kern/154428: xn0 network interface and PF - Massive performance drop

[Alex]

The following reply was made to PR kern/154428; it has been noted by GNATS.

From: Alex <joovke at joovke.com>
To: Cc: freebsd-xen at freebsd.org, bug-followup at freebsd.org
Subject: Re: kern/154428: xn0 network interface and PF - Massive performance
 drop
Date: Mon, 14 Feb 2011 23:07:29 +1100

 I stumbled across PR 135178, perhaps there is some relationship with 
 these PR's, though the reporter of that PR has not responded in some time.
 
 On 02/13/11 15:31, Colin Percival wrote:
 > On 02/12/11 20:18, Alex wrote:
 >> Fixed by net.inet.tcp.tso: 1 ->  0
 >>
 >> but why?? found this by trial an error.  setting net.inet.tcp.tso to 0
 >> with pf enabled gives good performance, if i set it to 1, speeds plumet
 >> to below dialup!
 > There have been problems with Xen and TSO in the past relating to how much
 > data gets handed off to the hypervisor at once... why this would cause issues
 > only with PF, I have no idea, though.
 >