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>
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 557b8e2..539d425 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -148,7 +148,12 @@
for (cpu = 0; cpu < NR_CPUS; cpu++) {
cpus_clear(cpu_sibling_map[cpu]);
- cpus_clear(cpu_core_map[cpu]);
+ /*
+ * cpu_core_map lives in a per cpu area that is cleared
+ * when the per cpu array is allocated.
+ *
+ * cpus_clear(per_cpu(cpu_core_map, cpu));
+ */
}
xen_setup_vcpu_info_placement();
@@ -160,7 +165,12 @@
for (cpu = 0; cpu < NR_CPUS; cpu++) {
cpus_clear(cpu_sibling_map[cpu]);
- cpus_clear(cpu_core_map[cpu]);
+ /*
+ * cpu_core_ map will be zeroed when the per
+ * cpu area is allocated.
+ *
+ * cpus_clear(per_cpu(cpu_core_map, cpu));
+ */
}
smp_store_cpu_info(0);