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Date:      Wed, 3 Dec 2014 08:27:08 -0800
From:      Adrian Chadd <adrian@freebsd.org>
To:        Borja Marcos <borjam@sarenet.es>
Cc:        FreeBSD Net <freebsd-net@freebsd.org>, Steven Hartland <killing@multiplay.co.uk>, Patrick Proniewski <patpro@patpro.net>
Subject:   Re: Horrendous upload network performance with VLAN (download seems OK)
Message-ID:  <CAJ-Vmom7F-8Euk%2BUyiBXxzSrmfuvnqTjfCrkVOcZ205fg=4NvA@mail.gmail.com>
In-Reply-To: <F537F496-27F4-4E31-850A-641C8F3719AC@sarenet.es>
References:  <727AB395-CF83-4D13-A2C3-50969C2969B0@patpro.net> <547F3352.3040101@multiplay.co.uk> <43C2162E-2B9F-437F-B4CF-E792CEC5DA7B@patpro.net> <DC8D5BD7-8743-4AB9-952B-54822723610D@sarenet.es> <E3234CED-CEB4-48AF-B3F9-1492AFF4DB46@patpro.net> <F537F496-27F4-4E31-850A-641C8F3719AC@sarenet.es>

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hi,

try dropping the MSS of the connection down.

I wonder if you're hitting some frame size cap when transmitting -
adding a VLAN header adds a few bytes to the size of the frame. If the
NIC is enforcing some maximum frame transmit size then it may be
failing to transmit things.



-adrian


On 3 December 2014 at 08:25, Borja Marcos <borjam@sarenet.es> wrote:
>
> On Dec 3, 2014, at 5:21 PM, Patrick Proniewski wrote:
>
>> On 3 d=C3=A9c. 2014, at 17:09, Borja Marcos <borjam@sarenet.es> wrote:
>>
>>> On Dec 3, 2014, at 5:05 PM, Patrick Proniewski wrote:
>>>
>>>> I did and it failed, but maybe I've not used the right syntax:
>>>>
>>>>     # ifconfig bxe0 -vlanmtu
>>>>     ifconfig: -vlanmtu: Invalid argument
>>>>
>>>> man bxe makes me think that this driver won't allow this kind of chang=
es.
>>>
>>> Although there's no guarantee it will solve your issues, try disabling =
LRO and TSO. I've found situations in which they do more harm than good, de=
pending on the particular card and driver.
>>>
>>> Anyway it's a cheap experiment :)
>>
>> Sure.
>> Same result unfortunately.
>>
>> I've made few tcpdump experiments during my scp upload tests. One on bxe=
0 that shows a lot of packets for the LLC protocol, and one on bxe0.161 tha=
t shows many "suspected TCP retransmissions", and very few LLC packet (6 in=
 about 350 packets of this capture).
>
> I forgot, sorry. Sometimes you need to set the interface to down and up a=
gain to make sure changes to flags such as LRO and TSO have been applied :/
>
> TSO can be disabled in a global way using a sysctl variable: net.inet.tcp=
.tso
>
>
>
>
>
> Borja.
>
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