Commit 80d530b4 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Print number of online CPUs in RCU CPU stall-warning messages 



RCU's synchronous grace periods act quite differently when there is
only one online CPU, especially in the no-op case in kernels built with
CONFIG_PREEMPTION=n.  This change in behavior can be important debugging
information, so this commit adds the number of online CPUs to the RCU
CPU stall warning messages.

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 75182a4e

kernel/rcu/tree_stall.h

+4 −4
Original line number Diff line number Diff line
@@ -565,9 +565,9 @@ static void print_other_cpu_stall(unsigned long gp_seq, unsigned long gps) 


	for_each_possible_cpu(cpu)

		totqlen += rcu_get_n_cbs_cpu(cpu);

	pr_cont("\t(detected by %d, t=%ld jiffies, g=%ld, q=%lu)\n",

	pr_cont("\t(detected by %d, t=%ld jiffies, g=%ld, q=%lu ncpus=%d)\n",

	       smp_processor_id(), (long)(jiffies - gps),

	       (long)rcu_seq_current(&rcu_state.gp_seq), totqlen);

	       (long)rcu_seq_current(&rcu_state.gp_seq), totqlen, rcu_state.n_online_cpus);

	if (ndetected) {

		rcu_dump_cpu_stacks();
@@ -626,9 +626,9 @@ static void print_cpu_stall(unsigned long gps) 
	raw_spin_unlock_irqrestore_rcu_node(rdp->mynode, flags);

	for_each_possible_cpu(cpu)

		totqlen += rcu_get_n_cbs_cpu(cpu);

	pr_cont("\t(t=%lu jiffies g=%ld q=%lu)\n",

	pr_cont("\t(t=%lu jiffies g=%ld q=%lu ncpus=%d)\n",

		jiffies - gps,

		(long)rcu_seq_current(&rcu_state.gp_seq), totqlen);

		(long)rcu_seq_current(&rcu_state.gp_seq), totqlen, rcu_state.n_online_cpus);



	rcu_check_gp_kthread_expired_fqs_timer();

	rcu_check_gp_kthread_starvation();