Re: [coLinux-devel] Kernel-to-Kernel networking support?

[Christian K. <cka...@mi...>]

Dan Aloni <da...@co...>:
>The cause of the latency is scheduling, not copying.

This may be a better explanation. :-) Well, at least I don't really
mind: by bouncing the network data forth and back between the Windows
kernel and the userspace, we both get a scheduling problem and some copy
operations.=20

So there are two options:=20

- Getting the scheduling problem solved.

- Not passing the network data into userspace, but sending it directly
  to the network.=20

I think that the first solution will not really satisfy our high
performance requirements.=20

>I agree, this might solve the scheduling problem. However, I'm not an=20
>expert in Windows kernel programming so connecting the TAP driver with
>the coLinux driver is not something I've managed to figure out how to
>do so far, nor I dedicated enough time for it.

I've been thinking about a way to extend the LINUX.SYS Windows kernel
driver with a linked-in module that attaches itself to a configurable
network device via NDIS API calls. This way we get a opportunity to
directly insert Ethernet frames into the network device and to register
a callback as well, which is going to be invoked every time when a
packet on the specified interface arrives.=20

This would have the advantage of the lowest possible overhead. There are
two disadvantages as well: it is somewhat hard to write & debug and we
need a separate IP address for the coLinux VM.=20

Any comments? Suggestions?

Regards
  Christian

--=20
Dipl.-Inf. Christian Kauhaus                               <><
Lehrstuhl Rechnerarchitektur und -kommunikation=20
Institut fuer Informatik =B7 Ernst-Abbe-Platz 1-2 =B7 D-07743 Jena
Tel.: (+49) 3641 9 46376 =B7 Fax: (+49) 3641 9 46372 =B7 Raum 3217