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" 134