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Date:      Wed, 20 May 2015 17:18:36 +0200
From:      Luigi Rizzo <rizzo@iet.unipi.it>
To:        Hans Petter Selasky <hps@selasky.org>
Cc:        Blake Caldwell <caldweba@colorado.edu>,  "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>, Oded Shanoon <odeds@mellanox.com>
Subject:   Re: netmap and mlx4 driver status (linux)
Message-ID:  <CA%2BhQ2%2BjM9bvSQ8rjB=8ikZ-DtuVqYzj84MAGRTd75UJX0_Ur0g@mail.gmail.com>
In-Reply-To: <555C9F30.8070405@selasky.org>
References:  <3010CFE2-66B7-416B-92DE-C1B669CC33BE@colorado.edu> <555C9F30.8070405@selasky.org>

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hi all,

the mlx4 netmap patch (for linux only) was something i did long
ago when i had some mellanox hardware available, but no documentation
so i had to resort to interpreting what the linux driver did.

At the time i had the following performance (on PCIe v2 bus):

10G ports: tx/rx at about  7 Mpps with 64 byte packets
     could saturate the link with 192 or 256 byte packets

40G ports: tx/rx at about 11 Mpps with 64 byte packets
     max 28 Gbit/s even with 1500 byte frames

I don't know if the limited performance was due to bus,
firmware or lack of documentation, anyways this is not
something i can or want to deal with.

My understanding is that Mellanox does not release programming
documentation, so the only way to have native netmap support
for that card would be to have Mellanox work on that and
provide a suitable patch.

I do not expect more than a week's work (the typical extra
code in each driver is about 500 lines, and very simple)
for someone with access to documentation. Also, the patch
for FreeBSD and Linux is typically very similar so once we
have a driver for one, the other would be trivial.

It would be of course great to add Mellanox to the list of
devices with native netmap support, together with Chelsio
and Intel.

Perhaps Hans (who may have contacts) can talk to the right
people and figure out. On my side, I am happy to give directions
on what needs to be done and import any patch that should
be made available.

cheers
luigi

On Wed, May 20, 2015 at 4:50 PM, Hans Petter Selasky <hps@selasky.org>
wrote:

> On 05/20/15 16:13, Blake Caldwell wrote:
>
>> Hello,
>>
>> I noticed that the mlx4_en patch for netmap is LINUX/wip-patches, so they
>> are not enabled in the normal build process. I'm curious about the status
>> of mlx4 support?
>>
>> If additional work to the patches is needed, any details as to what the
>> issues were.
>>
>> Any info would be great! Thanks in advance!
>>
>>
> Hi Blake,
>
> The MLX4 driver is being actively maintained in -stable and -current.
> Regarding netmap support for the FreeBSD MLX4 en driver, I'm not sure.
> Maybe Oded knows, CC'ed? Do you have a link for the patch you are referring?
>
> This there any particular use-case you are interested in?
>
> --HPS
>
>
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>



-- 
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 Prof. Luigi RIZZO, rizzo@iet.unipi.it  . Dip. di Ing. dell'Informazione
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 TEL      +39-050-2217533               . via Diotisalvi 2
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