From 69a79bb12a81024d718e73c52e886907a3777b34 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 15 Aug 2013 13:23:23 -0700 Subject: rcu: Track rcu_nocb_kthread()'s sleeping and awakening This commit adds event traces to track all of rcu_nocb_kthread()'s blocking and awakening. Signed-off-by: Paul E. McKenney --- include/trace/events/rcu.h | 4 ++++ kernel/rcutree_plugin.h | 15 ++++++++++++++- 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h index 4301cd9e3ee5..a087d82ed431 100644 --- a/include/trace/events/rcu.h +++ b/include/trace/events/rcu.h @@ -183,8 +183,12 @@ TRACE_EVENT(rcu_grace_period_init, * "WakeOvf": Wake rcuo kthread, CB list is huge. * "WakeNot": Don't wake rcuo kthread. * "WakeNotPoll": Don't wake rcuo kthread because it is polling. + * "Poll": Start of new polling cycle for rcu_nocb_poll. + * "Sleep": Sleep waiting for CBs for !rcu_nocb_poll. * "WokeEmpty": rcuo kthread woke to find empty list. * "WokeNonEmpty": rcuo kthread woke to find non-empty list. + * "WaitQueue": Enqueue partially done, timed wait for it to complete. + * "WokeQueue": Partial enqueue now complete. */ TRACE_EVENT(rcu_nocb_wake, diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 24b01b69be92..21205b185340 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -2230,6 +2230,7 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp) static int rcu_nocb_kthread(void *arg) { int c, cl; + bool firsttime = 1; struct rcu_head *list; struct rcu_head *next; struct rcu_head **tail; @@ -2238,8 +2239,15 @@ static int rcu_nocb_kthread(void *arg) /* Each pass through this loop invokes one batch of callbacks */ for (;;) { /* If not polling, wait for next batch of callbacks. */ - if (!rcu_nocb_poll) + if (!rcu_nocb_poll) { + trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu, + TPS("Sleep")); wait_event_interruptible(rdp->nocb_wq, rdp->nocb_head); + } else if (firsttime) { + firsttime = 0; + trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu, + TPS("Poll")); + } list = ACCESS_ONCE(rdp->nocb_head); if (!list) { if (!rcu_nocb_poll) @@ -2249,6 +2257,7 @@ static int rcu_nocb_kthread(void *arg) flush_signals(current); continue; } + firsttime = 1; trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu, TPS("WokeNonEmpty")); @@ -2271,7 +2280,11 @@ static int rcu_nocb_kthread(void *arg) next = list->next; /* Wait for enqueuing to complete, if needed. */ while (next == NULL && &list->next != tail) { + trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu, + TPS("WaitQueue")); schedule_timeout_interruptible(1); + trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu, + TPS("WokeQueue")); next = list->next; } debug_rcu_head_unqueue(list); -- cgit v1.2.3