x86: Convert cpu_core_map to be a per cpu variable

This is from an earlier message from 'Christoph Lameter':

    cpu_core_map is currently an array defined using NR_CPUS. This means that
    we overallocate since we will rarely really use maximum configured cpu.

    If we put the cpu_core_map into the per cpu area then it will be allocated
    for each processor as it comes online.

    This means that the core map cannot be accessed until the per cpu area
    has been allocated. Xen does a weird thing here looping over all processors
    and zeroing the masks that are not yet allocated and that will be zeroed
    when they are allocated. I commented the code out.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/include/asm-x86/smp_64.h b/include/asm-x86/smp_64.h
index 3f303d2365ed..65f844864415 100644
--- a/include/asm-x86/smp_64.h
+++ b/include/asm-x86/smp_64.h
@@ -39,7 +39,12 @@ extern int smp_num_siblings;
 extern void smp_send_reschedule(int cpu);
 
 extern cpumask_t cpu_sibling_map[NR_CPUS];
-extern cpumask_t cpu_core_map[NR_CPUS];
+/*
+ * cpu_core_map lives in a per cpu area
+ *
+ * extern cpumask_t cpu_core_map[NR_CPUS];
+ */
+DECLARE_PER_CPU(cpumask_t, cpu_core_map);
 extern u8 cpu_llc_id[NR_CPUS];
 
 #define SMP_TRAMPOLINE_BASE 0x6000