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Re: [Xen-users] how much memory does the hypervisor need

Subject: Re: [Xen-users] how much memory does the hypervisor need
From: Thomas Goirand <thomas@xxxxxxxxxx>
Date: Wed, 18 Feb 2009 12:55:34 +0800
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Philipp Schmid wrote:
> so if i take the 16384mb of ram minus the used space and the space xen
> sys it still has i get:
> 16384 - 14037 - 1930744/1024 ~= 461.5mb
> does the hypervisor really need 460mb of memory?
> is there a way to calculate how much memory the hypervisior needs?
> lg philipp

There is no need to do such calculation. Type "xm info" and it will tell
you how much memory you have left. But anyway, I don't think that Xen is
wrong when it tells you there is not enough RAM left.

If you wish to resize the dom0, you can do like this:

xm mem-set Domain-0 384

This will set your dom0 with 384 MB of RAM, which is quite enough if you
don't run too many things in the dom0. At the time of xen 2.0.7, with
sarge, we used to set 128 MB of RAM, and it was quite ok. Now, with
newer operating systems, 384 MB seems to be a reasonable value with
which we never have issues (note that we set 512 MB of swap).

As said Gary, a good idea is to set the dom0 memory footprint in your
grub config, and/or NOT let it baloon out too much (for example by
setting the minimum in xend-config.sxp).

Best Regards,

    Thomas Goirand

Thomas Goirand
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