Messages in this thread | | | Date | Thu, 11 Aug 2005 12:11:05 +0530 | From | Bharata B Rao <> | Subject | Re: [PATCH] i386 boottime for_each_cpu broken |
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On Thu, Aug 11, 2005 at 04:54:44AM +0000, Zwane Mwaikambo wrote: > for_each_cpu walks through all processors in cpu_possible_map, which is > defined as cpu_callout_map on i386 and isn't initialised until all > processors have been booted. This breaks things which do for_each_cpu > iterations early during boot. So, define cpu_possible_map as a bitmap with > NR_CPUS bits populated. This was triggered by a patch i'm working on which > does alloc_percpu before bringing up secondary processors. >
Zwane,
I don't know the context of your work here, but a couple of observations.
Since you populate cpu_possible_map with NR_CPUS, alloc_percpu() would end up allocating for all NR_CPUS. Wouldn't you have achieved the same thing by compile time allocation ? Wouldn't this change lead to NR_CPUS allocations from alloc_percpu() for all users ?
Now since you have separated cpu_possible_map from cpu_callout_map, do we need to reflect cpu_possible_map with the value from cpu_callout_map after the cpu_callout_map is initialized fully from smp_prepare_cpus().
BTW, I am working on Kiran's dynamic percpu allocator patch and making it cpu hotplug aware. With that, alloc_percpu would initially allocate only for the possible cpus and would allocate for other cpus as and when they come up.
Regards, Bharata. - 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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