diff options
Diffstat (limited to 'drivers/xen')
| -rw-r--r-- | drivers/xen/events/events_base.c | 76 |
1 files changed, 68 insertions, 8 deletions
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c index b352440963ee..a8030332a191 100644 --- a/drivers/xen/events/events_base.c +++ b/drivers/xen/events/events_base.c @@ -96,6 +96,7 @@ struct irq_info { struct list_head eoi_list; short refcnt; u8 spurious_cnt; + u8 is_accounted; enum xen_irq_type type; /* type */ unsigned irq; evtchn_port_t evtchn; /* event channel */ @@ -161,6 +162,9 @@ static DEFINE_PER_CPU(int [NR_VIRQS], virq_to_irq) = {[0 ... NR_VIRQS-1] = -1}; /* IRQ <-> IPI mapping */ static DEFINE_PER_CPU(int [XEN_NR_IPIS], ipi_to_irq) = {[0 ... XEN_NR_IPIS-1] = -1}; +/* Event channel distribution data */ +static atomic_t channels_on_cpu[NR_CPUS]; + static int **evtchn_to_irq; #ifdef CONFIG_X86 static unsigned long *pirq_eoi_map; @@ -257,6 +261,32 @@ static void set_info_for_irq(unsigned int irq, struct irq_info *info) irq_set_chip_data(irq, info); } +/* Per CPU channel accounting */ +static void channels_on_cpu_dec(struct irq_info *info) +{ + if (!info->is_accounted) + return; + + info->is_accounted = 0; + + if (WARN_ON_ONCE(info->cpu >= nr_cpu_ids)) + return; + + WARN_ON_ONCE(!atomic_add_unless(&channels_on_cpu[info->cpu], -1 , 0)); +} + +static void channels_on_cpu_inc(struct irq_info *info) +{ + if (WARN_ON_ONCE(info->cpu >= nr_cpu_ids)) + return; + + if (WARN_ON_ONCE(!atomic_add_unless(&channels_on_cpu[info->cpu], 1, + INT_MAX))) + return; + + info->is_accounted = 1; +} + /* Constructors for packed IRQ information. */ static int xen_irq_info_common_setup(struct irq_info *info, unsigned irq, @@ -339,6 +369,7 @@ static void xen_irq_info_cleanup(struct irq_info *info) { set_evtchn_to_irq(info->evtchn, -1); info->evtchn = 0; + channels_on_cpu_dec(info); } /* @@ -449,7 +480,9 @@ static void bind_evtchn_to_cpu(evtchn_port_t evtchn, unsigned int cpu, xen_evtchn_port_bind_to_cpu(evtchn, cpu, info->cpu); + channels_on_cpu_dec(info); info->cpu = cpu; + channels_on_cpu_inc(info); } /** @@ -622,11 +655,6 @@ static void xen_irq_init(unsigned irq) { struct irq_info *info; -#ifdef CONFIG_SMP - /* By default all event channels notify CPU#0. */ - cpumask_copy(irq_get_affinity_mask(irq), cpumask_of(0)); -#endif - info = kzalloc(sizeof(*info), GFP_KERNEL); if (info == NULL) panic("Unable to allocate metadata for IRQ%d\n", irq); @@ -1697,10 +1725,38 @@ static int xen_rebind_evtchn_to_cpu(evtchn_port_t evtchn, unsigned int tcpu) return 0; } +/* + * Find the CPU within @dest mask which has the least number of channels + * assigned. This is not precise as the per cpu counts can be modified + * concurrently. + */ +static unsigned int select_target_cpu(const struct cpumask *dest) +{ + unsigned int cpu, best_cpu = UINT_MAX, minch = UINT_MAX; + + for_each_cpu_and(cpu, dest, cpu_online_mask) { + unsigned int curch = atomic_read(&channels_on_cpu[cpu]); + + if (curch < minch) { + minch = curch; + best_cpu = cpu; + } + } + + /* + * Catch the unlikely case that dest contains no online CPUs. Can't + * recurse. + */ + if (best_cpu == UINT_MAX) + return select_target_cpu(cpu_online_mask); + + return best_cpu; +} + static int set_affinity_irq(struct irq_data *data, const struct cpumask *dest, bool force) { - unsigned tcpu = cpumask_first_and(dest, cpu_online_mask); + unsigned int tcpu = select_target_cpu(dest); int ret; ret = xen_rebind_evtchn_to_cpu(evtchn_from_irq(data->irq), tcpu); @@ -1928,8 +1984,12 @@ void xen_irq_resume(void) xen_evtchn_resume(); /* No IRQ <-> event-channel mappings. */ - list_for_each_entry(info, &xen_irq_list_head, list) - info->evtchn = 0; /* zap event-channel binding */ + list_for_each_entry(info, &xen_irq_list_head, list) { + /* Zap event-channel binding */ + info->evtchn = 0; + /* Adjust accounting */ + channels_on_cpu_dec(info); + } clear_evtchn_to_irq_all(); |