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authorAndrew Morton <akpm@osdl.org>2006-02-10 01:51:08 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-02-10 08:13:12 -0800
commit7a8ef1cb774e5438d292365626f9b96616283706 (patch)
tree82d085204e8728d28a5267fb39aa2e26ea8824c9
parent705672935f8a9e661264e34cd8c409e8cddcc7db (diff)
downloadlinux-2.6.34-ux500-7a8ef1cb774e5438d292365626f9b96616283706.tar.gz
[PATCH] x86: don't initialise cpu_possible_map to all ones
Initialising cpu_possible_map to all-ones with CONFIG_HOTPLUG_CPU means that a) All for_each_cpu() loops will iterate across all NR_CPUS CPUs, rather than over possible ones. That can be quite expensive. b) Soon we'll be allocating per-cpu areas only for possible CPUs. So with CPU_MASK_ALL, we'll be wasting memory. I also switched voyager over to not use CPU_MASK_ALL in the non-CPU-hotplug case. Should be OK.. I note that parisc is also using CPU_MASK_ALL. Suggest that it stop doing that. Cc: James Bottomley <James.Bottomley@steeleye.com> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Paul Jackson <pj@sgi.com> Cc: Ashok Raj <ashok.raj@intel.com> Cc: Zwane Mwaikambo <zwane@linuxpower.ca> Cc: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--arch/i386/kernel/smpboot.c4
-rw-r--r--arch/i386/mach-voyager/voyager_smp.c2
-rw-r--r--include/linux/cpumask.h2
3 files changed, 2 insertions, 6 deletions
diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
index 255adb49826..fb00ab7b761 100644
--- a/arch/i386/kernel/smpboot.c
+++ b/arch/i386/kernel/smpboot.c
@@ -87,11 +87,7 @@ EXPORT_SYMBOL(cpu_online_map);
cpumask_t cpu_callin_map;
cpumask_t cpu_callout_map;
EXPORT_SYMBOL(cpu_callout_map);
-#ifdef CONFIG_HOTPLUG_CPU
-cpumask_t cpu_possible_map = CPU_MASK_ALL;
-#else
cpumask_t cpu_possible_map;
-#endif
EXPORT_SYMBOL(cpu_possible_map);
static cpumask_t smp_commenced_mask;
diff --git a/arch/i386/mach-voyager/voyager_smp.c b/arch/i386/mach-voyager/voyager_smp.c
index 72a1b9cae2e..6e4c3baef6c 100644
--- a/arch/i386/mach-voyager/voyager_smp.c
+++ b/arch/i386/mach-voyager/voyager_smp.c
@@ -240,7 +240,7 @@ static cpumask_t smp_commenced_mask = CPU_MASK_NONE;
cpumask_t cpu_callin_map = CPU_MASK_NONE;
cpumask_t cpu_callout_map = CPU_MASK_NONE;
EXPORT_SYMBOL(cpu_callout_map);
-cpumask_t cpu_possible_map = CPU_MASK_ALL;
+cpumask_t cpu_possible_map = CPU_MASK_NONE;
EXPORT_SYMBOL(cpu_possible_map);
/* The per processor IRQ masks (these are usually kept in sync) */
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 20b446f26ec..60e56c6e03d 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -328,7 +328,7 @@ static inline void __cpus_remap(cpumask_t *dstp, const cpumask_t *srcp,
* bitmap of size NR_CPUS.
*
* #ifdef CONFIG_HOTPLUG_CPU
- * cpu_possible_map - all NR_CPUS bits set
+ * cpu_possible_map - has bit 'cpu' set iff cpu is populatable
* cpu_present_map - has bit 'cpu' set iff cpu is populated
* cpu_online_map - has bit 'cpu' set iff cpu available to scheduler
* #else