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Re: [Xen-devel] Xen cpu usage limting

To: "Brian Wolfe" <brianw@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] Xen cpu usage limting
From: Mark Williamson <Mark.Williamson@xxxxxxxxxxxx>
Date: Fri, 16 Apr 2004 18:17:59 +0100
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxxx
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In-reply-to: Message from "Brian Wolfe" <brianw@xxxxxxxxxxxx> of "Fri, 16 Apr 2004 11:40:05 CDT." <41749.>
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Xen schedules domains on the available CPUs pre-emptively, so CPU usage 
limiting should work just fine.

The default scheduler (BVT) is configured to provide an equal share of a CPU 
to each of the domains running on it.  You can change the weights so that 
domains will get larger or smaller shares (there are some options in 

A single domain shouldn't be able to bog down the others on the system by its 
CPU usage in the default configuration.  In fact, the plan is that disk and 
network usage will also be controllable so that you can give some guarantees 
on the slice of the machine a domain receives.  [I think there are controls in 
place for network, mechanisms for disk are being worked on]  I'll be checking 
in a little documentation about the CPU schedulers next week.  Eventually, we 
should have some kind of "friendly" user interface for controlling them.

To solve your current problem, a little more information would be handy (e.g. 
what release you're using, what scheduler you're using, anything else that's 
odd about the configuration, what configuration the domains have (what is it 
that is consuming 100% CPU in the domain, are the domains sharing any external 
resources that could cause performance problems), anything else you can think 



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