Re: [Xen-users] xm top shows high CPU load on domU when passed PCI NICs after hypervisor update

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Fri, Jul 27, 2012 at 09:39:23AM +0100, Ian Campbell wrote:
> On Thu, 2012-07-26 at 21:26 +0100, Beanjammin H wrote:
> > I am running a 64 bit dom0 with a stock Debian Squeeze xen hypervisor
> > and kernel.  On top of this I am running a PV 32 bit domU that is
> > passed two PCI network cards.  This set-up had been working well for
> > over a year, however there was a recent hypervisor update so I
> > rebooted the dom0.  Unfortunately now the domU that is being passed
> > the two NICs is no longer able to create a PPPoe connection to my ISP
> > and xm top show's it's CPU use consistently at 100%.  Suggestions on
> > what I can do to trouble shoot this would be appreciated.  Here is
> > what I have tried to date:
> > 
> > - Revert the hypervisor update (packages
> > libxenstore3.0_4.0.1-4_amd64.deb
> > xen-hypervisor-4.0-amd64_4.0.1-4_amd64.deb
> > xenstore-utils_4.0.1-4_amd64.deb xen-utils-4.0_4.0.1-4_amd64.deb
> > xen-utils-common_4.0.0-1_all.deb) and reboot the dom0, but this
> > doesn't seem to make any difference, so perhaps the timing was a
> > coincidence or I've missed reverting a package.
> 
> You might also need to try reverting any dom0 kernel updates which
> happened in the interim as well?
> 
> Likewise domU.
> 
> > Searching through the mailing list and google in general hasn't turned
> > up reports of a simliar issue.
> 
> There was one performance issue relating to swiotlb and bounce buffering
> not so long ago. I'm hoping that Konrad (CCd) will remember the details.

It was an optimization:

commit 6810df88dcfc22de267caf23eb072ffb97b3c411
Author: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date:   Thu Aug 25 16:13:54 2011 -0400

    xen-swiotlb: When doing coherent alloc/dealloc check before swizzling the 
MFNs.
    

> 
> What are the exact dom0 and domU kernel versions?
> 
> > Any suggestions would be greatly appreciated.
> > 
> > - Ben
> > 
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@xxxxxxxxxxxxx
> > http://lists.xen.org/xen-users
> 

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