With NO_HZ it is useful to know how often the decrementer is going off. The
patch below adds an entry for it and also adds it into the /proc/stat
summaries.
While here, I added performance monitoring and machine check exceptions.
I found it useful to keep an eye on the PMU exception rate
when using the perf tool. Since it's possible to take a completely
handled machine check on a System p box it also sounds like a good idea to
keep a machine check summary.
The event naming matches x86 to keep gratuitous differences to a minimum.
Signed-off-by: Anton Blanchard <an...@samba.org>
---
If people really don't like the x86 short names, 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
20:15:07.148462638 +1100
+++ linux-cpumask/arch/powerpc/include/asm/hardirq.h 2010-01-30
21:33:43.160961369 +1100
@@ -6,6 +6,9 @@
typedef struct {
unsigned int __softirq_pending;
+ unsigned int timer_irqs;
+ unsigned int pmu_irqs;
+ unsigned int mce_exceptions;
#if defined(CONFIG_XICS) && defined(CONFIG_SMP)
unsigned long xics_ipi;
#endif
@@ -22,4 +25,10 @@ static inline void ack_bad_irq(unsigned
printk(KERN_CRIT "unexpected IRQ trap at vector %02x\n", irq);
}
+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/time.c
===================================================================
--- linux-cpumask.orig/arch/powerpc/kernel/time.c 2010-01-30
20:15:07.138465242 +1100
+++ linux-cpumask/arch/powerpc/kernel/time.c 2010-01-30 20:15:21.077211379
+1100
@@ -575,6 +575,8 @@ void timer_interrupt(struct pt_regs * re
trace_timer_interrupt_entry(regs);
+ __get_cpu_var(irq_stat).timer_irqs++;
+
/* Ensure a positive value is written to the decrementer, or else
* some CPUs will continuue to take decrementer exceptions */
set_dec(DECREMENTER_MAX);
Index: linux-cpumask/arch/powerpc/kernel/irq.c
===================================================================
--- linux-cpumask.orig/arch/powerpc/kernel/irq.c 2010-01-30
20:15:17.287210745 +1100
+++ linux-cpumask/arch/powerpc/kernel/irq.c 2010-01-30 21:35:54.528460683
+1100
@@ -196,6 +196,21 @@ static int show_other_interrupts(struct
}
#endif /* CONFIG_PPC32 && CONFIG_TAU_INT */
+ seq_printf(p, "%*s: ", prec, "LOC");
+ for_each_online_cpu(j)
+ seq_printf(p, "%10u ", per_cpu(irq_stat, j).timer_irqs);
+ seq_printf(p, " Local timer interrupts\n");
+
+ seq_printf(p, "%*s: ", prec, "CNT");
+ for_each_online_cpu(j)
+ seq_printf(p, "%10u ", per_cpu(irq_stat, j).pmu_irqs);
+ seq_printf(p, " Performance monitoring interrupts\n");
+
+ seq_printf(p, "%*s: ", prec, "MCE");
+ for_each_online_cpu(j)
+ 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;
@@ -258,6 +273,26 @@ out:
return 0;
}
+/*
+ * /proc/stat helpers
+ */
+u64 arch_irq_stat_cpu(unsigned int cpu)
+{
+ u64 sum = per_cpu(irq_stat, cpu).timer_irqs;
+
+ 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;
+
+ return sum;
+}
+
#ifdef CONFIG_HOTPLUG_CPU
void fixup_irqs(cpumask_t map)
{
Index: linux-cpumask/arch/powerpc/kernel/traps.c
===================================================================
--- linux-cpumask.orig/arch/powerpc/kernel/traps.c 2010-01-30
20:15:07.118462038 +1100
+++ linux-cpumask/arch/powerpc/kernel/traps.c 2010-01-30 21:31:57.487211520
+1100
@@ -478,6 +478,8 @@ void machine_check_exception(struct pt_r
{
int recover = 0;
+ __get_cpu_var(irq_stat).mce_exceptions++;
+
/* See if any machine dependent calls. In theory, we would want
* to call the CPU first, and call the ppc_md. one if the CPU
* one returns a positive number. However there is existing code
@@ -960,6 +962,8 @@ void vsx_unavailable_exception(struct pt
void performance_monitor_exception(struct pt_regs *regs)
{
+ __get_cpu_var(irq_stat).pmu_irqs++;
+
perf_irq(regs);
}
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