Re: Add PGM protocol support to the IP stack

Andi Kleen
2010-03-22T16:36:09Z

On Mon, Mar 22, 2010 at 09:20:42AM -0500, Christoph Lameter wrote:
> On Fri, 19 Mar 2010, Andi Kleen wrote:
>
> > Christoph Lameter <cl@linux-foundation.org> writes:
> > >
> > > I know about the openpgm implementation. Openpbm does this at the user
> > > level and requires linking to a library. It is essentially a communication
> > > protocol done in user space. It has privilege issues because it has to
> > > create PGM packets via a raw socket.
> >
> > That seems like a poor reason alone to put something into the kernel
> > Perhaps you rather need some way to have unpriviledged raw sockets?
>
> Not the only reason. There are also performance implications. NAKing and
> other control messages from user space are a pain and the available
> implementations add numerous threads just to control the timing of control
> messages and the expiration of data etc. Its difficult to listen to a PGM
> port from user space. You have to get all messages for the PGM protocol
> and then filter in each process.

Ok that sounds like a good reason to have a kernel protocol.
Thanks.

Multicast reliable kernel protocols are somewhat new, I guess one
would need to make sure to come up with a clean generic interface
for them first.

-Andi

--
ak@linux.intel.com -- Speaking for myself only.