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Re: [Xen-users] Retrieving the load of each domU

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Retrieving the load of each domU
From: Mark Williamson <mark.williamson@xxxxxxxxxxxx>
Date: Mon, 27 Mar 2006 16:24:34 +0000
Cc: Ugo PARSI <ugo.parsi@xxxxxxxxx>
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> I'm trying to get the load (average load or CPU usage) of each domU in
> order to script a load balancing solution.... how can I retrieve this
> information from a text command or from an interface structure ?
>
> The only thing that seems to work is the 'xm-top' command, with the
> cpu percentile, which is curses based and so this is quite hard to
> parse...

Easiest is to ssh to the guest and run "free" or "vmstat", or you can install 
a network monitor tool.

Bear in mind that even though you can't trust a guest in general to report 
usage stats, you equally can't trust a guest not to just fake high activity 
(by doing loads of random disk IO / allocing loads of memory) and causing 
even trusted tools to report that the guest needs more space.  You just can't 
tell if what the guest is doing is genuinely useful work.

It's probably sensible to trust reports from the guest, at least initially, 
but have some limits on auto-ballooning to limit starvation to other guests 
until the admin checks up on what's happening.

HTH,
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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