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Date: Wed, 21 Aug 2013 19:12:38 +0200
From: Andre Oppermann <andre@freebsd.org>
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To: Julian Elischer <julian@freebsd.org>
Subject: Re: TSO and FreeBSD vs Linux
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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.

-- 
Andre