diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-06-30 15:23:37 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-08-30 16:02:38 -0700 |
| commit | ba1c64c27239373be1b3d88cf0a9ac1b10fa871f (patch) | |
| tree | 213989e0ed3d4c35f86efd1f1f4248634ab80e06 | |
| parent | d28139c4e96713d52a300fb9036c5be2f45e0741 (diff) | |
rcu: Report expedited grace periods at context-switch time
This commit reduces the latency of expedited RCU grace periods by
reporting a quiescent state for the CPU at context-switch time.
In CONFIG_PREEMPT=y kernels, if the outgoing task is still within an
RCU read-side critical section (and thus still blocking some grace
period, perhaps including this expedited grace period), then that task
will already have been placed on one of the leaf rcu_node structures'
->blkd_tasks list.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index c686bf63bba5..0d7107fb3dec 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -332,7 +332,7 @@ static void rcu_preempt_qs(void) static void rcu_preempt_note_context_switch(bool preempt) { struct task_struct *t = current; - struct rcu_data *rdp; + struct rcu_data *rdp = this_cpu_ptr(rcu_state_p->rda); struct rcu_node *rnp; lockdep_assert_irqs_disabled(); @@ -341,7 +341,6 @@ static void rcu_preempt_note_context_switch(bool preempt) !t->rcu_read_unlock_special.b.blocked) { /* Possibly blocking in an RCU read-side critical section. */ - rdp = this_cpu_ptr(rcu_state_p->rda); rnp = rdp->mynode; raw_spin_lock_rcu_node(rnp); t->rcu_read_unlock_special.b.blocked = true; @@ -383,6 +382,8 @@ static void rcu_preempt_note_context_switch(bool preempt) * means that we continue to block the current grace period. */ rcu_preempt_qs(); + if (rdp->deferred_qs) + rcu_report_exp_rdp(rcu_state_p, rdp, true); } /* |