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Re: [Xen-devel] [PATCH] Make "xm mem-set" be lower bound on domX-min-mem

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] Make "xm mem-set" be lower bound on domX-min-mem
From: Gareth S Bestor <bestor@xxxxxxxxxx>
Date: Sat, 20 May 2006 14:27:49 -0700
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>...shrinking to <2% of original allocation is a very bad idea

An absolute limit might be easier to handle - and expose to users - than a relative one, especially up-front in CIM where it exposes min/max limits on resource allocations. Or is it really <2% of whatever the original memory allocation is when things go to kabluwey... ?

BTW - at the moment we are exposing a 16MB minimum DomU memory size thru our CIM providers resource allocation defaults, although this is more a hint than anything actually enforced; the mgmt client can still pass in whatever value they like and we (CIM) will blindly pass it along to xm create ...

- Gareth

Dr. Gareth S. Bestor
IBM Linux Technology Center
M/S DES2-01
15300 SW Koll Parkway, Beaverton, OR 97006
503-578-3186, T/L 775-3186, Fax 503-578-3186

Inactive hide details for Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>

          Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>

          05/20/06 01:26 AM


Gareth S Bestor/Beaverton/IBM@IBMUS




Re: [Xen-devel] [PATCH] Make "xm mem-set" be lower bound on domX-min-mem

>  Unless there is an known *architectural* limit in Xen on the lower
> bound of the memory for a guest DomU, then I agree - xend
>  shouldn't impose an arbitrary one simply to act as 'hard hint' to
> prevent stupid users from doing stupid things
>  (give 'em all the rope they want I say! :-) Care-and-feeding of naive
> users is best left to tools higher up the mgmt stack (IMO).

I agree with this. I'm also not sure about putting a lower bound in the
balloon driver, but at least there we know that shrinking to <2% of
original allocation is a very bad idea with very high probability.

 -- Keir

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