Messages in this thread Patch in this message | | | From | Yury Norov <> | Subject | [PATCH 22/54] rcu: replace cpumask_weight with cpumask_empty where appropriate | Date | Sun, 23 Jan 2022 10:38:53 -0800 |
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In some places, RCU code calls cpumask_weight() to check if any bit of a given cpumask is set. We can do it more efficiently with cpumask_empty() because cpumask_empty() stops traversing the cpumask as soon as it finds first set bit, while cpumask_weight() counts all bits unconditionally.
Signed-off-by: Yury Norov <yury.norov@gmail.com> --- kernel/rcu/tree_nocb.h | 4 ++-- kernel/rcu/tree_plugin.h | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h index eeafb546a7a0..f83c7b1d6110 100644 --- a/kernel/rcu/tree_nocb.h +++ b/kernel/rcu/tree_nocb.h @@ -1169,7 +1169,7 @@ void __init rcu_init_nohz(void) struct rcu_data *rdp; #if defined(CONFIG_NO_HZ_FULL) - if (tick_nohz_full_running && cpumask_weight(tick_nohz_full_mask)) + if (tick_nohz_full_running && !cpumask_empty(tick_nohz_full_mask)) need_rcu_nocb_mask = true; #endif /* #if defined(CONFIG_NO_HZ_FULL) */ @@ -1348,7 +1348,7 @@ static void __init rcu_organize_nocb_kthreads(void) */ void rcu_bind_current_to_nocb(void) { - if (cpumask_available(rcu_nocb_mask) && cpumask_weight(rcu_nocb_mask)) + if (cpumask_available(rcu_nocb_mask) && !cpumask_empty(rcu_nocb_mask)) WARN_ON(sched_setaffinity(current->pid, rcu_nocb_mask)); } EXPORT_SYMBOL_GPL(rcu_bind_current_to_nocb); diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index c5b45c2f68a1..0dc0c8d6717c 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1215,7 +1215,7 @@ static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu) cpu != outgoingcpu) cpumask_set_cpu(cpu, cm); cpumask_and(cm, cm, housekeeping_cpumask(HK_FLAG_RCU)); - if (cpumask_weight(cm) == 0) + if (cpumask_empty(cm)) cpumask_copy(cm, housekeeping_cpumask(HK_FLAG_RCU)); set_cpus_allowed_ptr(t, cm); free_cpumask_var(cm); -- 2.30.2
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