1#!/usr/bin/env drgn 2# SPDX-License-Identifier: GPL-2.0+ 3# 4# Dump out the number of RCU callbacks outstanding. 5# 6# On older kernels having multiple flavors of RCU, this dumps out the 7# number of callbacks for the most heavily used flavor. 8# 9# Usage: sudo drgn rcu-cbs.py 10# 11# Copyright (C) 2021 Facebook, Inc. 12# 13# Authors: Paul E. McKenney <paulmck@kernel.org> 14 15import sys 16import drgn 17from drgn import NULL, Object 18from drgn.helpers.linux import * 19 20def get_rdp0(prog): 21 try: 22 rdp0 = prog.variable('rcu_preempt_data', 'kernel/rcu/tree.c'); 23 except LookupError: 24 rdp0 = NULL; 25 26 if rdp0 == NULL: 27 try: 28 rdp0 = prog.variable('rcu_sched_data', 29 'kernel/rcu/tree.c'); 30 except LookupError: 31 rdp0 = NULL; 32 33 if rdp0 == NULL: 34 rdp0 = prog.variable('rcu_data', 'kernel/rcu/tree.c'); 35 return rdp0.address_of_(); 36 37rdp0 = get_rdp0(prog); 38 39# Sum up RCU callbacks. 40sum = 0; 41for cpu in for_each_possible_cpu(prog): 42 rdp = per_cpu_ptr(rdp0, cpu); 43 len = rdp.cblist.len.value_(); 44 # print("CPU " + str(cpu) + " RCU callbacks: " + str(len)); 45 sum += len; 46print("Number of RCU callbacks in flight: " + str(sum)); 47