Messages in this thread | | | Subject | RE: [PATCH] Fix hotplug cpu on x86_64 | Date | Fri, 7 Oct 2005 11:42:13 -0500 | From | "Protasevich, Natalie" <> |
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> > sure convenient. I though at the time it would be great if > > alloc_percpu() mechanism was able to dynamically re-create all the > > per_cpu's for new processors, that way cpu_possible_map woun't > > probably even be needed. Or is it too much trouble for too > little gain... > > The problem is to tell all subsystems to reinitialize the > data for possible CPUs (essentially the concept of "possible" > CPUs would need to go) It would need an reaudit of a lot of > code. Probably quite some work.
You know Andi, I was imagining something like bitmap or linked list of all per_cpu vars (dynamically updated) and just going through this list... Or something like that (maybe some registration mechanism). There are not too many of them - about two dozens, mostly all sorts of accounting.
> I think it is better to try to figure out how many hotplug > CPUs are supported, otherwise use a small default.
Exactly - such as on ES7000, it can support 32, 64, 128 etc. processors depending on what configuration the customer actually ordered :)... it should be something for that, then NR_CPUS could be either defined as boot parameter or belong to subarchs. Thanks, --Natalie
> My > current code uses disabled CPUs as a heuristic, otherwise > half of available CPUs and it can be overwritten by the user. > > -Andi > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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