x86/irq: optimize nr_irqs

Impact: make nr_irqs depend more on cards used in a system

depend on nr_irq_gsi more, and have a ratio for MSI.

v2: make nr_irqs less than NR_VECTORS * nr_cpu_ids
    aka if only one cpu, we only can support nr_irqs = NR_VECTORS

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 11 insertions, 5 deletions

diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
index 9578d33f20a0..43f95d7b13af 100644
--- a/arch/x86/kernel/io_apic.c
+++ b/arch/x86/kernel/io_apic.c
@@ -3479,9 +3479,9 @@ int arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
         sub_handle = 0;
         list_for_each_entry(msidesc, &dev->msi_list, list) {
                 irq = create_irq_nr(irq_want);
-                irq_want++;
                 if (irq == 0)
                         return -1;
+                irq_want = irq + 1;
 #ifdef CONFIG_INTR_REMAP
                 if (!intr_remapping_enabled)
                         goto no_ir;
@@ -3825,11 +3825,17 @@ int __init arch_probe_nr_irqs(void)
 {
         int nr;
 
-        nr = ((8 * nr_cpu_ids) > (32 * nr_ioapics) ?
-                (NR_VECTORS + (8 * nr_cpu_ids)) :
-                (NR_VECTORS + (32 * nr_ioapics)));
+        if (nr_irqs > (NR_VECTORS * nr_cpu_ids))
+                nr_irqs = NR_VECTORS * nr_cpu_ids;
 
-        if (nr < nr_irqs && nr > nr_irqs_gsi)
+        nr = nr_irqs_gsi + 8 * nr_cpu_ids;
+#if defined(CONFIG_PCI_MSI) || defined(CONFIG_HT_IRQ)
+        /*
+         * for MSI and HT dyn irq
+         */
+        nr += nr_irqs_gsi * 16;
+#endif
+        if (nr < nr_irqs)
                 nr_irqs = nr;
 
         return 0;