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From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: Having troubles binding an SR-IOV VF to
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Date: Thu, 1 Oct 2015 07:54:11 -0700
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Cc: "dev@dpdk.org" <dev@dpdk.org>, Avi Kivity <avi@scylladb.com>,
 "Michael S. Tsirkin" <mst@redhat.com>
To: Vincent JARDIN <vincent.jardin@6wind.com>
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On Thu, 01 Oct 2015 11:42:23 +0200
Vincent JARDIN <vincent.jardin@6wind.com> wrote:

> On 01/10/2015 11:22, Avi Kivity wrote:
> >> As far as I could see, without this kind of motivation, people do not
> >> even want to try.
> >
> > You are mistaken.  The problem is a lot harder than you think.
> >
> > People didn't go and write userspace drivers because they were lazy.
> > They wrote them because there was no other way.
> 
> I disagree, it is possible to write a 'partial' userspace driver.
> 
> Here it is an example:
>    http://dpdk.org/browse/dpdk/tree/drivers/net/mlx4
> 
> It benefits of the kernel's capabilities while the userland manages only 
> the IOs.
> 
> There were some tentative to get it for other (older) drivers, named 
> 'bifurcated drivers', but it is stalled.
> 

And in our testing the mlx4 driver performance is terrible.
That maybe because of the overhead of infiniband library.