x86: arch_probe_nr_irqs

Impact: save RAM with large NR_CPUS, get smaller nr_irqs

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Mike Travis <travis@sgi.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
index ae80638012de..157986916cd1 100644
--- a/arch/x86/kernel/io_apic.c
+++ b/arch/x86/kernel/io_apic.c
@@ -3850,6 +3850,22 @@ void __init probe_nr_irqs_gsi(void)
                 nr_irqs_gsi = nr;
 }
 
+#ifdef CONFIG_SPARSE_IRQ
+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 < nr_irqs && nr > nr_irqs_gsi)
+                nr_irqs = nr;
+
+        return 0;
+}
+#endif
+
 /* --------------------------------------------------------------------------
                           ACPI-based IOAPIC Configuration
    -------------------------------------------------------------------------- */