From e75bcd48e2c4026b1f3feda916a2327b1744d664 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Tue, 23 Feb 2021 01:10:11 +0100 Subject: rcu/nocb: Unify timers Now that ->nocb_timer and ->nocb_bypass_timer have become quite similar, this commit merges them together. A new RCU_NOCB_WAKE_BYPASS wake level is introduced. As a result, timers perform all kinds of deferred wake ups but other deferred wakeup callsites only handle non-bypass wakeups in order not to wake up rcuo too early. The timer also unconditionally executes a full barrier so as to order timer_pending() and callback enqueue although the path performing RCU_NOCB_WAKE_FORCE that makes use of it is debatable. It should also test against the rdp leader instead of the current rdp. This unconditional full barrier shouldn't bring visible overhead since these timers almost never fire. Signed-off-by: Frederic Weisbecker Cc: Josh Triplett Cc: Lai Jiangshan Cc: Joel Fernandes Cc: Neeraj Upadhyay Cc: Boqun Feng Signed-off-by: Paul E. McKenney --- include/trace/events/rcu.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/trace') diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h index 6768b64bc738..670e41783edd 100644 --- a/include/trace/events/rcu.h +++ b/include/trace/events/rcu.h @@ -278,6 +278,7 @@ TRACE_EVENT_RCU(rcu_exp_funnel_lock, * "WakeNot": Don't wake rcuo kthread. * "WakeNotPoll": Don't wake rcuo kthread because it is polling. * "WakeOvfIsDeferred": Wake rcuo kthread later, CB list is huge. + * "WakeBypassIsDeferred": Wake rcuo kthread later, bypass list is contended. * "WokeEmpty": rcuo CB kthread woke to find empty list. */ TRACE_EVENT_RCU(rcu_nocb_wake, -- cgit v1.2.3-70-g09d2