Re: [PATCH] net/i40e: enable max frame size at port level

[David Marchand <david.marchand@redhat.com>]

On Mon, Dec 12, 2022 at 2:53 PM David Marchand
<david.marchand@redhat.com> wrote:
> On Tue, Dec 7, 2021 at 10:02 AM <dapengx.yu@intel.com> wrote:
> >
> > From: Dapeng Yu <dapengx.yu@intel.com>

I got a bounce on his mail address, so adding people who
submitted/reviewed later fixes for this change.

Please guys, have a look.


> >
> > Currently max frame size is set at queue level, which makes the values
> > of the following counters wrong when a jumbo frame is received.
> >
> > The expected value:
> > rx_good_bytes: 0
> > rx_errors: 1
> > rx_oversize_errors: 1
> >
> > The actual value:
> > rx_good_bytes: 1626
> > rx_errors: 0
> > rx_oversize_errors: 0
> >
> > This patch enables setting max frame size at port level, and makes the
> > values above right.
> >
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Dapeng Yu <dapengx.yu@intel.com>
>
> I am looking again at this patch that triggered regressions in stable
> branches, when used with OVS.
>
>
> > ---
> >  drivers/net/i40e/i40e_ethdev.c | 41 ++++++++++++++++++++++++++++------
> >  1 file changed, 34 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/net/i40e/i40e_ethdev.c b/drivers/net/i40e/i40e_ethdev.c
> > index c0bfff43ee..ef9b2b2414 100644
> > --- a/drivers/net/i40e/i40e_ethdev.c
> > +++ b/drivers/net/i40e/i40e_ethdev.c
> > @@ -386,6 +386,7 @@ static int i40e_set_default_mac_addr(struct rte_eth_dev *dev,
> >                                       struct rte_ether_addr *mac_addr);
> >
> >  static int i40e_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu);
> > +static void i40e_set_mac_max_frame(struct rte_eth_dev *dev, uint16_t size);
> >
> >  static int i40e_ethertype_filter_convert(
> >         const struct rte_eth_ethertype_filter *input,
> > @@ -1709,11 +1710,6 @@ eth_i40e_dev_init(struct rte_eth_dev *dev, void *init_params __rte_unused)
> >          */
> >         i40e_add_tx_flow_control_drop_filter(pf);
> >
> > -       /* Set the max frame size to 0x2600 by default,
> > -        * in case other drivers changed the default value.
> > -        */
> > -       i40e_aq_set_mac_config(hw, I40E_FRAME_SIZE_MAX, TRUE, false, 0, NULL);
> > -
>
> If I understand correctly, the max framesize (9728) was always applied
> in dev_init, before this change.
>
>
> >         /* initialize RSS rule list */
> >         TAILQ_INIT(&pf->rss_config_list);
> >
> > @@ -2364,6 +2360,7 @@ i40e_dev_start(struct rte_eth_dev *dev)
> >         uint32_t intr_vector = 0;
> >         struct i40e_vsi *vsi;
> >         uint16_t nb_rxq, nb_txq;
> > +       uint16_t max_frame_size;
> >
> >         hw->adapter_stopped = 0;
> >
> > @@ -2502,6 +2499,9 @@ i40e_dev_start(struct rte_eth_dev *dev)
> >                             "please call hierarchy_commit() "
> >                             "before starting the port");
> >
> > +       max_frame_size = dev->data->mtu + I40E_ETH_OVERHEAD;
> > +       i40e_set_mac_max_frame(dev, max_frame_size);
> > +
>
> And now this change tries to configure, at dev_start step, the max
> frame size that the application actually requested.
> Which seems ok, afaiu.
>
>
> >         return I40E_SUCCESS;
> >
> >  tx_err:
> > @@ -2848,6 +2848,9 @@ i40e_dev_set_link_down(struct rte_eth_dev *dev)
> >         return i40e_phy_conf_link(hw, abilities, speed, false);
> >  }
> >
> > +#define CHECK_INTERVAL             100  /* 100ms */
> > +#define MAX_REPEAT_TIME            10  /* 1s (10 * 100ms) in total */
> > +
> >  static __rte_always_inline void
> >  update_link_reg(struct i40e_hw *hw, struct rte_eth_link *link)
> >  {
> > @@ -2914,8 +2917,6 @@ static __rte_always_inline void
> >  update_link_aq(struct i40e_hw *hw, struct rte_eth_link *link,
> >         bool enable_lse, int wait_to_complete)
> >  {
> > -#define CHECK_INTERVAL             100  /* 100ms */
> > -#define MAX_REPEAT_TIME            10  /* 1s (10 * 100ms) in total */
> >         uint32_t rep_cnt = MAX_REPEAT_TIME;
> >         struct i40e_link_status link_status;
> >         int status;
> > @@ -6719,6 +6720,7 @@ i40e_dev_handle_aq_msg(struct rte_eth_dev *dev)
> >                         if (!ret)
> >                                 rte_eth_dev_callback_process(dev,
> >                                         RTE_ETH_EVENT_INTR_LSC, NULL);
> > +
> >                         break;
> >                 default:
> >                         PMD_DRV_LOG(DEBUG, "Request %u is not supported yet",
> > @@ -12103,6 +12105,31 @@ i40e_cloud_filter_qinq_create(struct i40e_pf *pf)
> >         return ret;
> >  }
> >
> > +static void
> > +i40e_set_mac_max_frame(struct rte_eth_dev *dev, uint16_t size)
> > +{
> > +       struct i40e_hw *hw = I40E_DEV_PRIVATE_TO_HW(dev->data->dev_private);
> > +       uint32_t rep_cnt = MAX_REPEAT_TIME;
> > +       struct rte_eth_link link;
> > +       enum i40e_status_code status;
> > +
> > +       do {
> > +               update_link_reg(hw, &link);
> > +               if (link.link_status)
> > +                       break;
> > +
> > +               rte_delay_ms(CHECK_INTERVAL);
> > +       } while (--rep_cnt);
> > +
> > +       if (link.link_status) {
> > +               status = i40e_aq_set_mac_config(hw, size, TRUE, 0, false, NULL);
> > +               if (status != I40E_SUCCESS)
> > +                       PMD_DRV_LOG(ERR, "Failed to set max frame size at port level");
> > +       } else {
> > +               PMD_DRV_LOG(ERR, "Set max frame size at port level not applicable on link down");
> > +       }
>
> But here, applying the configuration when the link is up only, looks
> very wrong to me.
>
> If the link is down, then this configuration will never get applied.
> And what is worse, the application has no indication of it since no
> error code is propagated.
>
> So the application thinks the port started, but it will never get "big" packets.
>
>
> Like for example:
> - unplug cable,
> - start testpmd and configure mtu to 9000,
> # dpdk-testpmd -l 0,2,3 --in-memory -a 0000:05:00.1 -- -i --disable-link-check
> ...
> Configuring Port 0 (socket 0)
> i40e_set_mac_max_frame(): Set max frame size at port level not
> applicable on link down
> Port 0: 3C:FD:FE:A0:A4:C5
> Done
>
> testpmd> port stop 0
> Stopping ports...
> Done
>
> testpmd> port config mtu 0 9000
>
> testpmd> port start 0
> i40e_set_mac_max_frame(): Set max frame size at port level not
> applicable on link down
> Port 0: 3C:FD:FE:A0:A4:C5
> Done
>
> - plug back cable, and send "big" packets, like for example ping with
> -s 8000 from other side of the cable,
> - no "big" packet is received on the dpdk port, and its rx_errors
> xstats keeps increasing,
>
>
> Looking at the original change, why did you not ignore link status state?
> I would just move "i40e_aq_set_mac_config(hw, I40E_FRAME_SIZE_MAX,
> TRUE, false, 0, NULL);" in dev_start.
>
>


-- 
David Marchand