From caa8e29da59926bef099b46ab6280333d583e944 Mon Sep 17 00:00:00 2001 From: Srikar Dronamraju Date: Mon, 10 Aug 2020 12:48:30 +0530 Subject: [PATCH] powerpc/smp: Optimize start_secondary In start_secondary, even if shared_cache was already set, system does a redundant match for cpumask. This redundant check can be removed by checking if shared_cache is already set. While here, localize the sibling_mask variable to within the if condition. Signed-off-by: Srikar Dronamraju Reviewed-by: Gautham R. Shenoy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200810071834.92514-7-srikar@linux.vnet.ibm.com --- arch/powerpc/kernel/smp.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index 168532e37305..016a822eb8c4 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -852,7 +852,7 @@ static int powerpc_shared_cache_flags(void) */ static const struct cpumask *shared_cache_mask(int cpu) { - return cpu_l2_cache_mask(cpu); + return per_cpu(cpu_l2_cache_map, cpu); } #ifdef CONFIG_SCHED_SMT @@ -1319,7 +1319,6 @@ static void add_cpu_to_masks(int cpu) void start_secondary(void *unused) { unsigned int cpu = smp_processor_id(); - struct cpumask *(*sibling_mask)(int) = cpu_sibling_mask; mmgrab(&init_mm); current->active_mm = &init_mm; @@ -1345,14 +1344,20 @@ void start_secondary(void *unused) /* Update topology CPU masks */ add_cpu_to_masks(cpu); - if (has_big_cores) - sibling_mask = cpu_smallcore_mask; /* * Check for any shared caches. Note that this must be done on a * per-core basis because one core in the pair might be disabled. */ - if (!cpumask_equal(cpu_l2_cache_mask(cpu), sibling_mask(cpu))) - shared_caches = true; + if (!shared_caches) { + struct cpumask *(*sibling_mask)(int) = cpu_sibling_mask; + struct cpumask *mask = cpu_l2_cache_mask(cpu); + + if (has_big_cores) + sibling_mask = cpu_smallcore_mask; + + if (cpumask_weight(mask) > cpumask_weight(sibling_mask(cpu))) + shared_caches = true; + } set_numa_node(numa_cpu_lookup_table[cpu]); set_numa_mem(local_memory_node(numa_cpu_lookup_table[cpu])); -- 2.11.0