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Re: [Xen-users] Re: [quagga-users 10973] Quagga on Xen - Latency / Bandw

To: Alexis Rosen <alexis@xxxxxxxxx>
Subject: Re: [Xen-users] Re: [quagga-users 10973] Quagga on Xen - Latency / Bandwidth?
From: Pasi Kärkkäinen <pasik@xxxxxx>
Date: Wed, 29 Jul 2009 16:09:48 +0300
Cc: Quagga-users@xxxxxxxxxxxxxxxx, Xen User-List <xen-users@xxxxxxxxxxxxxxxxxxx>, Robert Dunkley <Robert@xxxxxxxxx>
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On Wed, Jul 29, 2009 at 04:52:47AM -0400, Alexis Rosen wrote:
> On Jul 29, 2009, at 4:04 AM, Robert Dunkley wrote:
> >I was wondering if anyone is running Quagga on Xen? What is
> >throughput/latency like?
> >
> >Was looking for about a gig of mixed packet size BGP throughput.
> Presumably you mean internet traffic.
> On bare metal (no Xen), that will work fine for mixed Internet  
> traffic, but you need to think about corner cases. What do you expect  
> to have happen when you get DDoSed with minimum-size packets? I don't  
> think even the multiqueue GbE cards will let you handle that, but I  
> have not tested that, and I'd love to be proven wrong.
> I'm also under the impression that Linux 2.6.30 kernels have some  
> significant patches to make (better?) use of multiqueue cards but I  
> don't remember the details. Maybe 2.6.30 can distribute ksoftirqd load  
> over multiple cores? If so that's a big win, as that was the killer  
> with large PPS when we tested on somewhat less powerful hardware with  
> an older kernel, and you can probably handle a full gbps of min-sized  
> packets if you give it a number of cores (and you have enough queues).

Here's some recent thread on lkml about linux 10 gbit routing performance:

"We also achieved nearly 80 Gbps in bidirectional TCP tests (40 Gbps
simultaneously in each direction):"

But that was on baremetal.

> Another question to think about (sorry, no answers here, just  
> questions): If you do run under Xen, is there interrupt load in both  
> the dom0 and the domU? In that case you'll get pounded. Maybe  
> dedicating an entire Ethernet port to the domU is a way to work around  
> that. I know Xen3 has provisions for that sort of thing but I haven't  
> used it.

Other link about Xen network performance with Solarflare 10 Gbit
"Accelerated" NIC:


-- Pasi

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