The patch titled irq: use per_cpu kstat_irqs has been added to the -mm tree. Its filename is irq-use-per_cpu-kstat_irqs.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: irq: use per_cpu kstat_irqs From: Eric Dumazet <eric.dumazet@xxxxxxxxx> Use modern per_cpu API to increment {soft|hard}irq counters, and use per_cpu allocation for (struct irq_desc)->kstats_irq instead of an array. This gives better SMP/NUMA locality and saves few instructions per irq. With small nr_cpuids values (8 for example), kstats_irq was a small array (less than L1_CACHE_BYTES), potentially source of false sharing. In the !CONFIG_SPARSE_IRQ case, remove the huge, NUMA/cache unfriendly kstat_irqs_all[NR_IRQS][NR_CPUS] array. Note : we still populate kstats_irq for all possible irqs in early_irq_init(). We probably could use on-demand allocations. (Code included in alloc_descs()). Problem is not all IRQS are used with a prior alloc_descs() call. kstat_irqs_this_cpu() is not used anymore, remove it. Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: Andi Kleen <andi@xxxxxxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/irqdesc.h | 2 - include/linux/kernel_stat.h | 19 +++++++--------- kernel/irq/irqdesc.c | 40 +++++++++++++++++++++++++--------- 3 files changed, 40 insertions(+), 21 deletions(-) diff -puN include/linux/irqdesc.h~irq-use-per_cpu-kstat_irqs include/linux/irqdesc.h --- a/include/linux/irqdesc.h~irq-use-per_cpu-kstat_irqs +++ a/include/linux/irqdesc.h @@ -57,7 +57,7 @@ struct irq_desc { #endif struct timer_rand_state *timer_rand_state; - unsigned int *kstat_irqs; + unsigned int __percpu *kstat_irqs; irq_flow_handler_t handle_irq; struct irqaction *action; /* IRQ action list */ unsigned int status; /* IRQ status */ diff -puN include/linux/kernel_stat.h~irq-use-per_cpu-kstat_irqs include/linux/kernel_stat.h --- a/include/linux/kernel_stat.h~irq-use-per_cpu-kstat_irqs +++ a/include/linux/kernel_stat.h @@ -46,16 +46,14 @@ DECLARE_PER_CPU(struct kernel_stat, ksta extern unsigned long long nr_context_switches(void); #ifndef CONFIG_GENERIC_HARDIRQS -#define kstat_irqs_this_cpu(irq) \ - (kstat_this_cpu.irqs[irq]) struct irq_desc; static inline void kstat_incr_irqs_this_cpu(unsigned int irq, struct irq_desc *desc) { - kstat_this_cpu.irqs[irq]++; - kstat_this_cpu.irqs_sum++; + __this_cpu_inc(kstat.irqs[irq]); + __this_cpu_inc(kstat.irqs_sum); } static inline unsigned int kstat_irqs_cpu(unsigned int irq, int cpu) @@ -65,17 +63,18 @@ static inline unsigned int kstat_irqs_cp #else #include <linux/irq.h> extern unsigned int kstat_irqs_cpu(unsigned int irq, int cpu); -#define kstat_irqs_this_cpu(DESC) \ - ((DESC)->kstat_irqs[smp_processor_id()]) -#define kstat_incr_irqs_this_cpu(irqno, DESC) do {\ - ((DESC)->kstat_irqs[smp_processor_id()]++);\ - kstat_this_cpu.irqs_sum++; } while (0) + +#define kstat_incr_irqs_this_cpu(irqno, DESC) \ +do { \ + __this_cpu_inc(*(DESC)->kstat_irqs); \ + __this_cpu_inc(kstat.irqs_sum); \ +} while (0) #endif static inline void kstat_incr_softirqs_this_cpu(unsigned int irq) { - kstat_this_cpu.softirqs[irq]++; + __this_cpu_inc(kstat.softirqs[irq]); } static inline unsigned int kstat_softirqs_cpu(unsigned int irq, int cpu) diff -puN kernel/irq/irqdesc.c~irq-use-per_cpu-kstat_irqs kernel/irq/irqdesc.c --- a/kernel/irq/irqdesc.c~irq-use-per_cpu-kstat_irqs +++ a/kernel/irq/irqdesc.c @@ -72,6 +72,8 @@ static inline int desc_node(struct irq_d static void desc_set_defaults(unsigned int irq, struct irq_desc *desc, int node) { + int cpu; + desc->irq_data.irq = irq; desc->irq_data.chip = &no_irq_chip; desc->irq_data.chip_data = NULL; @@ -83,7 +85,8 @@ static void desc_set_defaults(unsigned i desc->irq_count = 0; desc->irqs_unhandled = 0; desc->name = NULL; - memset(desc->kstat_irqs, 0, nr_cpu_ids * sizeof(*(desc->kstat_irqs))); + for_each_possible_cpu(cpu) + *per_cpu_ptr(desc->kstat_irqs, cpu) = 0; desc_smp_init(desc, node); } @@ -133,8 +136,7 @@ static struct irq_desc *alloc_desc(int i if (!desc) return NULL; /* allocate based on nr_cpu_ids */ - desc->kstat_irqs = kzalloc_node(nr_cpu_ids * sizeof(*desc->kstat_irqs), - gfp, node); + desc->kstat_irqs = alloc_percpu(unsigned int); if (!desc->kstat_irqs) goto err_desc; @@ -149,7 +151,7 @@ static struct irq_desc *alloc_desc(int i return desc; err_kstat: - kfree(desc->kstat_irqs); + free_percpu(desc->kstat_irqs); err_desc: kfree(desc); return NULL; @@ -166,7 +168,7 @@ static void free_desc(unsigned int irq) mutex_unlock(&sparse_irq_lock); free_masks(desc); - kfree(desc->kstat_irqs); + free_percpu(desc->kstat_irqs); kfree(desc); } @@ -234,7 +236,6 @@ struct irq_desc irq_desc[NR_IRQS] __cach } }; -static unsigned int kstat_irqs_all[NR_IRQS][NR_CPUS]; int __init early_irq_init(void) { int count, i, node = first_online_node; @@ -250,7 +251,8 @@ int __init early_irq_init(void) for (i = 0; i < count; i++) { desc[i].irq_data.irq = i; desc[i].irq_data.chip = &no_irq_chip; - desc[i].kstat_irqs = kstat_irqs_all[i]; + /* TODO : do this allocation on-demand ... */ + desc[i].kstat_irqs = alloc_percpu(unsigned int); alloc_masks(desc + i, GFP_KERNEL, node); desc_smp_init(desc + i, node); lockdep_set_class(&desc[i].lock, &irq_desc_lock_class); @@ -275,6 +277,22 @@ static void free_desc(unsigned int irq) static inline int alloc_descs(unsigned int start, unsigned int cnt, int node) { +#if defined(CONFIG_KSTAT_IRQS_ONDEMAND) + struct irq_desc *desc; + unsigned int i; + + for (i = 0; i < cnt; i++) { + desc = irq_to_desc(start + i); + if (desc && !desc->kstat_irqs) { + unsigned int __percpu *stats = alloc_percpu(unsigned int); + + if (!stats) + return -1; + if (cmpxchg(&desc->kstat_irqs, NULL, stats) != NULL) + free_percpu(stats); + } + } +#endif return start; } #endif /* !CONFIG_SPARSE_IRQ */ @@ -391,7 +409,9 @@ void dynamic_irq_cleanup(unsigned int ir unsigned int kstat_irqs_cpu(unsigned int irq, int cpu) { struct irq_desc *desc = irq_to_desc(irq); - return desc ? desc->kstat_irqs[cpu] : 0; + + return desc && desc->kstat_irqs ? + *per_cpu_ptr(desc->kstat_irqs, cpu) : 0; } #ifdef CONFIG_GENERIC_HARDIRQS @@ -401,10 +421,10 @@ unsigned int kstat_irqs(unsigned int irq int cpu; int sum = 0; - if (!desc) + if (!desc || !desc->kstat_irqs) return 0; for_each_possible_cpu(cpu) - sum += desc->kstat_irqs[cpu]; + sum += *per_cpu_ptr(desc->kstat_irqs, cpu); return sum; } #endif /* CONFIG_GENERIC_HARDIRQS */ _ Patches currently in -mm which might be from eric.dumazet@xxxxxxxxx are origin.patch atomic-add-atomic_inc_not_zero_hint.patch atomic-add-atomic_inc_not_zero_hint-checkpatch-fixes.patch irq-use-per_cpu-kstat_irqs.patch net-avoid-limits-overflow.patch percpucounter-optimize-__percpu_counter_add-a-bit-through-the-use-of-this_cpu-operations.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html