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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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