Re: [dpdk-dev] [PATCH] net/ixgbe: update data->eth_link status on start

[Chas Williams <3chas3@gmail.com>]

On Fri, Apr 6, 2018 at 10:52 AM, Zhang, Helin <helin.zhang@intel.com> wrote:
>
>
>> -----Original Message-----
>> From: Chas Williams [mailto:3chas3@gmail.com]
>> Sent: Monday, April 2, 2018 9:57 PM
>> To: Zhang, Qi Z
>> Cc: Zhang, Helin; dev@dpdk.org; Lu, Wenzhuo; Ananyev, Konstantin; Charles
>> (Chas) Williams
>> Subject: Re: [dpdk-dev] [PATCH] net/ixgbe: update data->eth_link status on
>> start
>>
>> On Mon, Apr 2, 2018 at 9:45 AM, Zhang, Qi Z <qi.z.zhang@intel.com> wrote:
>> >
>> >
>> >> -----Original Message-----
>> >> From: Chas Williams [mailto:3chas3@gmail.com]
>> >> Sent: Monday, April 2, 2018 9:38 PM
>> >> To: Zhang, Qi Z <qi.z.zhang@intel.com>
>> >> Cc: Zhang, Helin <helin.zhang@intel.com>; dev@dpdk.org; Lu, Wenzhuo
>> >> <wenzhuo.lu@intel.com>; Ananyev, Konstantin
>> >> <konstantin.ananyev@intel.com>; Charles (Chas) Williams
>> >> <chas3@att.com>
>> >> Subject: Re: [dpdk-dev] [PATCH] net/ixgbe: update data->eth_link
>> >> status on start
>> >>
>> >> On Mon, Apr 2, 2018 at 8:40 AM, Zhang, Qi Z <qi.z.zhang@intel.com> wrote:
>> >> > Hi Williams:
>> >> >
>> >> >> -----Original Message-----
>> >> >> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Chas Williams
>> >> >> Sent: Saturday, March 31, 2018 1:22 AM
>> >> >> To: Zhang, Helin <helin.zhang@intel.com>
>> >> >> Cc: dev@dpdk.org; Lu, Wenzhuo <wenzhuo.lu@intel.com>; Ananyev,
>> >> >> Konstantin <konstantin.ananyev@intel.com>; Charles (Chas) Williams
>> >> >> <chas3@att.com>
>> >> >> Subject: Re: [dpdk-dev] [PATCH] net/ixgbe: update data->eth_link
>> >> >> status on start
>> >> >>
>> >> >> On Fri, Mar 30, 2018 at 12:30 PM, Zhang, Helin
>> >> >> <helin.zhang@intel.com>
>> >> >> wrote:
>> >> >> >
>> >> >> >
>> >> >> >> -----Original Message-----
>> >> >> >> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Chas
>> >> >> >> Williams
>> >> >> >> Sent: Wednesday, February 14, 2018 6:56 AM
>> >> >> >> To: dev@dpdk.org
>> >> >> >> Cc: Lu, Wenzhuo; Ananyev, Konstantin; Charles (Chas) Williams
>> >> >> >> Subject: [dpdk-dev] [PATCH] net/ixgbe: update data->eth_link
>> >> >> >> status on start
>> >> >> >>
>> >> >> >> From: "Charles (Chas) Williams" <chas3@att.com>
>> >> >> >>
>> >> >> >> dev->data->eth_link isn't updated until the first interrupt.
>> >> >> >> dev->data->If a
>> >> >> >> link is carrier down, then this interrupt may never happen.
>> >> >> >> Before we finished starting the PMD, call
>> >> >> >> ixgbe_dev_link_update() to ensure we
>> >> >> have a valid status.
>> >> >> >>
>> >> >> >> Signed-off-by: Chas Williams <chas3@att.com>
>> >> >> >> ---
>> >> >> >>  drivers/net/ixgbe/ixgbe_ethdev.c | 4 ++++
>> >> >> >>  1 file changed, 4 insertions(+)
>> >> >> >>
>> >> >> >> diff --git a/drivers/net/ixgbe/ixgbe_ethdev.c
>> >> >> >> b/drivers/net/ixgbe/ixgbe_ethdev.c
>> >> >> >> index 37eb668..27d29dc 100644
>> >> >> >> --- a/drivers/net/ixgbe/ixgbe_ethdev.c
>> >> >> >> +++ b/drivers/net/ixgbe/ixgbe_ethdev.c
>> >> >> >> @@ -2666,6 +2666,8 @@ ixgbe_dev_start(struct rte_eth_dev *dev)
>> >> >> >>       if (err)
>> >> >> >>               goto error;
>> >> >> >>
>> >> >> >> +     ixgbe_dev_link_update(dev, 0);
>> >> >> > It is called in rte_eth_dev_start() if lsc is not enabled, and
>> >> >> > it is not needed here to avoid any duplication.
>> >> >> > BTW, did you see any issue or just check the code? Thanks!
>> >> >>
>> >> >> Yes, I see an issue with bonding.  If LSC is enabled, then
>> >> >> link_status isn't set until the first interrupt to update the link
>> >> >> status.  If a link is down, this interrupt may never happen result
>> >> >> in
>> >> link_status being somewhat undefined.
>> >> >
>> >> > Is your issue only happened on VF?
>> >> > For PF, I saw ixgbe_check_link is called at ixgbe_dev_start, so
>> >> > link status is
>> >> assume be updated.
>> >> > If you think it is just missed in VF, can you implemented this in
>> >> > the similar way
>> >> as PF?
>> >>
>> >> No, I don't believe it's isolated to VF.  ixgbe_check_link() doesn't
>> >> update (atomically write) the dev->data->dev_link.  After
>> >> .dev_start() finishes, I need the link_status of the adapter to be set.
>> >
>> > I saw dev_link.link_status does be updated.
>> >         err = ixgbe_check_link(hw, &speed, &link_up, 0);
>> >         if (err)
>> >                 goto error;
>> >         dev->data->dev_link.link_status = link_up;
>>
>> That doesn't fill in link_duplex, link_speed, or link_autoneg.
>> 802.3ad requires that all the ports of
>> the same bonding group have the same speed and duplex.  I need to be able to
>> check the speed and the duplex at least (and autoneg as well).
> I am thinking it might be a bit late to update the link status in dev_start(), and we
> need to check if the full link update should be done in eth_ixgbe_dev_init() and
> eth_ixgbevf_dev_init().
> @Qi, Chas, could you help to check if my idea is correct?
> Also I think this applies to other PMDs, e.g. igb, i40e. At least we need to double check.

I don't think link_status needs updated sooner unless you think there
is some path
in the PMDs that need to check the link status.  I am not aware of anything like
that in the Intel PMDs (but certainly not an expert in their
behavior).  Since the DPDK
API is inherently single-threaded there's no external reason to have
the link status
updated until just before .dev_start() finishes.

>
> Regards,
> Helin
>
>>
>> >
>> >> I can't wait until I hope the first
>> >> interrupt has happened that would update
>> >> dev->data->dev_link.  How long would I wait?  I don't really care if
>> >> the link is down,
>> >> or up, or whatever, but it can't be partially filled in.  Bonding (in
>> >> 802.3ad) wants the
>> >> links to be similarly configured.
>> >>
>> >> >
>> >> > Regards
>> >> > Qi
>> >> >
>> >> >>
>> >> >> >
>> >> >> > /Helin
>> >> >> >
>> >> >> >> +
>> >> >> >>  skip_link_setup:
>> >> >> >>
>> >> >> >>       if (rte_intr_allow_others(intr_handle)) { @@ -5033,6
>> >> >> >> +5035,8 @@ ixgbevf_dev_start(struct rte_eth_dev *dev)
>> >> >> >>
>> >> >> >>       ixgbevf_dev_rxtx_start(dev);
>> >> >> >>
>> >> >> >> +     ixgbevf_dev_link_update(dev, 0);
>> >> >> >> +
>> >> >> >>       /* check and configure queue intr-vector mapping */
>> >> >> >>       if (rte_intr_cap_multiple(intr_handle) &&
>> >> >> >>           dev->data->dev_conf.intr_conf.rxq) {
>> >> >> >> --
>> >> >> >> 2.9.5
>> >> >> >