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RE: [Xen-devel] Re: Xenheap disappearance: (was:xen_phys_startfor32b)

To: "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx>, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx>
Subject: RE: [Xen-devel] Re: Xenheap disappearance: (was:xen_phys_startfor32b)
From: "Jan Beulich" <jbeulich@xxxxxxxxxx>
Date: Tue, 20 Jan 2009 09:11:30 +0000
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>>> Dan Magenheimer <dan.magenheimer@xxxxxxxxxx> 19.01.09 21:04 >>>
>> as I frequently see systems with completely empty domain heaps.
>
>Really?  Oh, I see we probably have different default paradigms
>for memory allocation.  On Oracle VM, dom0 is by default
>launched with 256MB and all remaining memory is "free" and
>guests are generally launched with memory==maxmem.  As a
>result, it is very unusual to have an empty domheap due
>to fragmentation.
>
>I expect you are running without dom0_mem unset, thus
>using auto-ballooning from dom0 by default.  And probably
>either guests are usually launched with memory<<maxmem or
>are using disk='file:...' (which results in dom0 filling
>up its page cache) or both.  True?

All of this indeed is correct for default SuSE installations, and close to
correct for my private way of setting up things (I do use dom0_mem,
but only to avoid auto ballooning for starting a single, average size VM,
as I rarely find myself running more than one at a time).

>> *must* be accompanied by a tools change in order to be usable
>
>Yes, I see that it would be a must for your different paradigm,
>but less important in the one I am accustomed to.

Since there's no dom0_mem used by default in -unstable, the 'must'
applies there too.

Jan


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