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RE: [Xen-users] Lots of udp (multicast) packet loss in domU


  • To: "Mike Kazmier" <DaKaZ@xxxxxxxxx>, <xen-users@xxxxxxxxxxxxxxxxxxx>
  • From: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
  • Date: Fri, 16 Jan 2009 10:44:45 +1100
  • Cc:
  • Delivery-date: Thu, 15 Jan 2009 15:45:57 -0800
  • List-id: Xen user discussion <xen-users.lists.xensource.com>
  • Thread-index: Acl3M2ryKcJRUdgiQMKl9c0HcXEvRAAN4Ucw
  • Thread-topic: [Xen-users] Lots of udp (multicast) packet loss in domU

> 
> Our physical eth3 is connected to xenbr2 which is used to send info to
the
> domU.
> 
> > Hmmm... well if you have 600Mbps traffic of 1316 bytes per packet,
that
> > is ~60Mbytes/second / 1316 bytes = ~45000 packets per second.
> >
> > While things are going at 600Mbps, please try the following in both
Dom0
> > and DomU:
> >
> > cat /proc/interrupts && sleep 10 && cat /proc/interrupts
> >
> > That should get a very approximate count of interrupts over a 10
second
> > period. what is the difference (after - before) for:
> >
> > Dom0 physical Ethernet interface
> > Dom0 vif (backend) interface
> > DomU eth0
> 
> Dom 0
> 36: 14136682 0 Phys-irq-level eth3, eth4
> 36: 14176719 0 Phys-irq-level eth3, eth4
> Diff: 40037
> 
> 275: 254326 0 Dynamic-irq-level vif8.2
> 275: 259086 0 Dynamic-irq-level vif8.2
> Diff: 4760
> 
> Dom U
> 277: 1105308 0 0 0 0 Dynamic-irq eth2
> 277: 1147909 0 0 0 0 Dynamic-irq eth2
> Diff: 42601
> 

So Dom0 is getting around 4000 interrupts a second, and DomU is getting
around 4200 interrupts a second, so it sounds like both are doing
interrupt moderation, which is good.

I notice that eth3 and eth4 are both sharing an interrupt. Is eth4
active during this time?

James

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