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    Subject[PATCH 02/10] init: move setup of nr_cpu_ids to as early as possible v2
    Move the setting of nr_cpu_ids from sched_init() to setup_per_cpu_areas(),
    so that it's available as early as possible.

    Based on:
    git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
    git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86.git

    # ia64
    Cc: Tony Luck <tony.luck@intel.com>

    # powerpc
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Anton Blanchard <anton@samba.org>

    # sparc
    Cc: David S. Miller <davem@davemloft.net>
    Cc: William L. Irwin <wli@holomorphy.com>

    # x86
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: H. Peter Anvin <hpa@zytor.com>

    Signed-off-by: Mike Travis <travis@sgi.com>
    ---

    Moved from the zero-based percpu variables patchset and redone to be
    integrated with setup_per_cpu_areas instead of being called before
    that function. This had to be done because some arch's call
    prefill_possible_map() from setup_per_cpu_areas() which may increase
    the number of possible cpus.

    v2: rebased on linux-2.6.git + linux-2.6-x86.git
    ---

    arch/ia64/kernel/acpi.c | 4 ++++
    arch/ia64/kernel/setup.c | 7 +++++++
    arch/powerpc/kernel/setup_64.c | 5 ++++-
    arch/sparc64/mm/init.c | 10 +++++++++-
    arch/x86/kernel/setup.c | 10 +++++++---
    init/main.c | 15 ++++++++++++---
    kernel/sched.c | 7 -------
    7 files changed, 43 insertions(+), 15 deletions(-)

    --- linux.trees.git.orig/arch/ia64/kernel/acpi.c
    +++ linux.trees.git/arch/ia64/kernel/acpi.c
    @@ -831,6 +831,10 @@ __init void prefill_possible_map(void)

    for (i = 0; i < possible; i++)
    cpu_set(i, cpu_possible_map);
    +
    +#ifdef CONFIG_SMP
    + nr_cpu_ids = possible;
    +#endif
    }

    int acpi_map_lsapic(acpi_handle handle, int *pcpu)
    --- linux.trees.git.orig/arch/ia64/kernel/setup.c
    +++ linux.trees.git/arch/ia64/kernel/setup.c
    @@ -765,6 +765,13 @@ setup_per_cpu_areas (void)
    /* start_kernel() requires this... */
    #ifdef CONFIG_ACPI_HOTPLUG_CPU
    prefill_possible_map();
    +#elif defined(CONFIG_SMP)
    + int cpu, highest_cpu = 0;
    +
    + for_each_possible_cpu(cpu)
    + highest_cpu = cpu;
    +
    + nr_cpu_ids = highest_cpu + 1;
    #endif
    }

    --- linux.trees.git.orig/arch/powerpc/kernel/setup_64.c
    +++ linux.trees.git/arch/powerpc/kernel/setup_64.c
    @@ -576,7 +576,7 @@ void cpu_die(void)
    #ifdef CONFIG_SMP
    void __init setup_per_cpu_areas(void)
    {
    - int i;
    + int i, highest_cpu = 0;
    unsigned long size;
    char *ptr;

    @@ -594,7 +594,10 @@ void __init setup_per_cpu_areas(void)

    paca[i].data_offset = ptr - __per_cpu_start;
    memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
    + if (i > highest_cpu)
    + highest_cpu = i;
    }
    + nr_cpu_ids = highest_cpu + 1;

    /* Now that per_cpu is setup, initialize cpu_sibling_map */
    smp_setup_cpu_sibling_map();
    --- linux.trees.git.orig/arch/sparc64/mm/init.c
    +++ linux.trees.git/arch/sparc64/mm/init.c
    @@ -1292,10 +1292,18 @@ pgd_t swapper_pg_dir[2048];
    static void sun4u_pgprot_init(void);
    static void sun4v_pgprot_init(void);

    -/* Dummy function */
    +#ifdef CONFIG_SMP
    +/* set nr_cpu_ids */
    void __init setup_per_cpu_areas(void)
    {
    + int cpu, highest_cpu = 0;
    +
    + for_each_possible_cpu(cpu)
    + highest_cpu = cpu;
    +
    + nr_cpu_ids = highest_cpu + 1;
    }
    +#endif

    void __init paging_init(void)
    {
    --- linux.trees.git.orig/arch/x86/kernel/setup.c
    +++ linux.trees.git/arch/x86/kernel/setup.c
    @@ -54,7 +54,7 @@ EXPORT_SYMBOL(__per_cpu_offset);
    */
    void __init setup_per_cpu_areas(void)
    {
    - int i;
    + int i, highest_cpu = 0;
    unsigned long size;

    #ifdef CONFIG_HOTPLUG_CPU
    @@ -80,15 +80,19 @@ void __init setup_per_cpu_areas(void)
    else
    ptr = alloc_bootmem_pages_node(NODE_DATA(node), size);
    #endif
    - if (!ptr)
    - panic("Cannot allocate cpu data for CPU %d\n", i);
    +
    #ifdef CONFIG_X86_64
    cpu_pda(i)->data_offset = ptr - __per_cpu_start;
    #else
    __per_cpu_offset[i] = ptr - __per_cpu_start;
    #endif
    memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
    +
    + if (i > highest_cpu)
    + highest_cpu = i;
    }
    + nr_cpu_ids = highest_cpu + 1;
    + printk(KERN_DEBUG "NR_CPUS:%d (nr_cpu_ids:%d)\n", NR_CPUS, nr_cpu_ids);

    /* Setup percpu data maps */
    setup_per_cpu_maps();
    --- linux.trees.git.orig/init/main.c
    +++ linux.trees.git/init/main.c
    @@ -364,16 +364,20 @@ static inline void smp_prepare_cpus(unsi

    #else

    +int nr_cpu_ids __read_mostly = NR_CPUS;
    +EXPORT_SYMBOL(nr_cpu_ids);
    +
    #ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
    unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
    -
    EXPORT_SYMBOL(__per_cpu_offset);

    +/* nr_cpu_ids is set as a side effect */
    static void __init setup_per_cpu_areas(void)
    {
    - unsigned long size, i;
    - char *ptr;
    + unsigned long size;
    + int i, highest_cpu = 0;
    unsigned long nr_possible_cpus = num_possible_cpus();
    + char *ptr;

    /* Copy section for each CPU (we discard the original) */
    size = ALIGN(PERCPU_ENOUGH_ROOM, PAGE_SIZE);
    @@ -383,7 +387,12 @@ static void __init setup_per_cpu_areas(v
    __per_cpu_offset[i] = ptr - __per_cpu_start;
    memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
    ptr += size;
    + if (i > highest_cpu)
    + highest_cpu = i;
    }
    +
    + nr_cpu_ids = highest_cpu + 1;
    + printk(KERN_DEBUG "NR_CPUS:%d (nr_cpu_ids:%d)\n", NR_CPUS, nr_cpu_ids);
    }
    #endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */

    --- linux.trees.git.orig/kernel/sched.c
    +++ linux.trees.git/kernel/sched.c
    @@ -5923,10 +5923,6 @@ void __init migration_init(void)

    #ifdef CONFIG_SMP

    -/* Number of possible processor ids */
    -int nr_cpu_ids __read_mostly = NR_CPUS;
    -EXPORT_SYMBOL(nr_cpu_ids);
    -
    #ifdef CONFIG_SCHED_DEBUG

    static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level)
    @@ -7152,7 +7148,6 @@ static void init_tg_rt_entry(struct rq *

    void __init sched_init(void)
    {
    - int highest_cpu = 0;
    int i, j;

    #ifdef CONFIG_SMP
    @@ -7207,7 +7202,6 @@ void __init sched_init(void)
    #endif
    init_rq_hrtick(rq);
    atomic_set(&rq->nr_iowait, 0);
    - highest_cpu = i;
    }

    set_load_weight(&init_task);
    @@ -7217,7 +7211,6 @@ void __init sched_init(void)
    #endif

    #ifdef CONFIG_SMP
    - nr_cpu_ids = highest_cpu + 1;
    open_softirq(SCHED_SOFTIRQ, run_rebalance_domains, NULL);
    #endif

    --


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