47 lines · python
1#!/usr/bin/env drgn2# 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 the7# number of callbacks for the most heavily used flavor.8#9# Usage: sudo drgn rcu-cbs.py10#11# Copyright (C) 2021 Facebook, Inc.12#13# Authors: Paul E. McKenney <paulmck@kernel.org>14 15import sys16import drgn17from drgn import NULL, Object18from 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