1 files changed, 91 insertions, 20 deletions

diff --git a/arch/x86_64/kernel/smpboot.c b/arch/x86_64/kernel/smpboot.c
index c4e59bbdc187..683c33f7b967 100644
--- a/arch/x86_64/kernel/smpboot.c
+++ b/arch/x86_64/kernel/smpboot.c
@@ -64,6 +64,7 @@
 int smp_num_siblings = 1;
 /* Package ID of each logical CPU */
 u8 phys_proc_id[NR_CPUS] __read_mostly = { [0 ... NR_CPUS-1] = BAD_APICID };
+/* core ID of each logical CPU */
 u8 cpu_core_id[NR_CPUS] __read_mostly = { [0 ... NR_CPUS-1] = BAD_APICID };
 
 /* Bitmask of currently online CPUs */
@@ -87,7 +88,10 @@ struct cpuinfo_x86 cpu_data[NR_CPUS] __cacheline_aligned;
 /* Set when the idlers are all forked */
 int smp_threads_ready;
 
+/* representing HT siblings of each logical CPU */
 cpumask_t cpu_sibling_map[NR_CPUS] __read_mostly;
+
+/* representing HT and core siblings of each logical CPU */
 cpumask_t cpu_core_map[NR_CPUS] __read_mostly;
 EXPORT_SYMBOL(cpu_core_map);
 
@@ -434,30 +438,59 @@ void __cpuinit smp_callin(void)
         cpu_set(cpuid, cpu_callin_map);
 }
 
+/* representing cpus for which sibling maps can be computed */
+static cpumask_t cpu_sibling_setup_map;
+
 static inline void set_cpu_sibling_map(int cpu)
 {
         int i;
+        struct cpuinfo_x86 *c = cpu_data;
+
+        cpu_set(cpu, cpu_sibling_setup_map);
 
         if (smp_num_siblings > 1) {
-                for_each_cpu(i) {
-                        if (cpu_core_id[cpu] == cpu_core_id[i]) {
+                for_each_cpu_mask(i, cpu_sibling_setup_map) {
+                        if (phys_proc_id[cpu] == phys_proc_id[i] &&
+                            cpu_core_id[cpu] == cpu_core_id[i]) {
                                 cpu_set(i, cpu_sibling_map[cpu]);
                                 cpu_set(cpu, cpu_sibling_map[i]);
+                                cpu_set(i, cpu_core_map[cpu]);
+                                cpu_set(cpu, cpu_core_map[i]);
                         }
                 }
         } else {
                 cpu_set(cpu, cpu_sibling_map[cpu]);
         }
 
-        if (current_cpu_data.x86_num_cores > 1) {
-                for_each_cpu(i) {
-                        if (phys_proc_id[cpu] == phys_proc_id[i]) {
-                                cpu_set(i, cpu_core_map[cpu]);
-                                cpu_set(cpu, cpu_core_map[i]);
-                        }
-                }
-        } else {
+        if (current_cpu_data.x86_max_cores == 1) {
                 cpu_core_map[cpu] = cpu_sibling_map[cpu];
+                c[cpu].booted_cores = 1;
+                return;
+        }
+
+        for_each_cpu_mask(i, cpu_sibling_setup_map) {
+                if (phys_proc_id[cpu] == phys_proc_id[i]) {
+                        cpu_set(i, cpu_core_map[cpu]);
+                        cpu_set(cpu, cpu_core_map[i]);
+                        /*
+                         *  Does this new cpu bringup a new core?
+                         */
+                        if (cpus_weight(cpu_sibling_map[cpu]) == 1) {
+                                /*
+                                 * for each core in package, increment
+                                 * the booted_cores for this new cpu
+                                 */
+                                if (first_cpu(cpu_sibling_map[i]) == i)
+                                        c[cpu].booted_cores++;
+                                /*
+                                 * increment the core count for all
+                                 * the other cpus in this package
+                                 */
+                                if (i != cpu)
+                                        c[i].booted_cores++;
+                        } else if (i != cpu && !c[cpu].booted_cores)
+                                c[cpu].booted_cores = c[i].booted_cores;
+                }
         }
 }
 
@@ -879,6 +912,9 @@ static __init void disable_smp(void)
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
+
+int additional_cpus __initdata = -1;
+
 /*
  * cpu_possible_map should be static, it cannot change as cpu's
  * are onlined, or offlined. The reason is per-cpu data-structures
@@ -887,14 +923,38 @@ static __init void disable_smp(void)
  * cpu_present_map on the other hand can change dynamically.
  * In case when cpu_hotplug is not compiled, then we resort to current
  * behaviour, which is cpu_possible == cpu_present.
- * If cpu-hotplug is supported, then we need to preallocate for all
- * those NR_CPUS, hence cpu_possible_map represents entire NR_CPUS range.
  * - Ashok Raj
+ *
+ * Three ways to find out the number of additional hotplug CPUs:
+ * - If the BIOS specified disabled CPUs in ACPI/mptables use that.
+ * - otherwise use half of the available CPUs or 2, whatever is more.
+ * - The user can overwrite it with additional_cpus=NUM
+ * We do this because additional CPUs waste a lot of memory.
+ * -AK
  */
 __init void prefill_possible_map(void)
 {
         int i;
-        for (i = 0; i < NR_CPUS; i++)
+        int possible;
+
+        if (additional_cpus == -1) {
+                if (disabled_cpus > 0) {
+                        additional_cpus = disabled_cpus;
+                } else {
+                        additional_cpus = num_processors / 2;
+                        if (additional_cpus == 0)
+                                additional_cpus = 2;
+                }
+        }
+        possible = num_processors + additional_cpus;
+        if (possible > NR_CPUS) 
+                possible = NR_CPUS;
+
+        printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",
+                possible,
+                max_t(int, possible - num_processors, 0));
+
+        for (i = 0; i < possible; i++)
                 cpu_set(i, cpu_possible_map);
 }
 #endif
@@ -965,6 +1025,7 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
         nmi_watchdog_default();
         current_cpu_data = boot_cpu_data;
         current_thread_info()->cpu = 0;  /* needed? */
+        set_cpu_sibling_map(0);
 
         if (smp_sanity_check(max_cpus) < 0) {
                 printk(KERN_INFO "SMP disabled\n");
@@ -1008,8 +1069,6 @@ void __init smp_prepare_boot_cpu(void)
         int me = smp_processor_id();
         cpu_set(me, cpu_online_map);
         cpu_set(me, cpu_callout_map);
-        cpu_set(0, cpu_sibling_map[0]);
-        cpu_set(0, cpu_core_map[0]);
         per_cpu(cpu_state, me) = CPU_ONLINE;
 }
 
@@ -1062,9 +1121,6 @@ int __cpuinit __cpu_up(unsigned int cpu)
  */
 void __init smp_cpus_done(unsigned int max_cpus)
 {
-#ifndef CONFIG_HOTPLUG_CPU
-        zap_low_mappings();
-#endif
         smp_cleanup_boot();
 
 #ifdef CONFIG_X86_IO_APIC
@@ -1081,15 +1137,24 @@ void __init smp_cpus_done(unsigned int max_cpus)
 static void remove_siblinginfo(int cpu)
 {
         int sibling;
+        struct cpuinfo_x86 *c = cpu_data;
 
+        for_each_cpu_mask(sibling, cpu_core_map[cpu]) {
+                cpu_clear(cpu, cpu_core_map[sibling]);
+                /*
+                 * last thread sibling in this cpu core going down
+                 */
+                if (cpus_weight(cpu_sibling_map[cpu]) == 1)
+                        c[sibling].booted_cores--;
+        }
+                        
         for_each_cpu_mask(sibling, cpu_sibling_map[cpu])
                 cpu_clear(cpu, cpu_sibling_map[sibling]);
-        for_each_cpu_mask(sibling, cpu_core_map[cpu])
-                cpu_clear(cpu, cpu_core_map[sibling]);
         cpus_clear(cpu_sibling_map[cpu]);
         cpus_clear(cpu_core_map[cpu]);
         phys_proc_id[cpu] = BAD_APICID;
         cpu_core_id[cpu] = BAD_APICID;
+        cpu_clear(cpu, cpu_sibling_setup_map);
 }
 
 void remove_cpu_from_maps(void)
@@ -1153,6 +1218,12 @@ void __cpu_die(unsigned int cpu)
         printk(KERN_ERR "CPU %u didn't die...\n", cpu);
 }
 
+static __init int setup_additional_cpus(char *s)
+{
+        return get_option(&s, &additional_cpus);
+}
+__setup("additional_cpus=", setup_additional_cpus);
+
 #else /* ... !CONFIG_HOTPLUG_CPU */
 
 int __cpu_disable(void)