RE: [Xen-devel] questions about mem-max

To:	"Li Ge" <lge@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject:	RE: [Xen-devel] questions about mem-max
From:	"Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>
Date:	Thu, 1 Sep 2005 00:11:18 +0100
Delivery-date:	Wed, 31 Aug 2005 23:09:15 +0000
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Thread-topic:	[Xen-devel] questions about mem-max

> I am trying to understand how the command "xm mem-max" works 
> and write some testcases for it. Here are some confusion I have:
> 
> 1. Can maximum memory be adjusted for a domain at runtime by 
> using 'xm mem-max'? Right now, I see that the max memory 
> change made by 'xm mem-max' is only recorded by xend. There 
> is no change in /proc/xen/balloon and /proc/meminfo.
> 
> 2. If the answer to 1 is no, how to activate the change to 
> the domain? How should I verify it?

max-mem isn't really intended as a user command. It doesn't really
server any purpose in a world with well-behaved VMs. What probably
should happen is that when balloning a domain down in size, xend should
periodically poll the domain's memory usage and set max-mem to be the
current usage plus some small slack. This would prevent a runaway domain
ignoring its memory target and trying to grow its allocation.

Ian 

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