tcp_output starving -- is due to mbuf get delay?

Eric Anderson anderson at
Thu Apr 10 05:31:36 PDT 2003

David Gilbert wrote:
>>>>>>"Jin" == Jin Guojun <[DSD]" <j_guojun at>> writes:
> Jin> Some details was left behind -- The machine is 2 GHz Intel P4
> Jin> with 1 GB memory, so the delay is not from either CPU or lack of
> Jin> memory.
> I just want to quickly jump in with the comment that our GigE tests of
> routing through FreeBSD have exposed several-order-of-magnitude
> differences by changing ram/motherboard/which-slot-the-card-is-in.
> Do not assume that a fast CPU is the key.  We went through 10
> motherboards to commission the current routers ... and sometimes
> faster cpus would route slower (in various combinations of
> motherboards and RAM).

Wow - this is very interesting.  I have two machines with GigE in them, 
one has 6 gige nics (intel pro/1000T server), in a dual Xeon 1.5Ghz 
(P4), with 2gb of ram.  I haven't put it into production yet, so if 
there are any tests I can do, let me know.  It would be good to know the 
pitfalls before I bring it up live.. :)


Eric Anderson	   Systems Administrator      Centaur Technology
Attitudes are contagious, is yours worth catching?

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