Commit-ID: 28728dd310d48834cd486dac3cac9ae96b9deb96
Gitweb: http://git.kernel.org/tip/28728dd310d48834cd486dac3cac9ae96b9deb96
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Tue, 12 Jan 2016 08:33:37 -0800
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Thu, 31 Mar 2016 13:34:03 -0700
rcu: Make expedited RCU-sched grace period immediately detect idle
Currently, sync_sched_exp_handler() will force a reschedule unless
this CPU has already checked in or unless a reschedule has already
been called for. This is clearly wasteful if sync_sched_exp_handler()
interrupted an idle CPU, so this commit immediately reports the
quiescent state in that case.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/rcu/tree.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 531a328..5f4336f 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3649,6 +3649,11 @@ static void sync_sched_exp_handler(void *data)
if (!(READ_ONCE(rnp->expmask) & rdp->grpmask) ||
__this_cpu_read(rcu_sched_data.cpu_no_qs.b.exp))
return;
+ if (rcu_is_cpu_rrupt_from_idle()) {
+ rcu_report_exp_rdp(&rcu_sched_state,
+ this_cpu_ptr(&rcu_sched_data), true);
+ return;
+ }
__this_cpu_write(rcu_sched_data.cpu_no_qs.b.exp, true);
resched_cpu(smp_processor_id());
}
--
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