Netmap support for Virtual network driver

[Luigi Rizzo]

On Fri, Dec 13, 2013 at 4:48 PM, Thirunavukarasu Sengalvarayan -X (tsengalv
- HCL TECHNOLOGIES LIMITED at Cisco) <tsengalv at cisco.com> wrote:

>   (Continuing with below mail thread.)
>
>
>
> Hi Luigi,
>
>
>
> Thanks a lot for your quick response.
>
> Yes we have the source base for hyper-v network driver.
>
> Could you please provide us the patch for Netmap support in Hyper-v
> Network drivers.
>

sorry i meant that if you send us the guest driver sources
we can try to add netmap support to them.
 

>  Hyper-v has two kinds of NIC, emulated and Synthetic.
>
> In general emulated network drivers are relatively slow when compared to
> Synthetic network drivers.
>
 Hence we planned to use synthetic network drivers(netvsc).
>
> You have pointed that we could use e1000 emulation as another option.
>
> Which driver would be better in terms of performance, Netmap with
> emulation driver or Netmap with synthetic driver?
>
>
>

it all depends on your usage pattern, on how bad is the
hypervisor at emulating the e1000, and especially
how slow is the network backend (virtual switch) used.

In general netmap operates in batches and especially for the
receive side it overcomes some of the limitation of emulation,
often leaving the virtual switch as the bottlenecks.

In the paper we referenced we elaborate further.

in practice, i'd suggest to start with e1000 emulation and
see what kind of performance you are getting, and post the
numbers so i can tell whether it is worthwhile trying
to use a modified synthetic driver.

cheers
luigi


>  Thanks
>
> Thiru.
>
>
>
> ---------- Forwarded message ----------
> From: *Luigi Rizzo* <rizzo at iet.unipi.it>
> Date: Fri, Dec 13, 2013 at 12:54 AM
> Subject: Re: Netmap support for Virtual network driver
> To: Thirunavukarasu S <gs.thiru1983 at gmail.com>
> Cc: "freebsd-net at freebsd.org" <net at freebsd.org>
>
>
>
>
>
> On Thu, Dec 12, 2013 at 7:02 PM, Thirunavukarasu S <gs.thiru1983 at gmail.com>
> wrote:
>
> Hi
>
> I am running a Virtual Linux machine on Hyper-v Microsoft Hypervisor.
>
> I am using netvsc drivers provided by Microsoft for virtual interfaces.
>
> Now I would like to add Netmap support for netvsc driver, after coming to
> know about its wide advantages.
>
> Does Netmap support for Microsoft Hyper-v Network drivers is already in
> place.
>
> or could you help in integrating netmap support in our netvsc drivers.
>
>
>
> we can definitely help with the integration
>
> as long as you have the hyperv
>
> drivers for the guest in source format
>
>
>
> another option might be to use the e1000 emulation
>
> in hyperv.
>
>
>
> but in any case don't hold your breath for performance,
>
> because chances are that the network I/O path in the
>
> hypervisor (hyperv in this case) is not able to
>
> sustain the data rates that netmap can generate.
>
>
>
> See the paper at this link to see what we did for QEMU/KVM
>
>
>
> http://info.iet.unipi.it/~luigi/papers/20130903-rizzo-ancs.pdf
>
>
>
>
>
> to make it run at netmap speeds
>
>
>
> cheers
>
> luigi
>
>
>
> Thanks
> Thiru.
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>
>
>
>
> --
> -----------------------------------------+-------------------------------
>  Prof. Luigi RIZZO, rizzo at iet.unipi.it  . Dip. di Ing. dell'Informazione
>  http://www.iet.unipi.it/~luigi/        . Universita` di Pisa
>  TEL      +39-050-2211611               . via Diotisalvi 2
>  Mobile   +39-338-6809875               . 56122 PISA (Italy)
> -----------------------------------------+-------------------------------
>
>
>



-- 
-----------------------------------------+-------------------------------
 Prof. Luigi RIZZO, rizzo at iet.unipi.it  . Dip. di Ing. dell'Informazione
 http://www.iet.unipi.it/~luigi/        . Universita` di Pisa
 TEL      +39-050-2211611               . via Diotisalvi 2
 Mobile   +39-338-6809875               . 56122 PISA (Italy)
-----------------------------------------+-------------------------------