x86/apic/x2apic: Use multiple cluster members for the irq destination only with the...

[linux-2.6-block.git] / arch / x86 / kernel / apic / x2apic_cluster.c

diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c
index bde78d0098a41d4bec84b45dde6a37f848d77404..c88baa4ff0e5650061dbed84fca55b89d4c1b55e 100644 (file)
--- a/arch/x86/kernel/apic/x2apic_cluster.c
+++ b/arch/x86/kernel/apic/x2apic_cluster.c
@@ -209,13 +209,30 @@ static int x2apic_cluster_probe(void)
                return 0;
 }
 
+static const struct cpumask *x2apic_cluster_target_cpus(void)
+{
+       return cpu_all_mask;
+}
+
 /*
  * Each x2apic cluster is an allocation domain.
  */
 static void cluster_vector_allocation_domain(int cpu, struct cpumask *retmask,
                                             const struct cpumask *mask)
 {
-       cpumask_and(retmask, mask, per_cpu(cpus_in_cluster, cpu));
+       /*
+        * To minimize vector pressure, default case of boot, device bringup
+        * etc will use a single cpu for the interrupt destination.
+        *
+        * On explicit migration requests coming from irqbalance etc,
+        * interrupts will be routed to the x2apic cluster (cluster-id
+        * derived from the first cpu in the mask) members specified
+        * in the mask.
+        */
+       if (mask == x2apic_cluster_target_cpus())
+               cpumask_copy(retmask, cpumask_of(cpu));
+       else
+               cpumask_and(retmask, mask, per_cpu(cpus_in_cluster, cpu));
 }
 
 static struct apic apic_x2apic_cluster = {
@@ -229,7 +246,7 @@ static struct apic apic_x2apic_cluster = {
        .irq_delivery_mode              = dest_LowestPrio,
        .irq_dest_mode                  = 1, /* logical */
 
-       .target_cpus                    = online_target_cpus,
+       .target_cpus                    = x2apic_cluster_target_cpus,
        .disable_esr                    = 0,
        .dest_logical                   = APIC_DEST_LOGICAL,
        .check_apicid_used              = NULL,