Re: [Xen-users] Increasing throughput on xen bridges

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

>   I have a rhel 5.1 xen server with two rhel 3 ES hvm guests installed.
> Both rhel3 guests use an internal xen bridge (xenbr1) which it isn't binded
> to any physical interface host. On this bridge throughput it is very very
> poor, only 2.5 Mbs. How can I increase this throughput???

The bridge driver does add overhead but I suspect that your poor performance 
is more likely due to the HVM emulation of the network card than the bridge 
driver.

If there's a Linux 2.6 kernel available for RHEL 3, you might be able to 
compile the PV drivers from the "unmodified_drivers" directory in the Xen 
tree.  These would improve performance.

There were some patches posted to the list from Virtual Iron that enabled PV 
drivers to be used under a Linux 2.4-based kernel, which would enable you to 
compile against a 2.4 kernel in your HVM machine.

The above suggestions would mean that you keep using a RHEL3 kernel in the HVM 
virtual machine but just add PV drivers.

Finally, http://xen.org/download/dl_304guest_rhel3.html contains a download 
link for a Xen-patched 2.4.21 kernel for RHEL 3.8.  This is not an official 
RedHat supported kernel, since it's been patched by XenSource.  Therefore it 
could perhaps impact your support agreement...  But if you converted to a PV 
domain using it you might improve performance, particularly for network.

This suggestion differs in that you would actually be converting from using an 
HVM domain to using a PV domain with an entirely different kernel.

Cheers.
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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