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Date: Fri, 23 Aug 2013 16:21:29 +0800
From: Julian Elischer <julian@freebsd.org>
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To: Andre Oppermann <andre@freebsd.org>
Subject: Re: TSO and FreeBSD vs Linux
References: <520A6D07.5080106@freebsd.org> <5214F506.3070706@freebsd.org>
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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.