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Date:      Wed, 29 Jul 2015 07:47:28 +0100
From:      Karl Pielorz <kpielorz_lst@tdx.co.uk>
To:        xen@FreeBSD.org
Subject:   Poor network performance with Xen + OpenVPN?
Message-ID:  <B314E8002A8A1A7A537DB661@Karls-Mac-mini.local>

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Hi All,

A while ago I ran into an issue with FreeBSD + Xen and networking (where 
FreeBSD PVHVM domU's can't "route" traffic to/from other domU's 
(fbsd/linux/windows) - e.g. as a default gateway).

I seem to have run into what appears to be another network issue now  - 
XenServer 6.5-SP1 +hotfixes, with FreeBSD 10.1-p4 (as PVHVM), and OpenVPN 
2.3.7

Everything 'works OK' - but the performance is pretty poor. Most noticeable 
- if you have a browser open fetching pages via the VPN - the pages arrive 
very slowly, and any ssh sessions etc. are instantly put on a 'go slow', 
you also start getting ping timeouts when pinging hosts the other side of 
the VM/VPN until the pages are fetched.

Swap back to a bare metal system (on the same networks) - it works fine, 
switch back over to the VM - and again, performance is lousy.

The host running OpenVPN isn't really under any load (it's only job is 
running OpenVPN) - nor is it's XenServer.

If I connect to another OpenVPN host which is running on an HVM FreeBSD 9.1 
domU - performance is indistinguishable from the bare metal (as you'd 
expect considering the relatively low volumes of traffic over the VPN etc.)

Can anyone suggest any fixes / where to look to try and keep it as PVHVM, 
and get the performance back? - as we've already got a collection of HVM 
machines (to work round the other network problem) - which I don't really 
want to add to, as they're not agile :(

Cheers,

-Karl



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