netdev - Re: [PATCH net-next 0/8] nfp: offload LAG for tc flower egress

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Message-ID: <20180529220947.GC2367@nanopsycho>
Date:   Wed, 30 May 2018 00:09:47 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     John Hurley <john.hurley@...ronome.com>
Cc:     Jakub Kicinski <jakub.kicinski@...ronome.com>,
        David Miller <davem@...emloft.net>,
        Linux Netdev List <netdev@...r.kernel.org>,
        oss-drivers@...ronome.com, Jay Vosburgh <j.vosburgh@...il.com>,
        Veaceslav Falico <vfalico@...il.com>,
        Andy Gospodarek <andy@...yhouse.net>
Subject: Re: [PATCH net-next 0/8] nfp: offload LAG for tc flower egress

Tue, May 29, 2018 at 04:08:48PM CEST, john.hurley@...ronome.com wrote:
>On Sat, May 26, 2018 at 3:47 AM, Jakub Kicinski
><jakub.kicinski@...ronome.com> wrote:
>> On Fri, 25 May 2018 08:48:09 +0200, Jiri Pirko wrote:
>>> Thu, May 24, 2018 at 04:22:47AM CEST, jakub.kicinski@...ronome.com wrote:
>>> >Hi!
>>> >
>>> >This series from John adds bond offload to the nfp driver.  Patch 5
>>> >exposes the hash type for NETDEV_LAG_TX_TYPE_HASH to make sure nfp
>>> >hashing matches that of the software LAG.  This may be unnecessarily
>>> >conservative, let's see what LAG maintainers think :)
>>>
>>> So you need to restrict offload to only certain hash algo? In mlxsw, we
>>> just ignore the lag setting and do some hw default hashing. Would not be
>>> enough? Note that there's a good reason for it, as you see, in team, the
>>> hashing is done in a BPF function and could be totally arbitrary.
>>> Your patchset effectively disables team offload for nfp.
>>
>> My understanding is that the project requirements only called for L3/L4
>> hash algorithm offload, hence the temptation to err on the side of
>> caution and not offload all the bond configurations.  John can provide
>> more details.  Not being able to offload team is unfortunate indeed.
>
>Hi Jiri,
>Yes, as Jakub mentions, we restrict ourselves to L3/L4 hash algorithm
>as this is currently what is supported in fw.

In mlxsw, a default l3/l4 is used always, no matter what the
bonding/team sets. It is not correct, but it works with team as well.
Perhaps we can have NETDEV_LAG_HASH_UNKNOWN to indicate to the driver to
do some default? That would make the "team" offload functional.

>Hopefully this will change as fw features are expanded.
>I understand the issue this presents with offloading team.
>Perhaps resorting to a default hw hash for team is acceptable.
>John