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Re: [Xen-devel] [PATCH] Network Checksum Removal


  • To: Andrew Theurer <habanero@xxxxxxxxxx>
  • From: Bin Ren <bin.ren@xxxxxxxxx>
  • Date: Mon, 23 May 2005 16:56:53 +0100
  • Cc: Xen-devel@xxxxxxxxxxxxxxxxxxx, Jon Mason <jdmason@xxxxxxxxxx>
  • Delivery-date: Mon, 23 May 2005 15:56:18 +0000
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  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>

I'm using bridge and stock scripts. I start to doubt it's caused csum
offloading, as I'm seeing some weird things. (1) it's possible to do
interdomain iperf, which binds to ports > 1024 (2) ssh and nfs don't
work. In both cases, dom0 is the server, dom1 is the client. tcpdump
on dom0 doesn't show any incoming packets from dom1.

I'm recompiling everything again.

Cheers,
Bin

On 5/23/05, Andrew Theurer <habanero@xxxxxxxxxx> wrote:
> On Monday 23 May 2005 10:31, Bin Ren wrote:
> > It seems to break the interdomain ssh and nfs on my machine. Digging
> > for reasons.
> 
> Are you using bridge or network model?
> >
> > - Bin
> >
> > On 5/23/05, Andrew Theurer <habanero@xxxxxxxxxx> wrote:
> > > > I've checked in a modified version of your patch that hopefully
> > > > deals with propagating checksum information in both directions
> > > > across a virtual bridge or router. I replaced your skb flags with
> > > > two new ones -- proto_csum_blank and proto_csum_valid.
> > > >
> > > > The former indicates that the protocol-level checksum needs
> > > > filling in. This is not a problem for local processing, but the
> > > > flag is picked up before sending to a physical interface and
> > > > fixed up.
> > > >
> > > > The latter indicates that the proto-level checksum has been
> > > > validated since arrival at localhost (*or* that the packet
> > > > originated from a domU on localhost). This flag survives crossing
> > > > a bridge/router so we can trust it when deciding if checksum
> > > > validation is required.
> > > >
> > > > I'll push the patch to the bkbits repository just as soon as
> > > > bkbits rematerialises. :-)
> > > >
> > > > If you have any performance or stress tests that you were using
> > > > to test checksum offloading, it would be great to find out how
> > > > they perform on the checked-in version!
> > >
> > > Now that BK is up, I'll run some netperf tests before/after that
> > > changeset and see what we get.
> > >
> > > -Andrew
> > >
> > > _______________________________________________
> > > Xen-devel mailing list
> > > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > > http://lists.xensource.com/xen-devel
> 
>

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