From 70a94089d7f7fa91bc1795622426b3ed017ec71a Mon Sep 17 00:00:00 2001 From: Srikar Dronamraju Date: Mon, 21 Sep 2020 15:26:53 +0530 Subject: [PATCH] powerpc/smp: Optimize update_coregroup_mask All threads of a SMT4/SMT8 core can either be part of CPU's coregroup mask or outside the coregroup. Use this relation to reduce the number of iterations needed to find all the CPUs that share the same coregroup Use a temporary mask to iterate through the CPUs that may share coregroup mask. Also instead of setting one CPU at a time into cpu_coregroup_mask, copy the SMT4/SMT8/submask at one shot. Signed-off-by: Srikar Dronamraju Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200921095653.9701-12-srikar@linux.vnet.ibm.com --- arch/powerpc/kernel/smp.c | 30 ++++++++++++++++++++++-------- 1 file changed, 22 insertions(+), 8 deletions(-) diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index 45619433c43ae..0dc1b8591cc88 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -1339,19 +1339,33 @@ static inline void add_cpu_to_smallcore_masks(int cpu) static void update_coregroup_mask(int cpu) { - int first_thread = cpu_first_thread_sibling(cpu); + struct cpumask *(*submask_fn)(int) = cpu_sibling_mask; + cpumask_var_t mask; int coregroup_id = cpu_to_coregroup_id(cpu); int i; - cpumask_set_cpu(cpu, cpu_coregroup_mask(cpu)); - for_each_cpu_and(i, cpu_online_mask, cpu_cpu_mask(cpu)) { - int fcpu = cpu_first_thread_sibling(i); + alloc_cpumask_var_node(&mask, GFP_KERNEL, cpu_to_node(cpu)); + cpumask_and(mask, cpu_online_mask, cpu_cpu_mask(cpu)); + + if (shared_caches) + submask_fn = cpu_l2_cache_mask; + + /* Update coregroup mask with all the CPUs that are part of submask */ + or_cpumasks_related(cpu, cpu, submask_fn, cpu_coregroup_mask); + + /* Skip all CPUs already part of coregroup mask */ + cpumask_andnot(mask, mask, cpu_coregroup_mask(cpu)); - if (fcpu == first_thread) - set_cpus_related(cpu, i, cpu_coregroup_mask); - else if (coregroup_id == cpu_to_coregroup_id(i)) - set_cpus_related(cpu, i, cpu_coregroup_mask); + for_each_cpu(i, mask) { + /* Skip all CPUs not part of this coregroup */ + if (coregroup_id == cpu_to_coregroup_id(i)) { + or_cpumasks_related(cpu, i, submask_fn, cpu_coregroup_mask); + cpumask_andnot(mask, mask, submask_fn(i)); + } else { + cpumask_andnot(mask, mask, cpu_coregroup_mask(i)); + } } + free_cpumask_var(mask); } static void add_cpu_to_masks(int cpu) -- 2.30.2