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genirq: Avoid summation loops for /proc/interrupts

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show_interrupts() unconditionally accumulates the per CPU interrupt
statistics to determine whether an interrupt was ever raised.

This can be avoided for all interrupts which are not strictly per CPU
and not of type NMI because those interrupts provide already an
accumulated counter. The required logic is already implemented in
kstat_irqs().

Split the inner access logic out of kstat_irqs() and use it for
kstat_irqs() and show_interrupts() to avoid the accumulation loop
when possible.

Originally-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Bitao Hu <yaoma@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Liu Song <liusong@linux.alibaba.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20240411074134.30922-4-yaoma@linux.alibaba.com
This commit is contained in:
Bitao Hu 2024-04-11 15:41:32 +08:00 committed by Thomas Gleixner
parent 99cf63c566
commit 25a4a01511
3 changed files with 15 additions and 9 deletions
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2
kernel/irq/internals.h
View file

@ -98,6 +98,8 @@ extern void mask_irq(struct irq_desc *desc);
extern void unmask_irq(struct irq_desc *desc);
extern void unmask_threaded_irq(struct irq_desc *desc);
extern unsigned int kstat_irqs_desc(struct irq_desc *desc, const struct cpumask *cpumask);
#ifdef CONFIG_SPARSE_IRQ
static inline void irq_mark_irq(unsigned int irq) { }
#else

16
kernel/irq/irqdesc.c
View file

@ -976,24 +976,30 @@ static bool irq_is_nmi(struct irq_desc *desc)
return desc->istate & IRQS_NMI;
}
static unsigned int kstat_irqs(unsigned int irq)
unsigned int kstat_irqs_desc(struct irq_desc *desc, const struct cpumask *cpumask)
{
struct irq_desc *desc = irq_to_desc(irq);
unsigned int sum = 0;
int cpu;
if (!desc || !desc->kstat_irqs)
return 0;
if (!irq_settings_is_per_cpu_devid(desc) &&
!irq_settings_is_per_cpu(desc) &&
!irq_is_nmi(desc))
return data_race(desc->tot_count);
for_each_possible_cpu(cpu)
for_each_cpu(cpu, cpumask)
sum += data_race(per_cpu(desc->kstat_irqs->cnt, cpu));
return sum;
}
static unsigned int kstat_irqs(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
if (!desc || !desc->kstat_irqs)
return 0;
return kstat_irqs_desc(desc, cpu_possible_mask);
}
#ifdef CONFIG_GENERIC_IRQ_STAT_SNAPSHOT
void kstat_snapshot_irqs(void)

6
kernel/irq/proc.c
View file

@ -488,10 +488,8 @@ int show_interrupts(struct seq_file *p, void *v)
if (!desc || irq_settings_is_hidden(desc))
goto outsparse;
if (desc->kstat_irqs) {
for_each_online_cpu(j)
any_count |= data_race(per_cpu(desc->kstat_irqs->cnt, j));
}
if (desc->kstat_irqs)
any_count = kstat_irqs_desc(desc, cpu_online_mask);
if ((!desc->action || irq_desc_is_chained(desc)) && !any_count)
goto outsparse;