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[Xen-devel] Re: [PATCH][BALLOON] Fix minimum target

On 27 May 2006, at 21:34, Puthiyaparambil, Aravindh wrote:

Dom0 needs a much bigger floor of 192M. I think this is where KY came up with the 192M number. I know this will cause problems on machines coming
up with dom0_mem<192M.

That being the case (which it certainly is) it is pretty obvious that a floor of 192M is not suitable in all situations.

Both these options will break xm-test. So how do you want to proceed?

If there isn't a suitable static minimum which prevents OOM death on most systems without also impacting the useful lower range of ballooning on other systems then I think we'll have to wait for someone to implement a more dynamic scheme (e.g., by hooking off the OOM/low-memory paths, or by slowly allocating memory only when we can see a reasonable amount of pages available on the free lists).

I'm rather doubtful that a really good static estimate can be derived, since it depends so much on particular details of kernel memory usage. Given the results of these experiments I'm tempted to remove the 2% minimum that is already in the tree -- vendors can make their own patch if they have a better idea of what works for their particular kernel setups.

 -- Keir

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