In the case of x2apic cluster mode we can group IPI register writes based on the cluster group instead of individual per-cpu destiantion messages. This reduces the apic register writes and reduces the amount of IPI messages (in the best case we can reduce it by a factor of 16). With this change, microbenchmark measuring the cost of flush_tlb_others(), with the flush tlb IPI being sent from a cpu in the socket-1 to all the logical cpus in socket-2 (on a Westmere-EX system that has 20 logical cpus in a socket) is 3x times better now (compared to the former 'send one-by-one' algorithm). v2: Suresh fixed cpumask allocation to be dynamic, stack allocation is not acceptable for such things because can be exhausted. v3: Address Ingo concerns on code style, also a note added just to not forget that we need merge probe_64/32 into some common structure. v4: Suresh discovered (and fixed) that cluster infomation must be updated at CPU_UP_PREPARE state otherwise if IPI happens too early we will be in touble having incomplete cluster sibling map. Tested-by: Suresh Siddha Signed-off-by: Cyrill Gorcunov Acked-by: Suresh Siddha --- arch/x86/include/asm/apic.h | 2 arch/x86/kernel/apic/probe_64.c | 13 ++ arch/x86/kernel/apic/x2apic_cluster.c | 167 ++++++++++++++++++++++++---------- 3 files changed, 136 insertions(+), 46 deletions(-) Index: tip-linux-2.6/arch/x86/include/asm/apic.h =================================================================== --- tip-linux-2.6.orig/arch/x86/include/asm/apic.h +++ tip-linux-2.6/arch/x86/include/asm/apic.h @@ -178,6 +178,8 @@ extern int x2apic_phys; extern void check_x2apic(void); extern void enable_x2apic(void); extern void x2apic_icr_write(u32 low, u32 id); +extern void x2apic_init_cpu_notifier(void); + static inline int x2apic_enabled(void) { u64 msr; Index: tip-linux-2.6/arch/x86/kernel/apic/probe_64.c =================================================================== --- tip-linux-2.6.orig/arch/x86/kernel/apic/probe_64.c +++ tip-linux-2.6/arch/x86/kernel/apic/probe_64.c @@ -55,6 +55,15 @@ static int apicid_phys_pkg_id(int initia void __init default_setup_apic_routing(void) { + /* + * FIXME: + * + * Cleanup the apic routing selection by having an apic driver specific + * selection routine. Then all we need to do here is iterate through + * them to finalize the apic selection. That would get rid of the + * ifdef mess and most of the code here. + */ + enable_IR_x2apic(); #ifdef CONFIG_X86_X2APIC @@ -71,7 +80,9 @@ void __init default_setup_apic_routing(v #endif if (apic == &apic_flat && num_possible_cpus() > 8) - apic = &apic_physflat; + apic = &apic_physflat; + else if (apic == &apic_x2apic_cluster) + x2apic_init_cpu_notifier(); printk(KERN_INFO "Setting APIC routing to %s\n", apic->name); Index: tip-linux-2.6/arch/x86/kernel/apic/x2apic_cluster.c =================================================================== --- tip-linux-2.6.orig/arch/x86/kernel/apic/x2apic_cluster.c +++ tip-linux-2.6/arch/x86/kernel/apic/x2apic_cluster.c @@ -5,12 +5,15 @@ #include #include #include +#include #include #include #include static DEFINE_PER_CPU(u32, x86_cpu_to_logical_apicid); +static DEFINE_PER_CPU(cpumask_var_t, cpus_in_cluster); +static DEFINE_PER_CPU(cpumask_var_t, ipi_mask); static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id) { @@ -36,7 +39,7 @@ static void x2apic_vector_allocation_dom } static void - __x2apic_send_IPI_dest(unsigned int apicid, int vector, unsigned int dest) +__x2apic_send_IPI_dest(unsigned int apicid, int vector, unsigned int dest) { unsigned long cfg; @@ -48,70 +51,80 @@ static void native_x2apic_icr_write(cfg, apicid); } -/* - * for now, we send the IPI's one by one in the cpumask. - * TBD: Based on the cpu mask, we can send the IPI's to the cluster group - * at once. We have 16 cpu's in a cluster. This will minimize IPI register - * writes. - */ -static void x2apic_send_IPI_mask(const struct cpumask *mask, int vector) +static inline u32 x2apic_cluster(int cpu) { - unsigned long query_cpu; - unsigned long flags; - - x2apic_wrmsr_fence(); - - local_irq_save(flags); - for_each_cpu(query_cpu, mask) { - __x2apic_send_IPI_dest( - per_cpu(x86_cpu_to_logical_apicid, query_cpu), - vector, apic->dest_logical); - } - local_irq_restore(flags); + return per_cpu(x86_cpu_to_logical_apicid, cpu) >> 16; } static void - x2apic_send_IPI_mask_allbutself(const struct cpumask *mask, int vector) +__x2apic_send_IPI_mask(const struct cpumask *mask, int vector, int exclude_self) { - unsigned long this_cpu = smp_processor_id(); - unsigned long query_cpu; + struct cpumask *cpus_in_cluster_ptr; + struct cpumask *ipi_mask_ptr; + unsigned int cpu, this_cpu; unsigned long flags; + u32 dest; x2apic_wrmsr_fence(); local_irq_save(flags); - for_each_cpu(query_cpu, mask) { - if (query_cpu == this_cpu) + this_cpu = smp_processor_id(); + + /* + * We are to modify mask, so we need an own copy + * and be sure it's manipulated with irq off. + */ + ipi_mask_ptr = __raw_get_cpu_var(ipi_mask); + cpumask_copy(ipi_mask_ptr, mask); + + /* + * The idea is to send one IPI per cluster. + */ + for_each_cpu(cpu, ipi_mask_ptr) { + unsigned long i; + + cpus_in_cluster_ptr = per_cpu(cpus_in_cluster, cpu); + dest = 0; + + /* Collect cpus in cluster. */ + for_each_cpu_and(i, ipi_mask_ptr, cpus_in_cluster_ptr) { + if (!exclude_self || i != this_cpu) + dest |= per_cpu(x86_cpu_to_logical_apicid, i); + } + + if (!dest) continue; - __x2apic_send_IPI_dest( - per_cpu(x86_cpu_to_logical_apicid, query_cpu), - vector, apic->dest_logical); + + __x2apic_send_IPI_dest(dest, vector, apic->dest_logical); + /* + * Cluster sibling cpus should be discared now so + * we would not send IPI them second time. + */ + cpumask_andnot(ipi_mask_ptr, ipi_mask_ptr, cpus_in_cluster_ptr); } + local_irq_restore(flags); } -static void x2apic_send_IPI_allbutself(int vector) +static void +x2apic_send_IPI_mask_allbutself(const struct cpumask *mask, int vector) { - unsigned long this_cpu = smp_processor_id(); - unsigned long query_cpu; - unsigned long flags; + __x2apic_send_IPI_mask(mask, vector, 1); +} - x2apic_wrmsr_fence(); +static void x2apic_send_IPI_allbutself(int vector) +{ + __x2apic_send_IPI_mask(cpu_online_mask, vector, 1); +} - local_irq_save(flags); - for_each_online_cpu(query_cpu) { - if (query_cpu == this_cpu) - continue; - __x2apic_send_IPI_dest( - per_cpu(x86_cpu_to_logical_apicid, query_cpu), - vector, apic->dest_logical); - } - local_irq_restore(flags); +static void x2apic_send_IPI_mask(const struct cpumask *mask, int vector) +{ + __x2apic_send_IPI_mask(mask, vector, 0); } static void x2apic_send_IPI_all(int vector) { - x2apic_send_IPI_mask(cpu_online_mask, vector); + __x2apic_send_IPI_mask(cpu_online_mask, vector, 0); } static int x2apic_apic_id_registered(void) @@ -151,6 +164,7 @@ x2apic_cpu_mask_to_apicid_and(const stru return per_cpu(x86_cpu_to_logical_apicid, cpu); } + static unsigned int x2apic_cluster_phys_get_apic_id(unsigned long x) { unsigned int id; @@ -179,13 +193,76 @@ static void x2apic_send_IPI_self(int vec static void init_x2apic_ldr(void) { + unsigned int this_cpu = smp_processor_id(); + unsigned int cpu; + + per_cpu(x86_cpu_to_logical_apicid, this_cpu) = apic_read(APIC_LDR); + + __cpu_set(this_cpu, per_cpu(cpus_in_cluster, this_cpu)); + for_each_online_cpu(cpu) { + if (x2apic_cluster(this_cpu) != x2apic_cluster(cpu)) + continue; + __cpu_set(this_cpu, per_cpu(cpus_in_cluster, cpu)); + __cpu_set(cpu, per_cpu(cpus_in_cluster, this_cpu)); + } +} + +/* + * At CPU state changes, update the x2apic cluster sibling info. + */ +static int __cpuinit +update_clusterinfo(struct notifier_block *nfb, unsigned long action, void *hcpu) +{ + unsigned int this_cpu = (unsigned long)hcpu; + unsigned int cpu; + int err = 0; + + switch (action) { + case CPU_UP_PREPARE: + if (!zalloc_cpumask_var(&per_cpu(cpus_in_cluster, this_cpu), + GFP_KERNEL)) { + err = -ENOMEM; + } else if (!zalloc_cpumask_var(&per_cpu(ipi_mask, this_cpu), + GFP_KERNEL)) { + free_cpumask_var(per_cpu(cpus_in_cluster, this_cpu)); + err = -ENOMEM; + } + break; + case CPU_UP_CANCELED: + case CPU_UP_CANCELED_FROZEN: + case CPU_DEAD: + for_each_online_cpu(cpu) { + if (x2apic_cluster(this_cpu) != x2apic_cluster(cpu)) + continue; + __cpu_clear(this_cpu, per_cpu(cpus_in_cluster, cpu)); + __cpu_clear(cpu, per_cpu(cpus_in_cluster, this_cpu)); + } + free_cpumask_var(per_cpu(cpus_in_cluster, this_cpu)); + free_cpumask_var(per_cpu(ipi_mask, this_cpu)); + break; + } + + return notifier_from_errno(err); +} + +static struct notifier_block __refdata x2apic_cpu_notifier = { + .notifier_call = update_clusterinfo, +}; + +void x2apic_init_cpu_notifier(void) +{ int cpu = smp_processor_id(); - per_cpu(x86_cpu_to_logical_apicid, cpu) = apic_read(APIC_LDR); + zalloc_cpumask_var(&per_cpu(cpus_in_cluster, cpu), GFP_KERNEL); + zalloc_cpumask_var(&per_cpu(ipi_mask, cpu), GFP_KERNEL); + + BUG_ON(!per_cpu(cpus_in_cluster, cpu) || !per_cpu(ipi_mask, cpu)); + + __cpu_set(cpu, per_cpu(cpus_in_cluster, cpu)); + register_hotcpu_notifier(&x2apic_cpu_notifier); } struct apic apic_x2apic_cluster = { - .name = "cluster x2apic", .probe = NULL, .acpi_madt_oem_check = x2apic_acpi_madt_oem_check, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/