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Re: [Xen-users] Questions on memory allocation

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Subject: Re: [Xen-users] Questions on memory allocation
From: "Ryan Burke" <burke@xxxxxxxxxxxxxxxxx>
Date: Tue, 30 Oct 2007 14:19:31 -0500 (CDT)
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Take a look at this:


It seems to answer what he maxmem config parameter and xm max-mem command
do. I haven't played with the memory allocation of DomU's.

Personally I always though the balloon driver was the fact that you could
allocate all the system's RAM to the Dom0 then as you allocated to other
DomU's it would deflate Dom0's memory accordingly. That way you are
potentially getting use from all your RAM instead of locking Dom0 to a
small slice when it could be using more for better performance. Of course
there always seemed to be issues with people trying to squeeze Dom0 too
small by not giving it a large enough "min-mem" setting.


> On Tue, 30 Oct 2007, in a new attempt to enlighten us, Ryan Burke wrote:
> RB> Javier,
> RB>
> RB> Xen does not dynamically adjust the amount of memory a DomU has
> available.
> RB> In the configuration you've mentioned the DomU's will have 128 MB of
> RB> and you can manually adjust that up to 1024 MB of RAM using the
> "mem-set"
> RB> command.
>   But then, what's the use of setting a 'mem-max' value? If you grow the
> domU memory manually, mem-max is... what? a sort of "preassure valve"? If
> you try to allocate more memory to the domU than "mem-max", it just
> caps you and give you an error?
>   If this is the use, can anybody give me examples of WHEN and WHERE to
> use it, as I can't figure them out?
>   Regarding the "balloon driver": was it dropped? Some posts seems to
> state that, though I couldn't find further info about this.
>   And the values in /proc/xen/balloon? Can they be used with to create an
> script to allocate memory "sort of" automagically?
>       Saludos
>                 Javier, a.a.t.
> --
>    "I had such a crush on her. Until I met you Lois, you're my silver
>  medal."
>                                            (Peter Griffin, "Family Guy")

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