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Re: [Xen-users] NIC Offloading Confusion

On Fri, Apr 24, 2009 at 8:13 PM, Robert Dunkley <Robert@xxxxxxxxx> wrote:
> Hi Fajar,
> These are HVM guests with PV Drivers:
> DOM0 is Centos 5.2 with Xen 3.31
> DOMU is Centos 5.3 using integrated PV Drivers

Ah, I see.
Is there a particular reason to use HVM?
Unless you're using some propietary binary-only kernel module, you'll
have much better results using PV guests. Converting HVM to PV guest
is pretty straightforward. I can share the steps if you're interested.

> The problem seems to be gone with all offload disabled on the bridge and
> DomU but rx, tx and scatter enabled on the physical NIC.
> The problem is very noticeable, about 5-10 seconds after turning on an
> offload it does not like the SMTP and DNS service on the DOMU begin to
> slow. I wonder if this is the Intel driver included with Centos 5.2 that
> causes the problem:
> filename:
> /lib/modules/2.6.18-92.1.6.el5xen/kernel/drivers/net/e1000e/e1000e.ko
> version:        0.2.0
> license:        GPL
> description:    Intel(R) PRO/1000 Network Driver
> author:         Intel Corporation, <linux.nics@xxxxxxxxx>
> This version looks very old (Latest is but Centos 5.3 seems to
> use the same version, I'm not sure how I'm meant to update this driver,
> some sources say it requires a kernel rebuild but others like the link
> below show it as a simple install:
> http://downloadcenter.intel.com/filter_results.aspx?strTypes=all&Product
> ID=2248&OSFullName=Linux*&lang=eng&strOSs=39&submit=Go%21

I suggest you try it if possible. It's usually pretty simple (and MUCH
easier if you can find a dkms version).

On early RHEL 5.0 series I had to recompile tg3 modules manually since
RHEL's driver was having problems. The result was well worthed the

> Can you think of any reason why the included Redhat driver is so old?

I don't know. Possible licensing issue, or that the new version is not
tested enough.

Good luck.



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