Re: [Xen-users] Bad TCP accept performance

[Iain Kay <spam@xxxxxxxxxxx>]

Oh I see. My apologies I had not seen any mention of the newer kernels however I did just glance over the post this morning so that could have been why.

I think the fact you have results from people doing the testing on dom0 showing similar drop in performance probably means it's unlikely that Guest OS configuration alone will sort it out.

However I am hopeful, and as soon as I have finished up in work I'll play with 2.6.39 and post up results.

Iain

On 25 May 2011, at 11:55, Carl Byström wrote:

2011/5/25 Iain Kay <spam@xxxxxxxxxxx>

None of your Xen tests where performed on a suitably recent kernel... KVM was performed on 2.6.38.6 kernel whereas Xen was performed on 2.6.32... Fair difference. Kernel development has been pretty active lately and I would not be surprised if you see major differences between older and newer kernels when using for virtualisation.

I've tried on EC2 using a 2.6.38 kernel (Ubuntu 11.04 Natty 32-bit, AMI ami-e2af508b), same results there.

Someone also submitted a report from Linode with kernel 2.6.38-x86_64.

 

I'm attempting to install Xen on top of 2.6.39 vanilla kernel today. Will run your tests on my box and see what the results are...

Please do.

 

Quite disheartening to see such a drop in accept performance, I for one hope it's just misconfiguration (or requires further configuration) to bring the VMs up to spec.

Yes, I hope so. At least I hope for the possibility to mitigate this by some guest OS tuning (but I'm starting to think that's a bit naïve).

 

--

Carl

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