Messages in this thread Patch in this message | | | From | Zqiang <> | Subject | [PATCH] rcu: Only boost rcu reader tasks with lower priority than boost kthreads | Date | Fri, 4 Mar 2022 17:26:31 +0800 |
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When RCU_BOOST is enabled, the boost kthreads will boosting readers who are blocking a given grace period, if the current reader tasks have a higher priority than boost kthreads(the boost kthreads priority not always 1, if the kthread_prio is set), boosting is useless, skip current task and select next task to boosting, reduce the time for a given grace period.
Signed-off-by: Zqiang <qiang1.zhang@intel.com> --- kernel/rcu/tree_plugin.h | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index c3d212bc5338..d35b6da66bbd 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -12,6 +12,7 @@ */ #include "../locking/rtmutex_common.h" +#include <linux/sched/deadline.h> static bool rcu_rdp_is_offloaded(struct rcu_data *rdp) { @@ -1065,13 +1066,20 @@ static int rcu_boost(struct rcu_node *rnp) * section. */ t = container_of(tb, struct task_struct, rcu_node_entry); + if (!rnp->exp_tasks && (dl_task(t) || t->prio <= current->prio)) { + tb = rcu_next_node_entry(t, rnp); + WRITE_ONCE(rnp->boost_tasks, tb); + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + goto end; + } + rt_mutex_init_proxy_locked(&rnp->boost_mtx.rtmutex, t); raw_spin_unlock_irqrestore_rcu_node(rnp, flags); /* Lock only for side effect: boosts task t's priority. */ rt_mutex_lock(&rnp->boost_mtx); rt_mutex_unlock(&rnp->boost_mtx); /* Then keep lockdep happy. */ rnp->n_boosts++; - +end: return READ_ONCE(rnp->exp_tasks) != NULL || READ_ONCE(rnp->boost_tasks) != NULL; } -- 2.25.1
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