[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] RFC: large system support - 128 CPUs
On 13/8/08 09:47, "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx> wrote: > On 13/8/08 09:45, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote: > >> But the cpumask-in-page_info is a scalability concern, too - systems with >> many CPUs will tend to have a lot of memory, and the growing overhead >> of the page_info array may become an issue then, too. Page clustering >> may be an option to reduce/eliminate the growth, though I didn't spend >> much thought on this or possible alternatives. > > An extra 8 bytes per page per 64 CPUs is hardly a concern I think. We're > talking an overhead of 32 bytes per megabyte per CPU. Put another way, at 512 CPUs the cpumasks would incur an overhead of <2% of total memory. It's only really beyond that threshold that I'd be concerned. The fact is it'll be a good while before 512 CPUs is concerning us, and we'll have plenty of other scalability concerns, no doubt, by that point. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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