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