genirq: Speedup show_interrupts()
Since commit 425a5072dc
("genirq: Free irq_desc with rcu"),
show_interrupts() can be switched to rcu locking, which removes possible
contention on sparse_irq_lock.
The per_cpu count scan and print can be done without holding desc spinlock.
And there is no need to call kstat_irqs_cpu() and abuse irq_to_desc() while
holding rcu read lock, since desc and desc->kstat_irqs wont disappear or
change.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Link: https://lkml.kernel.org/r/20180620150332.163320-1-edumazet@google.com
This commit is contained in:
parent
0a13ec0bbc
commit
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@ -475,22 +475,24 @@ int show_interrupts(struct seq_file *p, void *v)
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seq_putc(p, '\n');
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}
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irq_lock_sparse();
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rcu_read_lock();
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desc = irq_to_desc(i);
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if (!desc)
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goto outsparse;
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raw_spin_lock_irqsave(&desc->lock, flags);
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for_each_online_cpu(j)
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any_count |= kstat_irqs_cpu(i, j);
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action = desc->action;
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if ((!action || irq_desc_is_chained(desc)) && !any_count)
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goto out;
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if (desc->kstat_irqs)
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for_each_online_cpu(j)
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any_count |= *per_cpu_ptr(desc->kstat_irqs, j);
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if ((!desc->action || irq_desc_is_chained(desc)) && !any_count)
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goto outsparse;
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seq_printf(p, "%*d: ", prec, i);
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for_each_online_cpu(j)
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seq_printf(p, "%10u ", kstat_irqs_cpu(i, j));
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seq_printf(p, "%10u ", desc->kstat_irqs ?
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*per_cpu_ptr(desc->kstat_irqs, j) : 0);
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raw_spin_lock_irqsave(&desc->lock, flags);
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if (desc->irq_data.chip) {
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if (desc->irq_data.chip->irq_print_chip)
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desc->irq_data.chip->irq_print_chip(&desc->irq_data, p);
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@ -511,6 +513,7 @@ int show_interrupts(struct seq_file *p, void *v)
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if (desc->name)
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seq_printf(p, "-%-8s", desc->name);
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action = desc->action;
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if (action) {
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seq_printf(p, " %s", action->name);
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while ((action = action->next) != NULL)
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@ -518,10 +521,9 @@ int show_interrupts(struct seq_file *p, void *v)
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}
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seq_putc(p, '\n');
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out:
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raw_spin_unlock_irqrestore(&desc->lock, flags);
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outsparse:
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irq_unlock_sparse();
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rcu_read_unlock();
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return 0;
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}
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#endif
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