From 4ca234a9cbd7c3a656b34dd98c8b156f70ed7849 Mon Sep 17 00:00:00 2001 From: Srikar Dronamraju Date: Mon, 21 Sep 2020 15:26:44 +0530 Subject: [PATCH] powerpc/smp: Stop updating cpu_core_mask Anton Blanchard reported that his 4096 vcpu KVM guest took around 30 minutes to boot. He also analyzed it to the time taken to iterate while setting the cpu_core_mask. Further analysis shows that cpu_core_mask and cpu_cpu_mask for any CPU would be equal on Power. However updating cpu_core_mask took forever to update as its a per cpu cpumask variable. Instead cpu_cpu_mask was a per NODE /per DIE cpumask that was shared by all the respective CPUs. Also cpu_cpu_mask is needed from a scheduler perspective. However cpu_core_map is an exported symbol. Hence stop updating cpu_core_map and make it point to cpu_cpu_mask. Signed-off-by: Srikar Dronamraju Tested-by: Satheesh Rajendran Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200921095653.9701-3-srikar@linux.vnet.ibm.com --- arch/powerpc/include/asm/smp.h | 5 ----- arch/powerpc/kernel/smp.c | 33 +++++++-------------------------- 2 files changed, 7 insertions(+), 31 deletions(-) diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h index 635bdf947105..b2035b2f57ce 100644 --- a/arch/powerpc/include/asm/smp.h +++ b/arch/powerpc/include/asm/smp.h @@ -121,11 +121,6 @@ static inline struct cpumask *cpu_sibling_mask(int cpu) return per_cpu(cpu_sibling_map, cpu); } -static inline struct cpumask *cpu_core_mask(int cpu) -{ - return per_cpu(cpu_core_map, cpu); -} - static inline struct cpumask *cpu_l2_cache_mask(int cpu) { return per_cpu(cpu_l2_cache_map, cpu); diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index 58990baa5182..bf6d4192adda 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -953,12 +953,17 @@ void __init smp_prepare_cpus(unsigned int max_cpus) local_memory_node(numa_cpu_lookup_table[cpu])); } #endif + /* + * cpu_core_map is now more updated and exists only since + * its been exported for long. It only will have a snapshot + * of cpu_cpu_mask. + */ + cpumask_copy(per_cpu(cpu_core_map, cpu), cpu_cpu_mask(cpu)); } /* Init the cpumasks so the boot CPU is related to itself */ cpumask_set_cpu(boot_cpuid, cpu_sibling_mask(boot_cpuid)); cpumask_set_cpu(boot_cpuid, cpu_l2_cache_mask(boot_cpuid)); - cpumask_set_cpu(boot_cpuid, cpu_core_mask(boot_cpuid)); if (has_coregroup_support()) cpumask_set_cpu(boot_cpuid, cpu_coregroup_mask(boot_cpuid)); @@ -1260,9 +1265,7 @@ static void remove_cpu_from_masks(int cpu) { int i; - /* NB: cpu_core_mask is a superset of the others */ - for_each_cpu(i, cpu_core_mask(cpu)) { - set_cpus_unrelated(cpu, i, cpu_core_mask); + for_each_cpu(i, cpu_cpu_mask(cpu)) { set_cpus_unrelated(cpu, i, cpu_l2_cache_mask); set_cpus_unrelated(cpu, i, cpu_sibling_mask); if (has_big_cores) @@ -1312,7 +1315,6 @@ EXPORT_SYMBOL_GPL(get_physical_package_id); static void add_cpu_to_masks(int cpu) { int first_thread = cpu_first_thread_sibling(cpu); - int pkg_id = get_physical_package_id(cpu); int i; /* @@ -1320,7 +1322,6 @@ static void add_cpu_to_masks(int cpu) * add it to it's own thread sibling mask. */ cpumask_set_cpu(cpu, cpu_sibling_mask(cpu)); - cpumask_set_cpu(cpu, cpu_core_mask(cpu)); for (i = first_thread; i < first_thread + threads_per_core; i++) if (cpu_online(i)) @@ -1342,26 +1343,6 @@ static void add_cpu_to_masks(int cpu) set_cpus_related(cpu, i, cpu_coregroup_mask); } } - - if (pkg_id == -1) { - struct cpumask *(*mask)(int) = cpu_sibling_mask; - - /* - * Copy the sibling mask into core sibling mask and - * mark any CPUs on the same chip as this CPU. - */ - if (shared_caches) - mask = cpu_l2_cache_mask; - - for_each_cpu(i, mask(cpu)) - set_cpus_related(cpu, i, cpu_core_mask); - - return; - } - - for_each_cpu(i, cpu_online_mask) - if (get_physical_package_id(i) == pkg_id) - set_cpus_related(cpu, i, cpu_core_mask); } /* Activate a secondary processor. */