From: Paul E. McKenney Date: Fri, 11 Mar 2022 18:10:35 +0000 (-0800) Subject: rcu: Print number of online CPUs in RCU CPU stall-warning messages X-Git-Tag: v5.19-rc1~252^2~1^2~4 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=80d530b47da41642fab317a9485d58dfbe1e8896;p=thirdparty%2Fkernel%2Flinux.git 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: Paul E. McKenney --- diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 0c5d8516516af..268dd79c58e72 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -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();