RCU/torture.txt: Remove section MODULE PARAMETERS
The supported module parameters are detailed in both RCU/torture.txt and admin-guide/kernel-parameters.txt, and the latter is actively maintained. So this patch removes section MODULE PARAMETERS in torture.txt and adds a reference to the information in kernel-parameters.txt. Signed-off-by: Junchang Wang <junchangwang@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> [ paulmck: Add search string. ]
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Junchang Wang
Paul E. McKenney
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6684880a8b
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@ -10,173 +10,8 @@ status messages via printk(), which can be examined via the dmesg
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command (perhaps grepping for "torture"). The test is started
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when the module is loaded, and stops when the module is unloaded.
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MODULE PARAMETERS
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This module has the following parameters:
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fqs_duration Duration (in microseconds) of artificially induced bursts
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of force_quiescent_state() invocations. In RCU
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implementations having force_quiescent_state(), these
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bursts help force races between forcing a given grace
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period and that grace period ending on its own.
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fqs_holdoff Holdoff time (in microseconds) between consecutive calls
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to force_quiescent_state() within a burst.
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fqs_stutter Wait time (in seconds) between consecutive bursts
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of calls to force_quiescent_state().
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gp_normal Make the fake writers use normal synchronous grace-period
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primitives.
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gp_exp Make the fake writers use expedited synchronous grace-period
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primitives. If both gp_normal and gp_exp are set, or
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if neither gp_normal nor gp_exp are set, then randomly
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choose the primitive so that about 50% are normal and
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50% expedited. By default, neither are set, which
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gives best overall test coverage.
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irqreader Says to invoke RCU readers from irq level. This is currently
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done via timers. Defaults to "1" for variants of RCU that
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permit this. (Or, more accurately, variants of RCU that do
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-not- permit this know to ignore this variable.)
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n_barrier_cbs If this is nonzero, RCU barrier testing will be conducted,
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in which case n_barrier_cbs specifies the number of
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RCU callbacks (and corresponding kthreads) to use for
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this testing. The value cannot be negative. If you
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specify this to be non-zero when torture_type indicates a
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synchronous RCU implementation (one for which a member of
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the synchronize_rcu() rather than the call_rcu() family is
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used -- see the documentation for torture_type below), an
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error will be reported and no testing will be carried out.
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nfakewriters This is the number of RCU fake writer threads to run. Fake
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writer threads repeatedly use the synchronous "wait for
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current readers" function of the interface selected by
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torture_type, with a delay between calls to allow for various
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different numbers of writers running in parallel.
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nfakewriters defaults to 4, which provides enough parallelism
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to trigger special cases caused by multiple writers, such as
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the synchronize_srcu() early return optimization.
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nreaders This is the number of RCU reading threads supported.
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The default is twice the number of CPUs. Why twice?
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To properly exercise RCU implementations with preemptible
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read-side critical sections.
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onoff_interval
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The number of seconds between each attempt to execute a
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randomly selected CPU-hotplug operation. Defaults to
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zero, which disables CPU hotplugging. In HOTPLUG_CPU=n
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kernels, rcutorture will silently refuse to do any
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CPU-hotplug operations regardless of what value is
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specified for onoff_interval.
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onoff_holdoff The number of seconds to wait until starting CPU-hotplug
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operations. This would normally only be used when
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rcutorture was built into the kernel and started
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automatically at boot time, in which case it is useful
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in order to avoid confusing boot-time code with CPUs
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coming and going.
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shuffle_interval
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The number of seconds to keep the test threads affinitied
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to a particular subset of the CPUs, defaults to 3 seconds.
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Used in conjunction with test_no_idle_hz.
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shutdown_secs The number of seconds to run the test before terminating
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the test and powering off the system. The default is
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zero, which disables test termination and system shutdown.
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This capability is useful for automated testing.
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stall_cpu The number of seconds that a CPU should be stalled while
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within both an rcu_read_lock() and a preempt_disable().
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This stall happens only once per rcutorture run.
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If you need multiple stalls, use modprobe and rmmod to
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repeatedly run rcutorture. The default for stall_cpu
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is zero, which prevents rcutorture from stalling a CPU.
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Note that attempts to rmmod rcutorture while the stall
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is ongoing will hang, so be careful what value you
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choose for this module parameter! In addition, too-large
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values for stall_cpu might well induce failures and
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warnings in other parts of the kernel. You have been
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warned!
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stall_cpu_holdoff
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The number of seconds to wait after rcutorture starts
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before stalling a CPU. Defaults to 10 seconds.
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stat_interval The number of seconds between output of torture
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statistics (via printk()). Regardless of the interval,
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statistics are printed when the module is unloaded.
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Setting the interval to zero causes the statistics to
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be printed -only- when the module is unloaded, and this
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is the default.
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stutter The length of time to run the test before pausing for this
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same period of time. Defaults to "stutter=5", so as
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to run and pause for (roughly) five-second intervals.
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Specifying "stutter=0" causes the test to run continuously
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without pausing, which is the old default behavior.
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test_boost Whether or not to test the ability of RCU to do priority
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boosting. Defaults to "test_boost=1", which performs
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RCU priority-inversion testing only if the selected
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RCU implementation supports priority boosting. Specifying
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"test_boost=0" never performs RCU priority-inversion
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testing. Specifying "test_boost=2" performs RCU
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priority-inversion testing even if the selected RCU
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implementation does not support RCU priority boosting,
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which can be used to test rcutorture's ability to
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carry out RCU priority-inversion testing.
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test_boost_interval
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The number of seconds in an RCU priority-inversion test
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cycle. Defaults to "test_boost_interval=7". It is
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usually wise for this value to be relatively prime to
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the value selected for "stutter".
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test_boost_duration
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The number of seconds to do RCU priority-inversion testing
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within any given "test_boost_interval". Defaults to
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"test_boost_duration=4".
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test_no_idle_hz Whether or not to test the ability of RCU to operate in
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a kernel that disables the scheduling-clock interrupt to
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idle CPUs. Boolean parameter, "1" to test, "0" otherwise.
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Defaults to omitting this test.
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torture_type The type of RCU to test, with string values as follows:
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"rcu": rcu_read_lock(), rcu_read_unlock() and call_rcu(),
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along with expedited, synchronous, and polling
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variants.
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"rcu_bh": rcu_read_lock_bh(), rcu_read_unlock_bh(), and
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call_rcu_bh(), along with expedited and synchronous
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variants.
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"rcu_busted": This tests an intentionally incorrect version
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of RCU in order to help test rcutorture itself.
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"srcu": srcu_read_lock(), srcu_read_unlock() and
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call_srcu(), along with expedited and
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synchronous variants.
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"sched": preempt_disable(), preempt_enable(), and
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call_rcu_sched(), along with expedited,
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synchronous, and polling variants.
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"tasks": voluntary context switch and call_rcu_tasks(),
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along with expedited and synchronous variants.
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Defaults to "rcu".
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verbose Enable debug printk()s. Default is disabled.
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Module parameters are prefixed by "rcutorture." in
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Documentation/admin-guide/kernel-parameters.txt.
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OUTPUT
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