Messages in this thread Patch in this message | | | Subject | Re: Affinity managed interrupts vs non-managed interrupts | From | Dou Liyang <> | Date | Wed, 5 Sep 2018 13:46:16 +0800 |
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Hi Thomas, Kashyap,
At 09/04/2018 06:29 PM, Kashyap Desai wrote: >>> I am using " for-4.19/block " and this particular patch "a0c9259 >>> irq/matrix: Spread interrupts on allocation" is included. >>
IMO, this patch is just used for non-managed interrupts.
>> So if all 16 have their effective affinity set to CPU0 then that's > strange
But, all these 16 are managed interrupts, and will be assigned vectors by assign_managed_vector(): { cpumask_and(vector_searchmask, vector_searchmask, affmsk); cpu = cpumask_first(vector_searchmask);
... vector = irq_matrix_alloc_managed(vector_matrix, cpu); ... }
Where we always used the *first* cpu in the vector_searchmask(0-71), not the suitable one. So I guess this situation happened.
Shall we also spread the managed interrupts on allocation?
Thanks, dou -----------------8<----------------------------------------
diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c index 9f148e3d45b4..57dc05691f44 100644 --- a/arch/x86/kernel/apic/vector.c +++ b/arch/x86/kernel/apic/vector.c @@ -314,13 +314,12 @@ assign_managed_vector(struct irq_data *irqd, const struct cpumask *dest) int vector, cpu;
cpumask_and(vector_searchmask, vector_searchmask, affmsk); - cpu = cpumask_first(vector_searchmask); - if (cpu >= nr_cpu_ids) - return -EINVAL; + /* set_affinity might call here for nothing */ if (apicd->vector && cpumask_test_cpu(apicd->cpu, vector_searchmask)) return 0; - vector = irq_matrix_alloc_managed(vector_matrix, cpu); + + vector = irq_matrix_alloc_managed(vector_matrix, vector_searchmask, &cpu); trace_vector_alloc_managed(irqd->irq, vector, vector); if (vector < 0) return vector; diff --git a/include/linux/irq.h b/include/linux/irq.h index 201de12a9957..36fdeff5043a 100644 --- a/include/linux/irq.h +++ b/include/linux/irq.h @@ -1151,7 +1151,8 @@ void irq_matrix_offline(struct irq_matrix *m); void irq_matrix_assign_system(struct irq_matrix *m, unsigned int bit, bool replace); int irq_matrix_reserve_managed(struct irq_matrix *m, const struct cpumask *msk); void irq_matrix_remove_managed(struct irq_matrix *m, const struct cpumask *msk); -int irq_matrix_alloc_managed(struct irq_matrix *m, unsigned int cpu); +int irq_matrix_alloc_managed(struct irq_matrix *m, const struct cpumask *msk, + unsigned int *mapped_cpu); void irq_matrix_reserve(struct irq_matrix *m); void irq_matrix_remove_reserved(struct irq_matrix *m); int irq_matrix_alloc(struct irq_matrix *m, const struct cpumask *msk, diff --git a/kernel/irq/matrix.c b/kernel/irq/matrix.c index 5092494bf261..d9e4e0a385fa 100644 --- a/kernel/irq/matrix.c +++ b/kernel/irq/matrix.c @@ -239,21 +239,40 @@ void irq_matrix_remove_managed(struct irq_matrix *m, const struct cpumask *msk) * @m: Matrix pointer * @cpu: On which CPU the interrupt should be allocated */ -int irq_matrix_alloc_managed(struct irq_matrix *m, unsigned int cpu) +int irq_matrix_alloc_managed(struct irq_matrix *m, const struct cpumask *msk, + unsigned int *mapped_cpu) { - struct cpumap *cm = per_cpu_ptr(m->maps, cpu); - unsigned int bit, end = m->alloc_end; - - /* Get managed bit which are not allocated */ - bitmap_andnot(m->scratch_map, cm->managed_map, cm->alloc_map, end); - bit = find_first_bit(m->scratch_map, end); - if (bit >= end) - return -ENOSPC; - set_bit(bit, cm->alloc_map); - cm->allocated++; - m->total_allocated++; - trace_irq_matrix_alloc_managed(bit, cpu, m, cm); - return bit; + unsigned int cpu, best_cpu, maxavl = 0; + unsigned int bit, end; + struct cpumap *cm; + + best_cpu = UINT_MAX; + for_each_cpu(cpu, msk) { + cm = per_cpu_ptr(m->maps, cpu); + + if (!cm->online || cm->available <= maxavl) + continue; + + best_cpu = cpu; + maxavl = cm->available; + } + + if (maxavl) { + cm = per_cpu_ptr(m->maps, best_cpu); + end = m->alloc_end; + /* Get managed bit which are not allocated */ + bitmap_andnot(m->scratch_map, cm->managed_map, cm->alloc_map, end); + bit = find_first_bit(m->scratch_map, end); + if (bit >= end) + return -ENOSPC; + set_bit(bit, cm->alloc_map); + cm->allocated++; + m->total_allocated++; + *mapped_cpu = best_cpu; + trace_irq_matrix_alloc_managed(bit, cpu, m, cm); + return bit; + } + return -ENOSPC; }
/**
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