From 1b61b910e99059abdd54c93aa70e84e076e33d16 Mon Sep 17 00:00:00 2001 From: Zhang Yanmin Date: Fri, 23 Jun 2006 02:04:22 -0700 Subject: [PATCH] x86: kernel irq balance doesn't work On i386, kernel irq balance doesn't work. 1) In function do_irq_balance, after kernel finds the min_loaded cpu but before calling set_pending_irq to really pin the selected_irq to the target cpu, kernel does a cpus_and with irq_affinity[selected_irq]. Later on, when the irq is acked, kernel would calls move_native_irq=>desc->handler->set_affinity to change the irq affinity. However, every function pointed by hw_interrupt_type->set_affinity(unsigned int irq, cpumask_t cpumask) always changes irq_affinity[irq] to cpumask. Next time when recalling do_irq_balance, it has to do cpu_ands again with irq_affinity[selected_irq], but irq_affinity[selected_irq] already becomes one cpu selected by the first irq balance. 2) Function balance_irq in file arch/i386/kernel/io_apic.c has the same issue. [akpm@osdl.org: cleanups] Signed-off-by: Zhang Yanmin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/irq.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/linux/irq.h') diff --git a/include/linux/irq.h b/include/linux/irq.h index 42c9cd56286..e8a07e75e4f 100644 --- a/include/linux/irq.h +++ b/include/linux/irq.h @@ -164,6 +164,14 @@ static inline void set_irq_info(int irq, cpumask_t mask) #endif // CONFIG_SMP +#ifdef CONFIG_IRQBALANCE +extern void set_balance_irq_affinity(unsigned int irq, cpumask_t mask); +#else +static inline void set_balance_irq_affinity(unsigned int irq, cpumask_t mask) +{ +} +#endif + extern int no_irq_affinity; extern int noirqdebug_setup(char *str); -- cgit v1.2.3