Currently while offlining a cpu, we iterate through all the cpus in the DIE to clear sibling, l2_cache and smallcore maps. However if there are more number of cores in a DIE, we end up spending more time iterating through cpus which are completely unrelated.
Optimize this by only iterating through lesser but relevant cpumap. If shared_cache is set, cpu_l2_cache_map should be relevant else cpu_sibling_map would be relevant. Cc: linuxppc-dev <[email protected]> Cc: LKML <[email protected]> Cc: Michael Ellerman <[email protected]> Cc: Nicholas Piggin <[email protected]> Cc: Anton Blanchard <[email protected]> Cc: Oliver O'Halloran <[email protected]> Cc: Nathan Lynch <[email protected]> Cc: Michael Neuling <[email protected]> Cc: Gautham R Shenoy <[email protected]> Cc: Satheesh Rajendran <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Valentin Schneider <[email protected]> Signed-off-by: Srikar Dronamraju <[email protected]> --- arch/powerpc/kernel/smp.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index d476098fc25c..cde157483abf 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -1254,14 +1254,21 @@ 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); } } -- 2.17.1
