[PATCH][2.5] Disable irqbalance for single cpu SMP configurations

[Zwane Mwaikambo]

This patch disables irqbalance and doesn't spawn a kernel thread for 
systems which run SMP kernels and only have one online cpu.

Index: linux-2.5.66/arch/i386/kernel/io_apic.c
===================================================================
RCS file: /build/cvsroot/linux-2.5.66/arch/i386/kernel/io_apic.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 io_apic.c
--- linux-2.5.66/arch/i386/kernel/io_apic.c	24 Mar 2003 23:40:27 -0000	1.1.1.1
+++ linux-2.5.66/arch/i386/kernel/io_apic.c	7 Apr 2003 05:19:26 -0000
@@ -603,6 +603,12 @@ static int __init balanced_irq_init(void
         c = &boot_cpu_data;
 	if (irqbalance_disabled)
 		return 0;
+	
+	 /* disable irqbalance completely if there is only one processor online */
+	if (num_online_cpus() < 2) {
+		irqbalance_disabled = 1;
+		return 0;
+	}
 	/*
 	 * Enable physical balance only if more than 1 physical processor
 	 * is present

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