Messages in this thread Patch in this message | | | From | Wei Gong <> | Subject | [PATCH v3] genirq: avoid long loops in handle_edge_irq | Date | Thu, 28 Sep 2023 18:06:38 +0800 |
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When there are a large number of interrupts occurring on the tx queue(irq smp_affinity=1) of the network card, changing the CPU affinity of the tx queue (echo 2 > /proc/irq/xx/smp_affinity) will cause handle_edge_irq to loop for a long time in the do {} while() loop.
After setting the IRQ CPU affinity, the next interrupt will only be activated when it arrives. Therefore, the next interrupt will still be on CPU 0. When a new CPU affinity is activated on CPU 0, subsequent interrupts will be processed on CPU 1.
cpu 0 cpu 1 - handle_edge_irq - apic_ack_irq - irq_do_set_affinity - handle_edge_irq - do { - handle_irq_event - istate &= ~IRQS_PENDIN - IRQD_IRQ_INPROGRESS - spin_unlock() - spin_lock() - istate |= IRQS_PENDIN - handle_irq_event_percpu - mask_ack_irq() - spin_unlock() - spin_unlock
} while(IRQS_PENDIN && !irq_disable)
Therefore, when determining whether to continue looping, we add a check to see if the current CPU belongs to the affinity table of the interrupt.
Signed-off-by: Wei Gong <gongwei833x@gmail.com> --- kernel/irq/chip.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c index dc94e0bf2c94..a457490bd965 100644 --- a/kernel/irq/chip.c +++ b/kernel/irq/chip.c @@ -831,7 +831,9 @@ void handle_edge_irq(struct irq_desc *desc) handle_irq_event(desc); } while ((desc->istate & IRQS_PENDING) && - !irqd_irq_disabled(&desc->irq_data)); + !irqd_irq_disabled(&desc->irq_data) && + cpumask_test_cpu(smp_processor_id(), + irq_data_get_effective_affinity_mask(&desc->irq_data))); out_unlock: raw_spin_unlock(&desc->lock); -- 2.32.1 (Apple Git-133)
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