Hosting improvements - more, more, more - pascal

pascal — Mon, 02 Mar 2009 14:52:41 +0100

Hi,

Yes, driver domain has guaranteed ressources for virtual I/Os.

Today xen is configured with strict (credit) partitionning, equally important domains.
You get a fixed amount of credit with each share.

However, we do not want the share to appear excellent at the beginning (because you're alone on a node, you get full idle cpu for yourself) and degrade over time with no user idea of when it will stabilize. As people can try our servers "for a few minutes", that would be kind of lying. We want the user to experience an expected, stable performance level.

So we slightly overcommit on the credit, and as we'll get better at migrating vms accross nodes to achieve a little balance, we'll probably overcommit a little more.

Hosting improvements - more, more, more - Anonymous

Anonymous — Sun, 01 Mar 2009 20:32:59 +0100

Your data about CPU utilization reminds me of a couple of questions I have about Gandi's hosting service.

Do you have Xen configured to strictly partition CPU resources and not allow domains to exceed them, or can one domain take more CPU if another domain falls idle? The latter seems like a better way to ensure that CPUs stay near 100% utilization at all times.

Also, given how Xen does virtual I/O through domain 0, you should have Xen configured so that domain 0's VCPUs get dedicated physical CPUs which nothing else can run on. This will significantly improve I/O performance.

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Hosting improvements - more, more, more - pascal

Hosting improvements - more, more, more - Anonymous