Re: [PATCH] percpu data: only iterate over possible CPUs

[Nick Piggin]

Eric Dumazet wrote:
> Rik van Riel a écrit :
>
> > On Sun, 5 Feb 2006, Linux Kernel Mailing List wrote:
> >
> > > [PATCH] percpu data: only iterate over possible CPUs
> >
> >
> > This sched.c bit breaks Xen, and probably also other architectures
> > that have CPU hotplug.  I suspect the reason is that during early 
> > bootup only the boot CPU is online, so nothing initialises the
> > runqueues for CPUs that are brought up afterwards.
> >
> > I suspect we can get rid of this problem quite easily by moving
> > runqueue initialisation to init_idle()...
>
>
> Please fix Xen to match include/linux/cpumask.h documentation that says :
>
> /*
>  * The following particular system cpumasks and operations manage
>  * possible, present and online cpus.  Each of them is a fixed size
>  * bitmap of size NR_CPUS.
>  *
>  *  #ifdef CONFIG_HOTPLUG_CPU
>  *     cpu_possible_map - all NR_CPUS bits set

Note that this shouldn't have to be all NR_CPUs if the platform
can determine all possible hotpluggable CPUs.

--
SUSE Labs, Novell Inc.
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