On Fri, 2007-20-07 at 08:18 +0100, Stephen Hemminger wrote: > You may see worse performance with batching in the real world when > running over WAN's. Like TSO, batching will generate back to back packet > trains that are subject to multi-packet synchronized loss.
Has someone done any study on TSO effect? Doesnt ECN with a RED router help on something like this? I find it suprising that a single flow doing TSO would overwhelm a routers buffer. I actually think the value of batching as far as TCP is concerned is propotional to the number of flows. i.e the more flows you have the more batching you will end up doing. And if TCPs fairness is the legend talk it has been made to be, then i dont see this as problematic. BTW, something i noticed regards to GSO when testing batching: For TCP packets slightly above MDU (upto 2K), GSO gives worse performance than non-GSO. Actually has nothing to do with batching, rather it works the same way with or without batching changes. Another oddity: Looking at the flow rate from a purely packets/second (I know thats a router centric view, but i found it strange nevertheless) - you see that as packet size goes up, the pps also goes up. I tried mucking around with nagle etc, but saw no observable changes. Any insight? My expectation was that the pps would stay at least the same or get better with smaller packets (assuming theres less data to push around). cheers, jamal - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
