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653ed64b01
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>
118 lines
3.4 KiB
Plaintext
118 lines
3.4 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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#
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# RCU-related debugging configuration options
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#
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menu "RCU Debugging"
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config PROVE_RCU
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def_bool PROVE_LOCKING
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config PROVE_RCU_LIST
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bool "RCU list lockdep debugging"
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depends on PROVE_RCU && RCU_EXPERT
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default n
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help
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Enable RCU lockdep checking for list usages. By default it is
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turned off since there are several list RCU users that still
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need to be converted to pass a lockdep expression. To prevent
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false-positive splats, we keep it default disabled but once all
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users are converted, we can remove this config option.
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config TORTURE_TEST
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tristate
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default n
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config RCU_PERF_TEST
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tristate "performance tests for RCU"
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depends on DEBUG_KERNEL
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select TORTURE_TEST
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select SRCU
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select TASKS_RCU
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select TASKS_RUDE_RCU
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select TASKS_TRACE_RCU
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default n
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help
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This option provides a kernel module that runs performance
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tests on the RCU infrastructure. The kernel module may be built
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after the fact on the running kernel to be tested, if desired.
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Say Y here if you want RCU performance tests to be built into
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the kernel.
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Say M if you want the RCU performance tests to build as a module.
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Say N if you are unsure.
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config RCU_TORTURE_TEST
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tristate "torture tests for RCU"
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depends on DEBUG_KERNEL
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select TORTURE_TEST
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select SRCU
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select TASKS_RCU
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select TASKS_RUDE_RCU
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select TASKS_TRACE_RCU
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default n
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help
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This option provides a kernel module that runs torture tests
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on the RCU infrastructure. The kernel module may be built
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after the fact on the running kernel to be tested, if desired.
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Say Y here if you want RCU torture tests to be built into
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the kernel.
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Say M if you want the RCU torture tests to build as a module.
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Say N if you are unsure.
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config RCU_REF_PERF_TEST
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tristate "Performance tests for read-side synchronization (RCU and others)"
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depends on DEBUG_KERNEL
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select TORTURE_TEST
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select SRCU
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select TASKS_RCU
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select TASKS_RUDE_RCU
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select TASKS_TRACE_RCU
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default n
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help
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This option provides a kernel module that runs performance tests
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useful comparing RCU with various read-side synchronization mechanisms.
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The kernel module may be built after the fact on the running kernel to be
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tested, if desired.
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Say Y here if you want these performance tests built into the kernel.
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Say M if you want to build it as a module instead.
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Say N if you are unsure.
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config RCU_CPU_STALL_TIMEOUT
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int "RCU CPU stall timeout in seconds"
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depends on RCU_STALL_COMMON
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range 3 300
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default 21
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help
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If a given RCU grace period extends more than the specified
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number of seconds, a CPU stall warning is printed. If the
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RCU grace period persists, additional CPU stall warnings are
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printed at more widely spaced intervals.
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config RCU_TRACE
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bool "Enable tracing for RCU"
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depends on DEBUG_KERNEL
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default y if TREE_RCU
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select TRACE_CLOCK
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help
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This option enables additional tracepoints for ftrace-style
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event tracing.
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Say Y here if you want to enable RCU tracing
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Say N if you are unsure.
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config RCU_EQS_DEBUG
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bool "Provide debugging asserts for adding NO_HZ support to an arch"
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depends on DEBUG_KERNEL
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help
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This option provides consistency checks in RCU's handling of
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NO_HZ. These checks have proven quite helpful in detecting
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bugs in arch-specific NO_HZ code.
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Say N here if you need ultimate kernel/user switch latencies
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Say Y if you are unsure
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endmenu # "RCU Debugging"
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