TSO and FreeBSD vs Linux

[Julian Elischer]

On 8/22/13 1:12 AM, Andre Oppermann wrote:
> On 13.08.2013 19:29, Julian Elischer wrote:
>> I have been tracking down a performance embarrassment on AMAZON EC2 
>> and have found it I think.
>> Our OS cousins over at Linux land have implemented some interesting 
>> behaviour when TSO is in use.
>
> There used to be a different problem with EC2 and FreeBSD TSO. The 
> Xen hypervisor
> doesn't like large 64K TSO bursts we generate, the drivers drops the 
> whole TSO chain,
> TCP gets upset and turns off TSO alltogether leaving the connection 
> going at one
> packet a time as in the old days.
>
> The problem is already fixed in recent EC2 9-stable images provided 
> by cperciva.
>
yes we have those fixes.