On Sun, Dec 6, 2015 at 10:44 AM, Alexander Duyck
<alexander.du...@gmail.com> wrote:
> On Sun, Dec 6, 2015 at 8:31 AM, Tom Herbert <t...@herbertland.com> wrote:
>>> The only spot I think you and I disagreed on was the approach. I
>>> don't know if the hard push back does anything but punish the users by
>>> delaying the time needed to find a reasonable solution. I really
>>> think if we are going to get the hardware vendors to change their
>>> behavior we have to create a market demand for it. Having a bit of
>>> marketable data showing the folly of this approach versus the 1's
>>> compliment checksum would probably do more to encourage and/or shame
>>> them into it than simply pushing for this based on engineering
>>> opinion.
>>>
>> I don't know what "marketable data" means. But I do know that we're
>> like 70 postings into this thread, into the third patch set regarding
>> this, yet nobody has bothered to contribute any data on what these
>> patches do and what the quantifiable benefits are with HW offload of
>> these protocols. I would test this stuff myself, but I don't have
>> access to any NICs with necessary support. If someone else can start
>> testing and providing meaningful data it would be most helpful...
>
> Here is an example of something kind of like what I am talking about:
> http://www.mellanox.com/related-docs/whitepapers/CB_Intel_XL710.pdf
>
> I have seen evidence of the gains first hand. The biggest gain ends
> up being the result of GRO, and you cannot make use of GRO without
> some form of Rx checksum offload.
>
Right, but we recoup the gains of GRO simply by enabling the UDP
checksum. This works for all the UDP encapsulations, and probably
about all NICs in deployment. You don't need protocol specific
offloads for this. I have posted performance data many times on this,
it is a clear win.
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