LXR linux/tools/rcu/rcu-cbs.py

   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