| To: | Jan Beulich <jbeulich@xxxxxxxxxx>, Tim Deegan <Tim.Deegan@xxxxxxxxxx> |
|---|---|
| Subject: | Re: [Xen-devel] RFC: large system support - 128 CPUs |
| From: | Keir Fraser <keir.fraser@xxxxxxxxxxxxx> |
| Date: | 2008年8月13日 09:47:52 +0100 |
| Cc: | xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Bill Burns <bburns@xxxxxxxxxx> |
| Delivery-date: | 2008年8月13日 01:48:20 -0700 |
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| Thread-topic: | [Xen-devel] RFC: large system support - 128 CPUs |
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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. The concern over growing page_info array with growing memory is fallacious -- the overhead is a constant fraction of total memory, if #CPUs is held constant. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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