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-rw-r--r--tools/rcu/rcu-cbs.py46
1 files changed, 46 insertions, 0 deletions
diff --git a/tools/rcu/rcu-cbs.py b/tools/rcu/rcu-cbs.py
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+#!/usr/bin/env drgn
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Dump out the number of RCU callbacks outstanding.
+#
+# On older kernels having multiple flavors of RCU, this dumps out the
+# number of callbacks for the most heavily used flavor.
+#
+# Usage: sudo drgn rcu-cbs.py
+#
+# Copyright (C) 2021 Facebook, Inc.
+#
+# Authors: Paul E. McKenney <paulmck@kernel.org>
+
+import sys
+import drgn
+from drgn import NULL, Object
+from drgn.helpers.linux import *
+
+def get_rdp0(prog):
+ try:
+ rdp0 = prog.variable('rcu_preempt_data', 'kernel/rcu/tree.c');
+ except LookupError:
+ rdp0 = NULL;
+
+ if rdp0 == NULL:
+ try:
+ rdp0 = prog.variable('rcu_sched_data',
+ 'kernel/rcu/tree.c');
+ except LookupError:
+ rdp0 = NULL;
+
+ if rdp0 == NULL:
+ rdp0 = prog.variable('rcu_data', 'kernel/rcu/tree.c');
+ return rdp0.address_of_();
+
+rdp0 = get_rdp0(prog);
+
+# Sum up RCU callbacks.
+sum = 0;
+for cpu in for_each_possible_cpu(prog):
+ rdp = per_cpu_ptr(rdp0, cpu);
+ len = rdp.cblist.len.value_();
+ # print("CPU " + str(cpu) + " RCU callbacks: " + str(len));
+ sum += len;
+print("Number of RCU callbacks in flight: " + str(sum));