Subject: Re: [RFC] netem: de-GSO packets before enqueing

From: Hagen Paul Pfeifer <[email-masked]>
Date: Sat, 14 Jan 2012 17:06:46 +0100

* Stephen Hemminger | 2012-01-12 16:57:20 [-0800]:

>Probably something like this is needed (untested).
>
>This issue was discovered when looking at the skb_checksum path for the
>netem corruption operation, but it is a general problem.
>Network emulation operations like corruption and drop want to operate
>on a per-packet (not per-segment) basis. This patch does GSO in software
>if necessary to break up packets.  Code is similar to logic in xfrm_output.
>
>Although it appears that the operation is not work conserving, it is okay
>because the higher level qdisc operations account for packets by incrementing
>by gso_size.

Thanks Stephen! Corruption is currently unusable if GSO is enabled. We disable
GSO/TSO on all our test machines therefore.

I have a larger set of patches for the corruption option for this merge
window. We will now test your patch (and the hopefully following qdisc len
updated patch).

Hagen