I often get asked if BAD interrupts are really bad. On some boxes (eg
IBM machines running a hypervisor) there are valid cases where are
presented with an interrupt that is not for us. These cases are common
enough to show up as thousands of BAD interrupts a day.
Tone them down by calling them spurious. Since they can be a significant cause
of OS jitter, we may as well log them per cpu so we know where they are
occurring.
Signed-off-by: Anton Blanchard <an...@samba.org>
---
Again, the short name matches x86 but if people are sufficiently confused by
it ("SPU"), then we can think up something else.
Index: linux-cpumask/arch/powerpc/include/asm/hardirq.h
===================================================================
--- linux-cpumask.orig/arch/powerpc/include/asm/hardirq.h 2010-01-30
23:27:24.787211611 +1100
+++ linux-cpumask/arch/powerpc/include/asm/hardirq.h 2010-01-30
23:27:32.277210667 +1100
@@ -9,6 +9,7 @@ typedef struct {
unsigned int timer_irqs;
unsigned int pmu_irqs;
unsigned int mce_exceptions;
+ unsigned int spurious_irqs;
#if defined(CONFIG_XICS) && defined(CONFIG_SMP)
unsigned long xics_ipi;
#endif
@@ -28,7 +29,4 @@ static inline void ack_bad_irq(unsigned
extern u64 arch_irq_stat_cpu(unsigned int cpu);
#define arch_irq_stat_cpu arch_irq_stat_cpu
-extern u64 arch_irq_stat(void);
-#define arch_irq_stat arch_irq_stat
-
#endif /* _ASM_POWERPC_HARDIRQ_H */
Index: linux-cpumask/arch/powerpc/kernel/irq.c
===================================================================
--- linux-cpumask.orig/arch/powerpc/kernel/irq.c 2010-01-30
23:27:24.787211611 +1100
+++ linux-cpumask/arch/powerpc/kernel/irq.c 2010-01-30 23:27:25.080961389
+1100
@@ -77,7 +77,6 @@ DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpusta
EXPORT_PER_CPU_SYMBOL(irq_stat);
int __irq_offset_value;
-static int ppc_spurious_interrupts;
#ifdef CONFIG_PPC32
EXPORT_SYMBOL(__irq_offset_value);
@@ -201,6 +200,11 @@ static int show_other_interrupts(struct
seq_printf(p, "%10u ", per_cpu(irq_stat, j).timer_irqs);
seq_printf(p, " Local timer interrupts\n");
+ seq_printf(p, "%*s: ", prec, "SPU");
+ for_each_online_cpu(j)
+ seq_printf(p, "%10u ", per_cpu(irq_stat, j).spurious_irqs);
+ seq_printf(p, " Spurious interrupts\n");
+
seq_printf(p, "%*s: ", prec, "CNT");
for_each_online_cpu(j)
seq_printf(p, "%10u ", per_cpu(irq_stat, j).pmu_irqs);
@@ -211,8 +215,6 @@ static int show_other_interrupts(struct
seq_printf(p, "%10u ", per_cpu(irq_stat, j).mce_exceptions);
seq_printf(p, " Machine check exceptions\n");
- seq_printf(p, "%*s: %10u\n", prec, "BAD", ppc_spurious_interrupts);
-
return 0;
}
@@ -282,13 +284,7 @@ u64 arch_irq_stat_cpu(unsigned int cpu)
sum += per_cpu(irq_stat, cpu).pmu_irqs;
sum += per_cpu(irq_stat, cpu).mce_exceptions;
-
- return sum;
-}
-
-u64 arch_irq_stat(void)
-{
- u64 sum = ppc_spurious_interrupts;
+ sum += per_cpu(irq_stat, cpu).spurious_irqs;
return sum;
}
@@ -404,8 +400,7 @@ void do_IRQ(struct pt_regs *regs)
if (irq != NO_IRQ && irq != NO_IRQ_IGNORE)
handle_one_irq(irq);
else if (irq != NO_IRQ_IGNORE)
- /* That's not SMP safe ... but who cares ? */
- ppc_spurious_interrupts++;
+ __get_cpu_var(irq_stat).spurious_irqs++;
irq_exit();
set_irq_regs(old_regs);
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