1# SPDX-License-Identifier: GPL-2.0-only
2#
3# RCU-related debugging configuration options
4#
5
6menu "RCU Debugging"
7
8config PROVE_RCU
9	def_bool PROVE_LOCKING
10
11config PROVE_RCU_LIST
12	bool "RCU list lockdep debugging"
13	depends on PROVE_RCU && RCU_EXPERT
14	default n
15	help
16	  Enable RCU lockdep checking for list usages. By default it is
17	  turned off since there are several list RCU users that still
18	  need to be converted to pass a lockdep expression. To prevent
19	  false-positive splats, we keep it default disabled but once all
20	  users are converted, we can remove this config option.
21
22config TORTURE_TEST
23	tristate
24	default n
25
26config RCU_SCALE_TEST
27	tristate "performance tests for RCU"
28	depends on DEBUG_KERNEL
29	select TORTURE_TEST
30	select SRCU
31	default n
32	help
33	  This option provides a kernel module that runs performance
34	  tests on the RCU infrastructure.  The kernel module may be built
35	  after the fact on the running kernel to be tested, if desired.
36
37	  Say Y here if you want RCU performance tests to be built into
38	  the kernel.
39	  Say M if you want the RCU performance tests to build as a module.
40	  Say N if you are unsure.
41
42config RCU_TORTURE_TEST
43	tristate "torture tests for RCU"
44	depends on DEBUG_KERNEL
45	select TORTURE_TEST
46	select SRCU
47	default n
48	help
49	  This option provides a kernel module that runs torture tests
50	  on the RCU infrastructure.  The kernel module may be built
51	  after the fact on the running kernel to be tested, if desired.
52
53	  Say Y here if you want RCU torture tests to be built into
54	  the kernel.
55	  Say M if you want the RCU torture tests to build as a module.
56	  Say N if you are unsure.
57
58config RCU_REF_SCALE_TEST
59	tristate "Scalability tests for read-side synchronization (RCU and others)"
60	depends on DEBUG_KERNEL
61	select TORTURE_TEST
62	select SRCU
63	default n
64	help
65	  This option provides a kernel module that runs performance tests
66	  useful comparing RCU with various read-side synchronization mechanisms.
67	  The kernel module may be built after the fact on the running kernel to be
68	  tested, if desired.
69
70	  Say Y here if you want these performance tests built into the kernel.
71	  Say M if you want to build it as a module instead.
72	  Say N if you are unsure.
73
74config RCU_CPU_STALL_TIMEOUT
75	int "RCU CPU stall timeout in seconds"
76	depends on RCU_STALL_COMMON
77	range 3 300
78	default 21
79	help
80	  If a given RCU grace period extends more than the specified
81	  number of seconds, a CPU stall warning is printed.  If the
82	  RCU grace period persists, additional CPU stall warnings are
83	  printed at more widely spaced intervals.
84
85config RCU_EXP_CPU_STALL_TIMEOUT
86	int "Expedited RCU CPU stall timeout in milliseconds"
87	depends on RCU_STALL_COMMON
88	range 0 21000
89	default 0
90	help
91	  If a given expedited RCU grace period extends more than the
92	  specified number of milliseconds, a CPU stall warning is printed.
93	  If the RCU grace period persists, additional CPU stall warnings
94	  are printed at more widely spaced intervals.  A value of zero
95	  says to use the RCU_CPU_STALL_TIMEOUT value converted from
96	  seconds to milliseconds.
97
98config RCU_TRACE
99	bool "Enable tracing for RCU"
100	depends on DEBUG_KERNEL
101	default y if TREE_RCU
102	select TRACE_CLOCK
103	help
104	  This option enables additional tracepoints for ftrace-style
105	  event tracing.
106
107	  Say Y here if you want to enable RCU tracing
108	  Say N if you are unsure.
109
110config RCU_EQS_DEBUG
111	bool "Provide debugging asserts for adding NO_HZ support to an arch"
112	depends on DEBUG_KERNEL
113	help
114	  This option provides consistency checks in RCU's handling of
115	  NO_HZ.  These checks have proven quite helpful in detecting
116	  bugs in arch-specific NO_HZ code.
117
118	  Say N here if you need ultimate kernel/user switch latencies
119	  Say Y if you are unsure
120
121config RCU_STRICT_GRACE_PERIOD
122	bool "Provide debug RCU implementation with short grace periods"
123	depends on DEBUG_KERNEL && RCU_EXPERT && NR_CPUS <= 4 && !TINY_RCU
124	default n
125	select PREEMPT_COUNT if PREEMPT=n
126	help
127	  Select this option to build an RCU variant that is strict about
128	  grace periods, making them as short as it can.  This limits
129	  scalability, destroys real-time response, degrades battery
130	  lifetime and kills performance.  Don't try this on large
131	  machines, as in systems with more than about 10 or 20 CPUs.
132	  But in conjunction with tools like KASAN, it can be helpful
133	  when looking for certain types of RCU usage bugs, for example,
134	  too-short RCU read-side critical sections.
135
136endmenu # "RCU Debugging"
137