User-level network stack

[Howard Chu <hyc@symas.com>]

Quite a while back I talked about optimizing select/epoll/whatever using 
mmap'd memory shared between user space and the kernel for the event table.

http://www.openldap.org/lists/openldap-devel/200411/msg00088.html

These guys have gone even further, and use mapped memory to bring the entire 
network stack up to user level:

http://www.openonload.org/openonload-google-talk.pdf

Their paper talks about the work they did with two particular 10Gbit NICs. I 
find this interesting because in these benchmarks I ran

http://connexitor.com/blog/pivot/entry.php?id=191

the NIC interrupt overhead was 100% of a CPU core, and that was only on 1Gbit 
ethernet. Clearly for heavy-load deployments a better network solution is 
needed. It sounds like maybe the OpenOnload guys have a better approach.
--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/