2 files changed, 27 insertions, 0 deletions

diff --git a/arch/sparc64/Kconfig b/arch/sparc64/Kconfig
index a253a39c3ff6..49b652f9b1d8 100644
--- a/arch/sparc64/Kconfig
+++ b/arch/sparc64/Kconfig
@@ -356,6 +356,15 @@ config SOLARIS_EMUL
 
 endmenu
 
+config SCHED_SMT
+        bool "SMT (Hyperthreading) scheduler support"
+        depends on SMP
+        default y
+        help
+          SMT scheduler support improves the CPU scheduler's decision making
+          when dealing with UltraSPARC cpus at a cost of slightly increased
+          overhead in some places. If unsure say N here.
+
 config CMDLINE_BOOL
         bool "Default bootloader kernel arguments"
 
diff --git a/arch/sparc64/kernel/smp.c b/arch/sparc64/kernel/smp.c
index cf56128097c8..373a701c90a5 100644
--- a/arch/sparc64/kernel/smp.c
+++ b/arch/sparc64/kernel/smp.c
@@ -47,6 +47,8 @@ static unsigned char boot_cpu_id;
 
 cpumask_t cpu_online_map __read_mostly = CPU_MASK_NONE;
 cpumask_t phys_cpu_present_map __read_mostly = CPU_MASK_NONE;
+cpumask_t cpu_sibling_map[NR_CPUS] __read_mostly =
+        { [0 ... NR_CPUS-1] = CPU_MASK_NONE };
 static cpumask_t smp_commenced_mask;
 static cpumask_t cpu_callout_map;
 
@@ -1291,6 +1293,8 @@ int setup_profiling_timer(unsigned int multiplier)
 /* Constrain the number of cpus to max_cpus.  */
 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
+        int i;
+
         if (num_possible_cpus() > max_cpus) {
                 int instance, mid;
 
@@ -1305,6 +1309,20 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
                 }
         }
 
+        for_each_cpu(i) {
+                if (tlb_type == hypervisor) {
+                        int j;
+
+                        /* XXX get this mapping from machine description */
+                        for_each_cpu(j) {
+                                if ((j >> 2) == (i >> 2))
+                                        cpu_set(j, cpu_sibling_map[i]);
+                        }
+                } else {
+                        cpu_set(i, cpu_sibling_map[i]);
+                }
+        }
+
         smp_store_cpu_info(boot_cpu_id);
 }