Messages in this thread | | | Subject | Re: [PATCH v3 2/2] irqchip/gic-v3-its: Balance initial LPI affinity across CPUs | From | John Garry <> | Date | Wed, 18 Mar 2020 12:22:09 +0000 |
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I may have an idea about this: irq 196, cpu list 0-31, effective list 82
Just going back to comment on the code:
> +/* > + * As suggested by Thomas Gleixner in: > + * https://lore.kernel.org/r/87h80q2aoc.fsf@nanos.tec.linutronix.de > + */ > +static int its_select_cpu(struct irq_data *d, > + const struct cpumask *aff_mask) > +{ > + struct its_device *its_dev = irq_data_get_irq_chip_data(d); > + cpumask_var_t tmpmask; > + int cpu, node; > + > + if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL)) > + return -ENOMEM; > + > + node = its_dev->its->numa_node; > + > + if (!irqd_affinity_is_managed(d)) { > + /* First try the NUMA node */ > + if (node != NUMA_NO_NODE) { > + /* > + * Try the intersection of the affinity mask and the > + * node mask (and the online mask, just to be safe). > + */ > + cpumask_and(tmpmask, cpumask_of_node(node), aff_mask); > + cpumask_and(tmpmask, tmpmask, cpu_online_mask); > + > + /* If that doesn't work, try the nodemask itself */
So if tmpmsk is empty...
> + if (cpumask_empty(tmpmask)) > + cpumask_and(tmpmask, cpumask_of_node(node), cpu_online_mask);
now the tmpmask may have no intersection with the aff_mask...
> + > + cpu = cpumask_pick_least_loaded(d, tmpmask); > + if (cpu < nr_cpu_ids) > + goto out; > + > + /* If we can't cross sockets, give up */ > + if ((its_dev->its->flags & ITS_FLAGS_WORKAROUND_CAVIUM_23144)) > + goto out; > + > + /* If the above failed, expand the search */ > + }
SNIP
> +out: > + free_cpumask_var(tmpmask); > + > + pr_debug("IRQ%d -> %*pbl CPU%d\n", d->irq, cpumask_pr_args(aff_mask), cpu); > + return cpu; > +} > + > static int its_set_affinity(struct irq_data *d, const struct cpumask *mask_val, > bool force) > { > - unsigned int cpu; > - const struct cpumask *cpu_mask = cpu_online_mask; > struct its_device *its_dev = irq_data_get_irq_chip_data(d); > struct its_collection *target_col; > u32 id = its_get_event_id(d); > + int cpu; > > /* A forwarded interrupt should use irq_set_vcpu_affinity */ > if (irqd_is_forwarded_to_vcpu(d)) > return -EINVAL; > > - /* lpi cannot be routed to a redistributor that is on a foreign node */ > - if (its_dev->its->flags & ITS_FLAGS_WORKAROUND_CAVIUM_23144) { > - if (its_dev->its->numa_node >= 0) { > - cpu_mask = cpumask_of_node(its_dev->its->numa_node); > - if (!cpumask_intersects(mask_val, cpu_mask)) > - return -EINVAL; > - } > - } > - > - cpu = cpumask_any_and(mask_val, cpu_mask); > + if (!force) > + cpu = its_select_cpu(d, mask_val); > + else > + cpu = cpumask_pick_least_loaded(d, mask_val); > > - if (cpu >= nr_cpu_ids) > + if (cpu < 0 || cpu >= nr_cpu_ids) > return -EINVAL;
Annotate missing code:
if (cpu < 0 || cpu >= nr_cpu_ids) return -EINVAL;
if (cpu != its_dev->event_map.col_map[id]) { its_inc_lpi_count(d, cpu); its_dec_lpi_count(d, its_dev->event_map.col_map[id]); target_col = &its_dev->its->collections[cpu]; its_send_movi(its_dev, target_col, id); its_dev->event_map.col_map[id] = cpu; irq_data_update_effective_affinity(d, cpumask_of(cpu)); }
So cpu may not be a member of mask_val. Hence the inconsistency of the affinity list and effective affinity. We could just drop the AND of the ITS node mask in its_select_cpu().
Anyway, I don't think that this should stop us testing.
Cheers, John
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