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[Xen-ia64-devel] Re: [Xen-devel] [PATCH] Fix auto-ballooning of dom0 for

On 22 May 2006, at 16:15, Charles Coffing wrote:

Where does the slack from the previous HVM guest startup go? Are you

saying that dom0 only frees up PV- guest- size minus existing-


Unless, of course, the HVM domain has eaten up some of the slack in the
mean-time, in which case dom0 frees up PV-guest-size minus

The auto-ballooning logic is shagged then. xend should keep track of memory requirements (inc. max overheads) of every domain, then ensure dom0 memory usage is no greater than total memory minus sum of all other domains' memory requirements. How hard can that be? (Too hard for original author I guess ;-) ).

Anyway, I'm going to back out the "4MB slack" hack. Auto-ballooning can never be stable in its current form (consider a guest that temporarily balloons down from 128MB to 64MB, then another (HVM) guest starts, then it tries to balloon back to 128MB -- it'll fail, and the HVM guest will lose any headroom it required).

 -- Keir

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