From c669c014d1dae9c7cdbfff049c798722f8650829 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 2 Oct 2018 12:42:21 -0700 Subject: [PATCH] rcu: Add jiffies-since-GP-activity to show_rcu_gp_kthreads() This commit adds a printout of the number of jiffies since the last time that the RCU grace-period kthread did any processing. This can be useful when tracking down forward-progress issues. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index ea78532183ac..e7c9848d1e1b 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -515,12 +515,14 @@ static const char *gp_state_getname(short gs) void show_rcu_gp_kthreads(void) { int cpu; + unsigned long j; struct rcu_data *rdp; struct rcu_node *rnp; - pr_info("%s: wait state: %s(%d) ->state: %#lx\n", rcu_state.name, - gp_state_getname(rcu_state.gp_state), rcu_state.gp_state, - rcu_state.gp_kthread->state); + j = jiffies - READ_ONCE(rcu_state.gp_activity); + pr_info("%s: wait state: %s(%d) ->state: %#lx delta ->gp_activity %ld\n", + rcu_state.name, gp_state_getname(rcu_state.gp_state), + rcu_state.gp_state, rcu_state.gp_kthread->state, j); rcu_for_each_node_breadth_first(rnp) { if (ULONG_CMP_GE(rcu_state.gp_seq, rnp->gp_seq_needed)) continue;