Horrendous upload network performance with VLAN (download seems OK)

[Adrian Chadd]

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 at sarenet.es> wrote:
>
> On Dec 3, 2014, at 5:21 PM, Patrick Proniewski wrote:
>
>> On 3 déc. 2014, at 17:09, Borja Marcos <borjam at 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 changes.
>>>
>>> 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, depending 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 bxe0 that shows a lot of packets for the LLC protocol, and one on bxe0.161 that 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 again 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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