[e2e] Are Packet Trains / Packet Bursts a Problem in TCP?

Rick Jones perfgeek at mac.com
Wed Sep 27 17:02:38 PDT 2006

>The question whether or not we can implement fine-grained pacing in software 
>might be becoming less relevant now that the silicon industry is irreversibly 
>pushing with TCP segmentation offload implementations in hardware. 

We industry types have to because the researchers keep adding straws to TCP's back and increasing the path length :) And because the IEEE types won't standardize a larger MTU each time they increase the bit-rate by an order of magnitude...

>that the OS typically feeds a TSO engine with at least a 32 or 64 kbyte raw 
>data chunk per single TCP session, this corresponds to a 22 or 44 segment 
>wire-speed burst at minimum.  Thinking what things might look like if 
>multiple such streams would get synchronized is quite scarry...

If they trigger losses, then the cwnd's kick-in and the TSO's become smaller.

rick jones

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