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