# SPDX-License-Identifier: GPL-2.0-only # # RCU-related debugging configuration options # menu "RCU Debugging" config PROVE_RCU def_bool PROVE_LOCKING config PROVE_RCU_LIST bool "RCU list lockdep debugging" depends on PROVE_RCU && RCU_EXPERT default n help Enable RCU lockdep checking for list usages. By default it is turned off since there are several list RCU users that still need to be converted to pass a lockdep expression. To prevent false-positive splats, we keep it default disabled but once all users are converted, we can remove this config option. config TORTURE_TEST tristate default n config RCU_SCALE_TEST tristate "performance tests for RCU" depends on DEBUG_KERNEL select TORTURE_TEST default n help This option provides a kernel module that runs performance tests on the RCU infrastructure. The kernel module may be built after the fact on the running kernel to be tested, if desired. Say Y here if you want RCU performance tests to be built into the kernel. Say M if you want the RCU performance tests to build as a module. Say N if you are unsure. config RCU_TORTURE_TEST tristate "torture tests for RCU" depends on DEBUG_KERNEL select TORTURE_TEST default n help This option provides a kernel module that runs torture tests on the RCU infrastructure. The kernel module may be built after the fact on the running kernel to be tested, if desired. Say Y here if you want RCU torture tests to be built into the kernel. Say M if you want the RCU torture tests to build as a module. Say N if you are unsure. config RCU_REF_SCALE_TEST tristate "Scalability tests for read-side synchronization (RCU and others)" depends on DEBUG_KERNEL select TORTURE_TEST default n help This option provides a kernel module that runs performance tests useful comparing RCU with various read-side synchronization mechanisms. The kernel module may be built after the fact on the running kernel to be tested, if desired. Say Y here if you want these performance tests built into the kernel. Say M if you want to build it as a module instead. Say N if you are unsure. config RCU_CPU_STALL_TIMEOUT int "RCU CPU stall timeout in seconds" depends on RCU_STALL_COMMON range 3 300 default 21 help If a given RCU grace period extends more than the specified number of seconds, a CPU stall warning is printed. If the RCU grace period persists, additional CPU stall warnings are printed at more widely spaced intervals. config RCU_EXP_CPU_STALL_TIMEOUT int "Expedited RCU CPU stall timeout in milliseconds" depends on RCU_STALL_COMMON range 0 300000 default 0 help If a given expedited RCU grace period extends more than the specified number of milliseconds, a CPU stall warning is printed. If the RCU grace period persists, additional CPU stall warnings are printed at more widely spaced intervals. A value of zero says to use the RCU_CPU_STALL_TIMEOUT value converted from seconds to milliseconds. config RCU_CPU_STALL_CPUTIME bool "Provide additional RCU stall debug information" depends on RCU_STALL_COMMON default n help Collect statistics during the sampling period, such as the number of (hard interrupts, soft interrupts, task switches) and the cputime of (hard interrupts, soft interrupts, kernel tasks) are added to the RCU stall report. For multiple continuous RCU stalls, all sampling periods begin at half of the first RCU stall timeout. The boot option rcupdate.rcu_cpu_stall_cputime has the same function as this one, but will override this if it exists. config RCU_TRACE bool "Enable tracing for RCU" depends on DEBUG_KERNEL default y if TREE_RCU select TRACE_CLOCK help This option enables additional tracepoints for ftrace-style event tracing. Say Y here if you want to enable RCU tracing Say N if you are unsure. config RCU_EQS_DEBUG bool "Provide debugging asserts for adding NO_HZ support to an arch" depends on DEBUG_KERNEL help This option provides consistency checks in RCU's handling of NO_HZ. These checks have proven quite helpful in detecting bugs in arch-specific NO_HZ code. Say N here if you need ultimate kernel/user switch latencies Say Y if you are unsure config RCU_STRICT_GRACE_PERIOD bool "Provide debug RCU implementation with short grace periods" depends on DEBUG_KERNEL && RCU_EXPERT && NR_CPUS <= 4 && !TINY_RCU default n select PREEMPT_COUNT if PREEMPT=n help Select this option to build an RCU variant that is strict about grace periods, making them as short as it can. This limits scalability, destroys real-time response, degrades battery lifetime and kills performance. Don't try this on large machines, as in systems with more than about 10 or 20 CPUs. But in conjunction with tools like KASAN, it can be helpful when looking for certain types of RCU usage bugs, for example, too-short RCU read-side critical sections. endmenu # "RCU Debugging"