[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Re: [PATCH][BALLOON] Fix minimum target
> The idea was to have in place a structure that allowed for some > experimentation on exactly what the floor needs to be and what the > minimum memory slope needs to be. An earlier version of my patch > attempted to classify machines based on the maximum amount of memory > that it would ever handle. For each class the minimum memory was still a > linear function with the slope and the floor being dependent on the > maximum amount of memory that the domain would handle. Another approach > I was considering was to base the amount of minimum memory on the amount > of free memory a domain has. This strategy may give us a reasonably > functional system when the domain is ballooned down while it may result > in a minimum that could be potentially higher than an approach that we > have been playing with might yield. I don't believe any static predetermined floor is going to work well. Basically I expect that any such approach will either: A. Exhibit many false negatives (allow ballooning beyond the critical point and result in OOM) B. Exhibit many false positives (disallow ballooning when it would actually be safe) C. Be an unmaintainable mess of special cases derived via empirical analysis that will not scale or continue to work well moving forward I'm particularly bothered by B as it is harder to prove that a particular patch has that problem. But for example, I'm sure a static floor of 192MB falls squarely into B. Unless someone convinces me otherwise, I hold out more hope for the kind of dynamic approach I've been discussing with Aravindh. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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