[PATCH] irq_balance does not make sense with HT but single physicalCPU

[Kai Bankett]

Hi @all,

this patch should disable irq_balance threat in case of only one 
installed physical cpu thats running in HyperThreading-mode (so reported 
as 2 cpus).
I think it should make no sense to run irq_blanance in that special case 
- please correct me if i´m wrong.

Thanks,

Kai

diff -u -r -N linux-2.6.0-test10/arch/i386/kernel/io_apic.c linux-2.6.0-test10-kai/arch/i386/kernel/io_apic.c
--- linux-2.6.0-test10/arch/i386/kernel/io_apic.c	2003-11-24 02:31:38.000000000 +0100
+++ linux-2.6.0-test10-kai/arch/i386/kernel/io_apic.c	2003-11-26 14:30:29.000000000 +0100
@@ -627,6 +627,16 @@
 		irqbalance_disabled = 1;
 		return 0;
 	}
+
+#ifdef CONFIG_X86_HT
+	/* On Hyper-Threading CPUs - if only one physical installed
+	   balance does not make sense */
+	if (cpu_has_ht && smp_num_siblings == 2 && num_online_cpus() == 2) {
+		irqbalance_disabled = 1;
+		return 0;
+	}
+#endif
+
 	/*
 	 * Enable physical balance only if more than 1 physical processor
 	 * is present

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