netdev - RE: [PATCH net-next 0/5] qed/qede: Tunnel hardware GRO support

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Date:	Thu, 23 Jun 2016 09:03:12 +0000
From:	Yuval Mintz <Yuval.Mintz@...gic.com>
To:	Rick Jones <rick.jones2@....com>,
	Eric Dumazet <eric.dumazet@...il.com>
CC:	Alexander Duyck <alexander.duyck@...il.com>,
	Manish Chopra <manish.chopra@...gic.com>,
	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	Ariel Elior <Ariel.Elior@...gic.com>,
	Tom Herbert <tom@...bertland.com>,
	Hannes Frederic Sowa <hannes@...hat.com>
Subject: RE: [PATCH net-next 0/5] qed/qede: Tunnel hardware GRO support

> > My systems are presently in the midst of an install but I should be
> > able to demonstrate it in the morning (US Pacific time, modulo the
> > shuttle service of a car repair place)
> 
> stack@...cp1-comp0002-mgmt:~$ ./netperf -H np-cp1-comp0001-guest -- -G
> 1400 -P 12867 -O throughput,transport_mss MIGRATED TCP STREAM TEST from
> 0.0.0.0 (0.0.0.0) port 12867 AF_INET to np-cp1-comp0001-guest () port 12867
> AF_INET : demo Throughput Transport
>             MSS
>             bytes
> 
> 3372.82    1388
...
> root@...cp1-comp0001-mgmt:/home/stack# tcpdump -n -r foo.pcap | fgrep -v
> "length 0" | awk '{sum += $NF}END{print "Average:",sum/NR}'
> reading from file foo.pcap, link-type EN10MB (Ethernet)
> Average: 2741.93

Yes, it's a known FW limitation - if MSS is smaller than configured MTU,
aggregation will be closed on 2nd packet; It might get changed in some future
FW version. But I agree it reinforces the need of having some kind of
user-knob for controlling this offloaded feature.