TSO and FreeBSD vs Linux

[Andre Oppermann]

On 15.08.2013 01:27, Kevin Oberman wrote:
> On Wed, Aug 14, 2013 at 12:46 PM, Julian Elischer <julian at freebsd.org>wrote:
>
>> On 8/14/13 3:23 PM, Lawrence Stewart wrote:
>>
>>> On 08/14/13 16:33, Julian Elischer wrote:
>>>
>>>   They switched to using an initial window of 10 segments some time ago.
>>>>> FreeBSD starts with 3 or more recently, 10 if you're running recent
>>>>> 9-STABLE or 10-CURRENT.
>>>>>
>>>> I tried setting initial values as shown:
>>>>     net.inet.tcp.local_slowstart_**flightsize: 10
>>>>     net.inet.tcp.slowstart_**flightsize: 10
>>>> it didn't seem to make too much difference but I will redo the test.
>>>>
>>> Assuming this is still FreeBSD 8.0 as you mentioned out-of-band,
>>> changing those variables without disabling rfc3390 will have no effect.
>>>
>>> I think (check the driver code in question as I'm not sure) that if you
>>> "ifconfig <if> lro" and the driver has hardware support or has been made
>>> aware of our software implementation, it should DTRT.
>>>
>>
>> so I ran on 9.2-beta ( a week or two old) and it had similar problems..
>> only worse.. 9.2 actually sends multiple packets when is doesn't need to..
>>      http://people.freebsd.org/~julian/fbsd9.png
>>
>
> Ack! (Sorry) I could have sworn that this had been fixed. Has it been
> re-broken?

There may be some window update dynamics going on together with LRO received
ACK compression.

-- 
Andre