netdev - Re: HTB, HFSC, PIE, FIFO stuck on 2.4Gbit on default values

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Date:	Tue, 03 Nov 2015 21:02:59 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Denys Fedoryshchenko <nuclearcat@...learcat.com>
Cc:	Netdev <netdev@...r.kernel.org>
Subject: Re: HTB, HFSC, PIE, FIFO stuck on 2.4Gbit on default values

On Wed, 2015-11-04 at 06:49 +0200, Denys Fedoryshchenko wrote:
> Tested now, can be reproduced on 4.3 as well.
> What is interesting, if i enable tso alone, and leave gso/gro off - it 
> is working fine. gso+gro on, tso off - fine also.
> But if i enable them all together - i trigger the bug.

If GRO is disabled, no TSO packet ever arrive to the NIC to trigger the
TSO bug ;) So leaving TSO on or off does not really matter.

If GRO is enabled, and TSO disabled, core networking stack will
'segment' the GRO packets right after qdisc dequeue, before giving to
the NIC individual (non TSO) segments.

It enables skb->xmit_more processing on e1000e so you should get better
performance, even if TSO happens to be broken on e1000e



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