[PATCH 02/10] init: move setup of nr_cpu_ids to as early as possible v4

Mike Travis
2008-03-25T02:22:54Z

[-- Attachment #1: setup-nr_cpu_ids --]
[-- Type: text/plain, Size: 5768 bytes --]

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 linux-2.6.25-rc5-mm1

# 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.

---

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/setup64.c | 7 ++++++-
init/main.c | 15 ++++++++++++---
kernel/sched.c | 7 -------
7 files changed, 42 insertions(+), 13 deletions(-)

--- linux-2.6.25-rc5.orig/arch/ia64/kernel/acpi.c
+++ linux-2.6.25-rc5/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-2.6.25-rc5.orig/arch/ia64/kernel/setup.c
+++ linux-2.6.25-rc5/arch/ia64/kernel/setup.c
@@ -766,6 +766,13 @@ 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-2.6.25-rc5.orig/arch/powerpc/kernel/setup_64.c
+++ linux-2.6.25-rc5/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-2.6.25-rc5.orig/arch/sparc64/mm/init.c
+++ linux-2.6.25-rc5/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-2.6.25-rc5.orig/arch/x86/kernel/setup64.c
+++ linux-2.6.25-rc5/arch/x86/kernel/setup64.c
@@ -122,7 +122,7 @@ static void __init setup_per_cpu_maps(vo
*/
void __init setup_per_cpu_areas(void)
{
- int i;
+ int i, highest_cpu = 0;
unsigned long size;

#ifdef CONFIG_HOTPLUG_CPU
@@ -157,7 +157,12 @@ void __init setup_per_cpu_areas(void)

cpu_pda(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;
+ 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-2.6.25-rc5.orig/init/main.c
+++ linux-2.6.25-rc5/init/main.c
@@ -369,16 +369,20 @@ 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);
@@ -388,7 +392,12 @@ 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-2.6.25-rc5.orig/kernel/sched.c
+++ linux-2.6.25-rc5/kernel/sched.c
@@ -5995,10 +5995,6 @@ 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)
@@ -7199,7 +7195,6 @@ static void init_tg_rt_entry(struct rq *

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

#ifdef CONFIG_SMP
@@ -7255,7 +7250,6 @@ void __init sched_init(void)
#endif
init_rq_hrtick(rq);
atomic_set(&rq->nr_iowait, 0);
- highest_cpu = i;
}

set_load_weight(&init_task);
@@ -7265,7 +7259,6 @@ void __init sched_init(void)
#endif

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

--