patch for test (Was: tcp_output starving -- is due to mbuf get delay?)

Borje Josefsson bj at
Fri Apr 18 09:58:12 PDT 2003

On Thu, 17 Apr 2003 22:12:02 PDT "Jin Guojun [NCS]" wrote:

> I have modified the sockbuf and mbuf operation to double the throughput over
> high bandwidth delay product path.
> The patch is available at:
> The current modification is for tcp transmission only.
> I have adapted some code of uipc_socket2.c from Sam Leffler
> for tcp receiver, but it has not been tested yet, so the tcp_input.p is empty.
> I ignored all record chain (m_nextpkt) related code. The details is explained at
> Once the tcp_input code is tested, I will submit the patch to bugs at
> I may submit the patch regardless if tcp_input code works or not, because the
> tcp
> sender (server) is more important in high-speed network than the receiver
> (client).
> It is appreciated if any one can verify the patch and provide feedback.

OK. I have now tried this patch on a newly-installed 4.8R. The patch 
applied fine. When the sysctl net.inet.tcp.liondmask is unset, everything 
seems OK, but when setting it to 7 (as specified with the patch 
instructions) i get:

  Fatal trap 12: page fault while in kernel mode.
  (I could write down all the stuff on addresses etc if it makes sense)

when I run ttcp to test the performance.

This is repeatable.

I'm willing to test more, if someone provides me with some hints on what 
to do.


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