On Sun, Apr 13, 2014 at 08:24:15AM +0800, Huacai Chen wrote:
> On MIPS currently, only the soft limit of cpu count (maxcpus) has its
> effect, this patch enable the hard limit (nr_cpus) as well. Processor
> cores which greater than maxcpus and less than nr_cpus can be taken up
> via cpu hotplug. The code is borrowed from X86.
>
> Signed-off-by: Huacai Chen <chenhc@xxxxxxxxxx>
Reviewed-by: Andreas Herrmann <andreas.herrmann@xxxxxxxxxxxxxxxxxx>
W/o this patch nr_cpus had no effect and all CPUs present on a chip
(even if greater than or equal to nr_cpus) could be taken online with
CPU hotplug. W/o the patch nr_cpus took effect.
Only nitpick: I find the name of the function somehow misleading.
I think it's rather a kind of fixup (to factor in nr_cpus) after
platform smp_setup might have already "prefilled"
cpu_possible_mask. At least in case of cavium-octeon this is the case.
Thanks,
Andreas
> ---
> arch/mips/kernel/setup.c | 20 ++++++++++++++++++++
> 1 files changed, 20 insertions(+), 0 deletions(-)
>
> diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
> index a842154..2f01201 100644
> --- a/arch/mips/kernel/setup.c
> +++ b/arch/mips/kernel/setup.c
> @@ -729,6 +729,25 @@ static void __init resource_init(void)
> }
> }
>
> +#ifdef CONFIG_SMP
> +static void __init prefill_possible_map(void)
> +{
> + int i, possible = num_possible_cpus();
> +
> + if (possible > nr_cpu_ids)
> + possible = nr_cpu_ids;
> +
> + for (i = 0; i < possible; i++)
> + set_cpu_possible(i, true);
> + for (; i < NR_CPUS; i++)
> + set_cpu_possible(i, false);
> +
> + nr_cpu_ids = possible;
> +}
> +#else
> +static inline void prefill_possible_map(void) {}
> +#endif
> +
> void __init setup_arch(char **cmdline_p)
> {
> cpu_probe();
> @@ -752,6 +771,7 @@ void __init setup_arch(char **cmdline_p)
>
> resource_init();
> plat_smp_setup();
> + prefill_possible_map();
>
> cpu_cache_init();
> }
> --
> 1.7.7.3
>
>
