From 70edd4a7c753ba18e3e4bb9e97b6d85156cea738 Mon Sep 17 00:00:00 2001 From: Srikar Dronamraju Date: Mon, 21 Sep 2020 15:26:46 +0530 Subject: powerpc/smp: Optimize remove_cpu_from_masks While offlining a CPU, system currently iterate through all the CPUs in the DIE to clear sibling, l2_cache and smallcore maps. However if there are more cores in a DIE, system can end up spending more time iterating through CPUs which are completely unrelated. Optimize this by only iterating through smaller but relevant cpumap. If shared_cache is set, cpu_l2_cache_map should be relevant else cpu_sibling_map would be relevant. Signed-off-by: Srikar Dronamraju Tested-by: Satheesh Rajendran Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200921095653.9701-5-srikar@linux.vnet.ibm.com --- arch/powerpc/kernel/smp.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'arch/powerpc/kernel') diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index aecc01f0e95e..9cdb966f00b3 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -1263,14 +1263,21 @@ static bool update_mask_by_l2(int cpu, struct cpumask *(*mask_fn)(int)) #ifdef CONFIG_HOTPLUG_CPU static void remove_cpu_from_masks(int cpu) { + struct cpumask *(*mask_fn)(int) = cpu_sibling_mask; int i; - for_each_cpu(i, cpu_cpu_mask(cpu)) { + if (shared_caches) + mask_fn = cpu_l2_cache_mask; + + for_each_cpu(i, mask_fn(cpu)) { set_cpus_unrelated(cpu, i, cpu_l2_cache_mask); set_cpus_unrelated(cpu, i, cpu_sibling_mask); if (has_big_cores) set_cpus_unrelated(cpu, i, cpu_smallcore_mask); - if (has_coregroup_support()) + } + + if (has_coregroup_support()) { + for_each_cpu(i, cpu_coregroup_mask(cpu)) set_cpus_unrelated(cpu, i, cpu_coregroup_mask); } } -- cgit v1.2.3