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SubjectRe: [PATCH] RCU/torture.txt: remove section MODULE PARAMETERS
On Fri, Jan 4, 2019 at 1:03 AM Paul E. McKenney <paulmck@linux.ibm.com> wrote:
>
> On Thu, Jan 03, 2019 at 10:24:51PM +0800, Junchang Wang wrote:
> > 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>
>
> Queued and pushed, thank you!
>
> I made some small updates, first capitalizing the word following the
> colon (":") in the subject line and second adding a search string
> for Documentation/admin-guide/kernel-parameters.txt. Please see below
> and please let me know if I messed anything up.
>

Hi Paul,

Your updated version is definitely much better. Thanks a lot for
helping review the patch.


--Junchang

> Thanx, Paul
>
> ------------------------------------------------------------------------
>
> commit 150c2476dd32126505dc26f644fa8eb643630d9c
> Author: Junchang Wang <junchangwang@gmail.com>
> Date: Thu Jan 3 22:24:51 2019 +0800
>
> 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. ]
>
> diff --git a/Documentation/RCU/torture.txt b/Documentation/RCU/torture.txt
> index 55918b54808b..a41a0384d20c 100644
> --- a/Documentation/RCU/torture.txt
> +++ b/Documentation/RCU/torture.txt
> @@ -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
>
>

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