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RCU/torture.txt: Remove section MODULE PARAMETERS

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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. ]
This commit is contained in:
Junchang Wang 2019-01-03 22:24:51 +08:00 committed by Paul E. McKenney
parent 6f7541df3a
commit 6684880a8b
1 changed files with 2 additions and 167 deletions
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169
Documentation/RCU/torture.txt
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@ -10,173 +10,8 @@ status messages via printk(), which can be examined via the dmesg
command (perhaps grepping for "torture"). The test is started
when the module is loaded, and stops when the module is unloaded.
MODULE PARAMETERS
This module has the following parameters:
fqs_duration Duration (in microseconds) of artificially induced bursts
of force_quiescent_state() invocations. In RCU
implementations having force_quiescent_state(), these
bursts help force races between forcing a given grace
period and that grace period ending on its own.
fqs_holdoff Holdoff time (in microseconds) between consecutive calls
to force_quiescent_state() within a burst.
fqs_stutter Wait time (in seconds) between consecutive bursts
of calls to force_quiescent_state().
gp_normal Make the fake writers use normal synchronous grace-period
primitives.
gp_exp Make the fake writers use expedited synchronous grace-period
primitives. If both gp_normal and gp_exp are set, or
if neither gp_normal nor gp_exp are set, then randomly
choose the primitive so that about 50% are normal and
50% expedited. By default, neither are set, which
gives best overall test coverage.
irqreader Says to invoke RCU readers from irq level. This is currently
done via timers. Defaults to "1" for variants of RCU that
permit this. (Or, more accurately, variants of RCU that do
-not- permit this know to ignore this variable.)
n_barrier_cbs If this is nonzero, RCU barrier testing will be conducted,
in which case n_barrier_cbs specifies the number of
RCU callbacks (and corresponding kthreads) to use for
this testing. The value cannot be negative. If you
specify this to be non-zero when torture_type indicates a
synchronous RCU implementation (one for which a member of
the synchronize_rcu() rather than the call_rcu() family is
used -- see the documentation for torture_type below), an
error will be reported and no testing will be carried out.
nfakewriters This is the number of RCU fake writer threads to run. Fake
writer threads repeatedly use the synchronous "wait for
current readers" function of the interface selected by
torture_type, with a delay between calls to allow for various
different numbers of writers running in parallel.
nfakewriters defaults to 4, which provides enough parallelism
to trigger special cases caused by multiple writers, such as
the synchronize_srcu() early return optimization.
nreaders This is the number of RCU reading threads supported.
The default is twice the number of CPUs. Why twice?
To properly exercise RCU implementations with preemptible
read-side critical sections.
onoff_interval
The number of seconds between each attempt to execute a
randomly selected CPU-hotplug operation. Defaults to
zero, which disables CPU hotplugging. In HOTPLUG_CPU=n
kernels, rcutorture will silently refuse to do any
CPU-hotplug operations regardless of what value is
specified for onoff_interval.
onoff_holdoff The number of seconds to wait until starting CPU-hotplug
operations. This would normally only be used when
rcutorture was built into the kernel and started
automatically at boot time, in which case it is useful
in order to avoid confusing boot-time code with CPUs
coming and going.
shuffle_interval
The number of seconds to keep the test threads affinitied
to a particular subset of the CPUs, defaults to 3 seconds.
Used in conjunction with test_no_idle_hz.
shutdown_secs The number of seconds to run the test before terminating
the test and powering off the system. The default is
zero, which disables test termination and system shutdown.
This capability is useful for automated testing.
stall_cpu The number of seconds that a CPU should be stalled while
within both an rcu_read_lock() and a preempt_disable().
This stall happens only once per rcutorture run.
If you need multiple stalls, use modprobe and rmmod to
repeatedly run rcutorture. The default for stall_cpu
is zero, which prevents rcutorture from stalling a CPU.
Note that attempts to rmmod rcutorture while the stall
is ongoing will hang, so be careful what value you
choose for this module parameter! In addition, too-large
values for stall_cpu might well induce failures and
warnings in other parts of the kernel. You have been
warned!
stall_cpu_holdoff
The number of seconds to wait after rcutorture starts
before stalling a CPU. Defaults to 10 seconds.
stat_interval The number of seconds between output of torture
statistics (via printk()). Regardless of the interval,
statistics are printed when the module is unloaded.
Setting the interval to zero causes the statistics to
be printed -only- when the module is unloaded, and this
is the default.
stutter The length of time to run the test before pausing for this
same period of time. Defaults to "stutter=5", so as
to run and pause for (roughly) five-second intervals.
Specifying "stutter=0" causes the test to run continuously
without pausing, which is the old default behavior.
test_boost Whether or not to test the ability of RCU to do priority
boosting. Defaults to "test_boost=1", which performs
RCU priority-inversion testing only if the selected
RCU implementation supports priority boosting. Specifying
"test_boost=0" never performs RCU priority-inversion
testing. Specifying "test_boost=2" performs RCU
priority-inversion testing even if the selected RCU
implementation does not support RCU priority boosting,
which can be used to test rcutorture's ability to
carry out RCU priority-inversion testing.
test_boost_interval
The number of seconds in an RCU priority-inversion test
cycle. Defaults to "test_boost_interval=7". It is
usually wise for this value to be relatively prime to
the value selected for "stutter".
test_boost_duration
The number of seconds to do RCU priority-inversion testing
within any given "test_boost_interval". Defaults to
"test_boost_duration=4".
test_no_idle_hz Whether or not to test the ability of RCU to operate in
a kernel that disables the scheduling-clock interrupt to
idle CPUs. Boolean parameter, "1" to test, "0" otherwise.
Defaults to omitting this test.
torture_type The type of RCU to test, with string values as follows:
"rcu": rcu_read_lock(), rcu_read_unlock() and call_rcu(),
along with expedited, synchronous, and polling
variants.
"rcu_bh": rcu_read_lock_bh(), rcu_read_unlock_bh(), and
call_rcu_bh(), along with expedited and synchronous
variants.
"rcu_busted": This tests an intentionally incorrect version
of RCU in order to help test rcutorture itself.
"srcu": srcu_read_lock(), srcu_read_unlock() and
call_srcu(), along with expedited and
synchronous variants.
"sched": preempt_disable(), preempt_enable(), and
call_rcu_sched(), along with expedited,
synchronous, and polling variants.
"tasks": voluntary context switch and call_rcu_tasks(),
along with expedited and synchronous variants.
Defaults to "rcu".
verbose Enable debug printk()s. Default is disabled.
Module parameters are prefixed by "rcutorture." in
Documentation/admin-guide/kernel-parameters.txt.
OUTPUT