             return ret;
>         }
> 
>         /* Restart specific port */
> 
>         ret = rte_eth_dev_start(port_id);
>         if (ret < 0) {
>              RTE_LOG(ERR, APP, "Fail to restart port %d\n", port_id);
>             return ret;
>         }
> 
> This is will obviously reset the rx_bulk_alloc_allowed and not reallocated the RX queues.
> 
> 
> >       adapter->rx_bulk_alloc_allowed = true;
> >       adapter->rx_vec_allowed = true;
> >
> > +out:
> >       return 0;
> >  }
> >
> > @@ -4959,6 +4966,7 @@ ixgbevf_dev_configure(struct rte_eth_dev *dev)
> >       struct rte_eth_conf *conf = &dev->data->dev_conf;
> >       struct ixgbe_adapter *adapter =
> >                       (struct ixgbe_adapter *)dev->data->dev_private;
> > +     uint16_t i;
> >
> >       PMD_INIT_LOG(DEBUG, "Configured Virtual Function port id: %d",
> >                    dev->data->port_id);
> > @@ -4981,11 +4989,17 @@ ixgbevf_dev_configure(struct rte_eth_dev *dev)
> >
> >       /*
> >        * Initialize to TRUE. If any of Rx queues doesn't meet the bulk
> > -      * allocation or vector Rx preconditions we will reset it.
> > +      * allocation or vector Rx preconditions we will reset it. We
> > +      * can only do this is there aren't any existing RX queues.
> >        */
> > +     for (i = 0; i < dev->data->nb_rx_queues; i++) {
> > +             if (dev->data->rx_queues[i])
> > +                     goto out;
> > +     }
> >       adapter->rx_bulk_alloc_allowed = true;
> >       adapter->rx_vec_allowed = true;
> >
> > +out:
> >       return 0;
> >  }
> >
> > --
> > 2.9.5