linux/kernel/rcu/Kconfig.debug

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# 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
select SRCU
select TASKS_RCU
select TASKS_RUDE_RCU
select TASKS_TRACE_RCU
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
select SRCU
select TASKS_RCU
select TASKS_RUDE_RCU
select TASKS_TRACE_RCU
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)"
refperf: Add a test to measure performance of read-side synchronization Add a test for comparing the performance of RCU with various read-side synchronization mechanisms. The test has proved useful for collecting data and performing these comparisons. Currently RCU, SRCU, reader-writer lock, reader-writer semaphore and reference counting can be measured using refperf.perf_type parameter. Each invocation of the test runs measures performance of a specific mechanism. The maximum number of CPUs to concurrently run readers on is chosen by the test itself and is 75% of the total number of CPUs. So if you had 24 CPUs, the test runs with a maximum of 18 parallel readers. A number of experiments are conducted, and in each experiment, the number of readers is increased by 1, upto the 75% of CPUs mark. During each experiment, all readers execute an empty loop with refperf.loops iterations and time the total loop duration. This is then averaged. Example output: Parameters "refperf.perf_type=srcu refperf.loops=2000000" looks like: [ 3.347133] srcu-ref-perf: [ 3.347133] Threads Time(ns) [ 3.347133] 1 36 [ 3.347133] 2 34 [ 3.347133] 3 34 [ 3.347133] 4 34 [ 3.347133] 5 33 [ 3.347133] 6 33 [ 3.347133] 7 33 [ 3.347133] 8 33 [ 3.347133] 9 33 [ 3.347133] 10 33 [ 3.347133] 11 33 [ 3.347133] 12 33 [ 3.347133] 13 33 [ 3.347133] 14 33 [ 3.347133] 15 32 [ 3.347133] 16 33 [ 3.347133] 17 33 [ 3.347133] 18 34 Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-05-25 04:36:48 +00:00
depends on DEBUG_KERNEL
select TORTURE_TEST
select SRCU
select TASKS_RCU
select TASKS_RUDE_RCU
select TASKS_TRACE_RCU
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_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
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"