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Re: [Xen-users] Why limit dom0's memory?

To: "Gastón Keller" <gastonkeller@xxxxxxxxx>
Subject: Re: [Xen-users] Why limit dom0's memory?
From: "Alain Barthe" <ab266061@xxxxxxxxx>
Date: Mon, 16 Jun 2008 09:29:44 +0200
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2008/6/14 Gastón Keller <gastonkeller@xxxxxxxxx>:
---------- Forwarded message ----------
From: Gastón Keller <gastonkeller@xxxxxxxxx>
Date: Sat, 14 Jun 2008 08:34:56 -0400
Subject: Re: [Xen-users] Why limit dom0's memory?
To: "Sandor W. Sklar" <ssklar@xxxxxxxxxxxx>

On 6/14/08, Sandor W. Sklar <ssklar@xxxxxxxxxxxx> wrote:
>
> Could someone explain why it is recommended to limit the amount of
> memory on the Dom0 via setting dom0_mem=XXX in grub.conf?  Are there
> situations where the dom0 would grab onto more memory then it needs?

Here the reason we set the "dom0_mem" in grub.conf is very precise : without it the 12 domUs autostarted have problems at startup, looked like the dom0 had not time enough to correctly ballon out memory for domUs. By setting in advance the dom0 memory, no more problem (note that the problem occured only when a lot of domUs are created simultaneously).
 

AFAIK what some people is doing is setting a level of memory for Dom0
for it to never go down that level (giving memory to the guests). That
is, if you set the memory to 1 GB, Dom0 will allocate all your memory
except for that 1 GB. It's a way of ensuring that Dom0 will never run
out of memory.

I don't think so. The minimum memory for dom0 is defined through the "dom0_min_mem" parameter in the xend-config.sxp file.
 


 Gaston
>
> Thanks,
>       -s-
>
>
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>


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