[ofa-general] Re: [PATCH 00/10] Implement batching skb API

Stephen Hemminger [off-list ref] wrote on 07/20/2007
12:48:48 PM:

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. The problem is

that

intermediate router queues are often close to full, and when a long

string

of packets arrives back to back only the first ones will get in, the rest
get dropped.  Normal sends have at least minimal pacing so they are less
likely do get synchronized drop.

Also forgot to mention in the previous mail, if performance is seen to be
dipping,
batching can be disabled on WAN's by:

echo 0 > /sys/class/net/<dev>/tx_batch_skbs

and use batching on local/site networks in that case.