On Sat, Jun 24, 2017 at 03:02:30AM -0700, tip-bot for Daniel Lezcano wrote:
> + /*
> + * Look in the list of interrupts' statistics, the earliest
> + * next event.
> + */
> + idr_for_each_entry(&irqt_stats, s, i) {
> +
> + irqs = this_cpu_ptr(s);
> +
> + if (!irqs->valid)
> + continue;
> +
> + if (irqs->next_evt <= now) {
> + irq = i;
> + next_evt = now;
> +
> + /*
> + * This interrupt mustn't use in the future
> + * until new events occur and update the
> + * statistics.
> + */
> + irqs->valid = 0;
> + break;
> + }
> +
> + if (irqs->next_evt < next_evt) {
> + irq = i;
> + next_evt = irqs->next_evt;
> + }
> + }
That is a fairly expensive thing to do.. sure the 'continue' avoids the
very worst of it, but its still painful.
How about something like so on top? (compile tested only)
---
kernel/irq/internals.h | 4 +++-
kernel/irq/irqdesc.c | 2 ++
kernel/irq/timings.c | 35 ++++++++++++++++++++++-------------
3 files changed, 27 insertions(+), 14 deletions(-)
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index dbfba9933ed2..b96511ca7cd3 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -275,6 +275,7 @@ struct irq_timings {
DECLARE_PER_CPU(struct irq_timings, irq_timings);
+extern void irq_timings_init(void);
extern void irq_timings_free(int irq);
extern int irq_timings_alloc(int irq);
@@ -357,9 +358,10 @@ static __always_inline void record_irq_time(struct irq_desc *desc)
}
}
#else
+static inline void irq_timings_init(void) {}
static inline void irq_remove_timings(struct irq_desc *desc) {}
static inline void irq_setup_timings(struct irq_desc *desc,
- struct irqaction *act) {};
+ struct irqaction *act) {}
static inline void record_irq_time(struct irq_desc *desc) {}
#endif /* CONFIG_IRQ_TIMINGS */
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 73be2b3909bd..17e95592f291 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -493,6 +493,7 @@ int __init early_irq_init(void)
struct irq_desc *desc;
init_irq_default_affinity();
+ irq_timings_init();
/* Let arch update nr_irqs and return the nr of preallocated irqs */
initcnt = arch_probe_nr_irqs();
@@ -532,6 +533,7 @@ int __init early_irq_init(void)
struct irq_desc *desc;
init_irq_default_affinity();
+ irq_timings_init();
printk(KERN_INFO "NR_IRQS: %d\n", NR_IRQS);
diff --git a/kernel/irq/timings.c b/kernel/irq/timings.c
index c8c1d073fbf1..6bddfbb8d419 100644
--- a/kernel/irq/timings.c
+++ b/kernel/irq/timings.c
@@ -24,15 +24,17 @@
DEFINE_STATIC_KEY_FALSE(irq_timing_enabled);
DEFINE_PER_CPU(struct irq_timings, irq_timings);
+static DEFINE_PER_CPU(struct list_head, irqt_list);
struct irqt_stat {
- u64 next_evt;
- u64 last_ts;
- u64 variance;
- u32 avg;
- u32 nr_samples;
- int anomalies;
- int valid;
+ u64 next_evt;
+ u64 last_ts;
+ u64 variance;
+ u32 avg;
+ u32 nr_samples;
+ int anomalies;
+ int valid;
+ struct list_head list;
};
static DEFINE_IDR(irqt_stats);
@@ -197,6 +199,7 @@ static void irqs_update(struct irqt_stat *irqs, u64 ts)
* the next event on it.
*/
irqs->valid = 1;
+ list_add(&irqs->list, this_cpu_ptr(&irqt_list));
/*
* Online average algorithm:
@@ -254,8 +257,8 @@ static void irqs_update(struct irqt_stat *irqs, u64 ts)
u64 irq_timings_next_event(u64 now)
{
struct irq_timings *irqts = this_cpu_ptr(&irq_timings);
- struct irqt_stat *irqs;
struct irqt_stat __percpu *s;
+ struct irqt_stat *irqs, *tmp;
u64 ts, next_evt = U64_MAX;
int i, irq = 0;
@@ -297,11 +300,8 @@ u64 irq_timings_next_event(u64 now)
* Look in the list of interrupts' statistics, the earliest
* next event.
*/
- idr_for_each_entry(&irqt_stats, s, i) {
-
- irqs = this_cpu_ptr(s);
-
- if (!irqs->valid)
+ list_for_each_entry_safe(irqs, tmp, this_cpu_ptr(&irqt_list), list) {
+ if (WARN_ON_ONCE(!irqs->valid))
continue;
if (irqs->next_evt <= now) {
@@ -314,6 +314,7 @@ u64 irq_timings_next_event(u64 now)
* statistics.
*/
irqs->valid = 0;
+ list_del(&irqs->list);
break;
}
@@ -367,3 +368,11 @@ int irq_timings_alloc(int irq)
return 0;
}
+
+void __init irq_timings_init(void)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu)
+ INIT_LIST_HEAD(&per_cpu(irqt_list, cpu));
+}
--
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