netdev - Re: [PATCH net-next v4 4/5] bnx2x: Use NETIF_F_GRO

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Date:   Wed, 13 Dec 2017 12:45:46 -0800
From:   Michael Chan <michael.chan@...adcom.com>
To:     "Chopra, Manish" <Manish.Chopra@...ium.com>
Cc:     "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "andrew.gospodarek@...adcom.com" <andrew.gospodarek@...adcom.com>,
        "Elior, Ariel" <Ariel.Elior@...ium.com>,
        Dept-Eng Everest Linux L2 <Dept-EngEverestLinuxL2@...ium.com>
Subject: Re: [PATCH net-next v4 4/5] bnx2x: Use NETIF_F_GRO_HW.

On Wed, Dec 13, 2017 at 1:08 AM, Chopra, Manish
<Manish.Chopra@...ium.com> wrote:
>
> Hi Michael,  There seems a behavioral change here. This driver support two HW aggregation modes [LRO and GRO]
> With the changes, Interfaces come with HW GRO enabled and LRO disabled by default as opposed to earlier where interfaces used to come with LRO enabled.

Right.  Before, you had both NETIF_F_GRO and NETIF_F_LRO set and the
code looked at NETIF_F_LRO first and turned on LRO.

Now, we set NETIF_F_GRO and NETIF_F_GRO_HW by default.  NETIF_F_LRO is
turned off since NETIF_F_GRO_HW is on.

If you want, I can change it back to the old default.

>
> Also, there seems some problem when turning on LRO even after GRO disable.
> When I tried to disable GRO and then tried to enable LRO it didn't go well. Not sure why ?

I just put an old BCM57810 card into my machine and it works for me.
As long as I turn off GRO or GRO_HW, I can turn on LRO.

[root@...alhost bnx2x]# ethtool -K p1p1 lro on
Cannot get device udp-fragmentation-offload settings: Operation not supported
Cannot get device udp-fragmentation-offload settings: Operation not supported
Could not change any device features
[root@...alhost bnx2x]# ethtool -K p1p1 gro off
Cannot get device udp-fragmentation-offload settings: Operation not supported
Cannot get device udp-fragmentation-offload settings: Operation not supported
Actual changes:
generic-receive-offload: off
large-receive-offload: on
rx-gro-hw: off [requested on]
[root@...alhost bnx2x]# ethtool -K p1p1 lro on
Cannot get device udp-fragmentation-offload settings: Operation not supported
Cannot get device udp-fragmentation-offload settings: Operation not supported