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Subject[PATCH] irq_balance does not make sense with HT but single physical CPU
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[unhandled content-type:application/x-pkcs7-signature]
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