1 # SPDX-License-Identifier: GPL-2.0-only 1 # SPDX-License-Identifier: GPL-2.0-only
2 # 2 #
3 # RCU-related debugging configuration options 3 # RCU-related debugging configuration options
4 # 4 #
5 5
6 menu "RCU Debugging" 6 menu "RCU Debugging"
7 7
8 config PROVE_RCU 8 config PROVE_RCU
9 def_bool PROVE_LOCKING 9 def_bool PROVE_LOCKING
10 10
11 config PROVE_RCU_LIST 11 config PROVE_RCU_LIST
12 bool "RCU list lockdep debugging" 12 bool "RCU list lockdep debugging"
13 depends on PROVE_RCU && RCU_EXPERT 13 depends on PROVE_RCU && RCU_EXPERT
14 default n 14 default n
15 help 15 help
16 Enable RCU lockdep checking for list 16 Enable RCU lockdep checking for list usages. By default it is
17 turned off since there are several l 17 turned off since there are several list RCU users that still
18 need to be converted to pass a lockd 18 need to be converted to pass a lockdep expression. To prevent
19 false-positive splats, we keep it de 19 false-positive splats, we keep it default disabled but once all
20 users are converted, we can remove t 20 users are converted, we can remove this config option.
21 21
22 config TORTURE_TEST 22 config TORTURE_TEST
23 tristate 23 tristate
24 default n 24 default n
25 25
26 config RCU_SCALE_TEST 26 config RCU_SCALE_TEST
27 tristate "performance tests for RCU" 27 tristate "performance tests for RCU"
28 depends on DEBUG_KERNEL 28 depends on DEBUG_KERNEL
29 select TORTURE_TEST 29 select TORTURE_TEST
>> 30 select SRCU
>> 31 select TASKS_RCU
>> 32 select TASKS_RUDE_RCU
>> 33 select TASKS_TRACE_RCU
30 default n 34 default n
31 help 35 help
32 This option provides a kernel module 36 This option provides a kernel module that runs performance
33 tests on the RCU infrastructure. Th 37 tests on the RCU infrastructure. The kernel module may be built
34 after the fact on the running kernel 38 after the fact on the running kernel to be tested, if desired.
35 39
36 Say Y here if you want RCU performan 40 Say Y here if you want RCU performance tests to be built into
37 the kernel. 41 the kernel.
38 Say M if you want the RCU performanc 42 Say M if you want the RCU performance tests to build as a module.
39 Say N if you are unsure. 43 Say N if you are unsure.
40 44
41 config RCU_TORTURE_TEST 45 config RCU_TORTURE_TEST
42 tristate "torture tests for RCU" 46 tristate "torture tests for RCU"
43 depends on DEBUG_KERNEL 47 depends on DEBUG_KERNEL
44 select TORTURE_TEST 48 select TORTURE_TEST
>> 49 select SRCU
>> 50 select TASKS_RCU
>> 51 select TASKS_RUDE_RCU
>> 52 select TASKS_TRACE_RCU
45 default n 53 default n
46 help 54 help
47 This option provides a kernel module 55 This option provides a kernel module that runs torture tests
48 on the RCU infrastructure. The kern 56 on the RCU infrastructure. The kernel module may be built
49 after the fact on the running kernel 57 after the fact on the running kernel to be tested, if desired.
50 58
51 Say Y here if you want RCU torture t 59 Say Y here if you want RCU torture tests to be built into
52 the kernel. 60 the kernel.
53 Say M if you want the RCU torture te 61 Say M if you want the RCU torture tests to build as a module.
54 Say N if you are unsure. 62 Say N if you are unsure.
55 63
56 config RCU_REF_SCALE_TEST 64 config RCU_REF_SCALE_TEST
57 tristate "Scalability tests for read-s 65 tristate "Scalability tests for read-side synchronization (RCU and others)"
58 depends on DEBUG_KERNEL 66 depends on DEBUG_KERNEL
59 select TORTURE_TEST 67 select TORTURE_TEST
>> 68 select SRCU
>> 69 select TASKS_RCU
>> 70 select TASKS_RUDE_RCU
>> 71 select TASKS_TRACE_RCU
60 default n 72 default n
61 help 73 help
62 This option provides a kernel module 74 This option provides a kernel module that runs performance tests
63 useful comparing RCU with various re 75 useful comparing RCU with various read-side synchronization mechanisms.
64 The kernel module may be built after 76 The kernel module may be built after the fact on the running kernel to be
65 tested, if desired. 77 tested, if desired.
66 78
67 Say Y here if you want these perform 79 Say Y here if you want these performance tests built into the kernel.
68 Say M if you want to build it as a m 80 Say M if you want to build it as a module instead.
69 Say N if you are unsure. 81 Say N if you are unsure.
70 82
71 config RCU_CPU_STALL_TIMEOUT 83 config RCU_CPU_STALL_TIMEOUT
72 int "RCU CPU stall timeout in seconds" 84 int "RCU CPU stall timeout in seconds"
73 depends on RCU_STALL_COMMON 85 depends on RCU_STALL_COMMON
74 range 3 300 86 range 3 300
75 default 21 87 default 21
76 help 88 help
77 If a given RCU grace period extends 89 If a given RCU grace period extends more than the specified
78 number of seconds, a CPU stall warni 90 number of seconds, a CPU stall warning is printed. If the
79 RCU grace period persists, additiona 91 RCU grace period persists, additional CPU stall warnings are
80 printed at more widely spaced interv 92 printed at more widely spaced intervals.
81 93
82 config RCU_EXP_CPU_STALL_TIMEOUT <<
83 int "Expedited RCU CPU stall timeout i <<
84 depends on RCU_STALL_COMMON <<
85 range 0 300000 <<
86 default 0 <<
87 help <<
88 If a given expedited RCU grace perio <<
89 specified number of milliseconds, a <<
90 If the RCU grace period persists, ad <<
91 are printed at more widely spaced in <<
92 says to use the RCU_CPU_STALL_TIMEOU <<
93 seconds to milliseconds. <<
94 <<
95 config RCU_CPU_STALL_CPUTIME <<
96 bool "Provide additional RCU stall deb <<
97 depends on RCU_STALL_COMMON <<
98 default n <<
99 help <<
100 Collect statistics during the sampli <<
101 (hard interrupts, soft interrupts, t <<
102 (hard interrupts, soft interrupts, k <<
103 RCU stall report. For multiple conti <<
104 periods begin at half of the first R <<
105 The boot option rcupdate.rcu_cpu_sta <<
106 as this one, but will override this <<
107 <<
108 config RCU_CPU_STALL_NOTIFIER <<
109 bool "Provide RCU CPU-stall notifiers" <<
110 depends on RCU_STALL_COMMON <<
111 depends on DEBUG_KERNEL <<
112 depends on RCU_EXPERT <<
113 default n <<
114 help <<
115 WARNING: You almost certainly do no <<
116 <<
117 Enable RCU CPU-stall notifiers, whic <<
118 printing the RCU CPU stall warning. <<
119 callbacks can prevent stall warnings <<
120 And the whole reason that a stall wa <<
121 that something is hung up somewhere. <<
122 callbacks must be written extremely <<
123 containing only lockless code. Afte <<
124 that the whole reason that the RCU C <<
125 the first place is that someone forg <<
126 that you are thinking of acquiring. <<
127 notifier callback acquire that lock <<
128 RCU CPU stall warning from appearing <<
129 <<
130 Say Y here if you want RCU CPU stall <<
131 Say N if you are unsure. <<
132 <<
133 config RCU_TRACE 94 config RCU_TRACE
134 bool "Enable tracing for RCU" 95 bool "Enable tracing for RCU"
135 depends on DEBUG_KERNEL 96 depends on DEBUG_KERNEL
136 default y if TREE_RCU 97 default y if TREE_RCU
137 select TRACE_CLOCK 98 select TRACE_CLOCK
138 help 99 help
139 This option enables additional trace 100 This option enables additional tracepoints for ftrace-style
140 event tracing. 101 event tracing.
141 102
142 Say Y here if you want to enable RCU 103 Say Y here if you want to enable RCU tracing
143 Say N if you are unsure. 104 Say N if you are unsure.
144 105
145 config RCU_EQS_DEBUG 106 config RCU_EQS_DEBUG
146 bool "Provide debugging asserts for ad 107 bool "Provide debugging asserts for adding NO_HZ support to an arch"
147 depends on DEBUG_KERNEL 108 depends on DEBUG_KERNEL
148 help 109 help
149 This option provides consistency che 110 This option provides consistency checks in RCU's handling of
150 NO_HZ. These checks have proven qui 111 NO_HZ. These checks have proven quite helpful in detecting
151 bugs in arch-specific NO_HZ code. 112 bugs in arch-specific NO_HZ code.
152 113
153 Say N here if you need ultimate kern 114 Say N here if you need ultimate kernel/user switch latencies
154 Say Y if you are unsure 115 Say Y if you are unsure
155 116
156 config RCU_STRICT_GRACE_PERIOD 117 config RCU_STRICT_GRACE_PERIOD
157 bool "Provide debug RCU implementation 118 bool "Provide debug RCU implementation with short grace periods"
158 depends on DEBUG_KERNEL && RCU_EXPERT !! 119 depends on DEBUG_KERNEL && RCU_EXPERT
159 default n 120 default n
160 select PREEMPT_COUNT if PREEMPT=n 121 select PREEMPT_COUNT if PREEMPT=n
161 help 122 help
162 Select this option to build an RCU v 123 Select this option to build an RCU variant that is strict about
163 grace periods, making them as short 124 grace periods, making them as short as it can. This limits
164 scalability, destroys real-time resp 125 scalability, destroys real-time response, degrades battery
165 lifetime and kills performance. Don 126 lifetime and kills performance. Don't try this on large
166 machines, as in systems with more th 127 machines, as in systems with more than about 10 or 20 CPUs.
167 But in conjunction with tools like K 128 But in conjunction with tools like KASAN, it can be helpful
168 when looking for certain types of RC 129 when looking for certain types of RCU usage bugs, for example,
169 too-short RCU read-side critical sec 130 too-short RCU read-side critical sections.
170 131
171 endmenu # "RCU Debugging" 132 endmenu # "RCU Debugging"
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.