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 <paulmck@linux.ibm.com>
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index ea78532..e7c9848 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -515,12 +515,14 @@
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;
