On Mon, Mar 22, 2010 at 09:20:42AM -0500, Christoph Lameter wrote:

On Fri, 19 Mar 2010, Andi Kleen wrote:

quoted

Christoph Lameter [off-list ref] writes:

quoted

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.