Re: [Xen-devel] [PATCH v7 0/2] public/io/netif.h: support for toeplitz hashing

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Bob Liu [mailto:bob.liu@xxxxxxxxxx]
> Sent: 02 February 2016 05:02
> To: Paul Durrant
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] [PATCH v7 0/2] public/io/netif.h: support for
> toeplitz hashing
> 
> Hi Paul,
> 
> On 01/12/2016 05:58 PM, Paul Durrant wrote:
> > This series documents changes needed to support toeplitz hashing in a
> > backend, configurable by the frontend.
> >
> > Patch #1 adds further clarifications to the receive and transmit wire
> > formats.
> >
> > Patch #2 documents a new 'control ring' for passing bulk data between
> > frontend and backend. This is needed for passing the hash mapping table
> > and hash key. It also documents messages to allow a frontend to configure
> > toeplitz hashing and a new extra info segment that can be used for passing
> > hash values along with packets on both the transmit and receive side.
> >
> 
> I have a question, why not make the "netif_ctrl_request" a part of the extra
> info segment?
> So that can reuse the origin transmit shared ring.

That was an option but I think it's pretty hacky. Also, extra info segments are 
pretty small. The multicast control protocol uses that mechanism and it's quite 
inelegant. I also think a dedicated ring for out-of-band control messages is 
likely to be of further use in the future.

  Paul

 
> 
> --
> Regards,
> -Bob

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