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authorJunchang Wang <junchangwang@gmail.com>2019-01-03 09:24:51 -0500
committerPaul E. McKenney <paulmck@linux.ibm.com>2019-01-25 18:37:14 -0500
commit6684880a8b161994e320d8cad70d9ea5dc87f031 (patch)
treecb2ff998aba14458d36632773463c6602fc6c102
parent6f7541df3a6cbf530da0ec19d402acc1a3de1b30 (diff)
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. ]
-rw-r--r--Documentation/RCU/torture.txt169
1 files changed, 2 insertions, 167 deletions
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
10command (perhaps grepping for "torture"). The test is started 10command (perhaps grepping for "torture"). The test is started
11when the module is loaded, and stops when the module is unloaded. 11when the module is loaded, and stops when the module is unloaded.
12 12
13 13Module parameters are prefixed by "rcutorture." in
14MODULE PARAMETERS 14Documentation/admin-guide/kernel-parameters.txt.
15
16This module has the following parameters:
17
18fqs_duration Duration (in microseconds) of artificially induced bursts
19 of force_quiescent_state() invocations. In RCU
20 implementations having force_quiescent_state(), these
21 bursts help force races between forcing a given grace
22 period and that grace period ending on its own.
23
24fqs_holdoff Holdoff time (in microseconds) between consecutive calls
25 to force_quiescent_state() within a burst.
26
27fqs_stutter Wait time (in seconds) between consecutive bursts
28 of calls to force_quiescent_state().
29
30gp_normal Make the fake writers use normal synchronous grace-period
31 primitives.
32
33gp_exp Make the fake writers use expedited synchronous grace-period
34 primitives. If both gp_normal and gp_exp are set, or
35 if neither gp_normal nor gp_exp are set, then randomly
36 choose the primitive so that about 50% are normal and
37 50% expedited. By default, neither are set, which
38 gives best overall test coverage.
39
40irqreader Says to invoke RCU readers from irq level. This is currently
41 done via timers. Defaults to "1" for variants of RCU that
42 permit this. (Or, more accurately, variants of RCU that do
43 -not- permit this know to ignore this variable.)
44
45n_barrier_cbs If this is nonzero, RCU barrier testing will be conducted,
46 in which case n_barrier_cbs specifies the number of
47 RCU callbacks (and corresponding kthreads) to use for
48 this testing. The value cannot be negative. If you
49 specify this to be non-zero when torture_type indicates a
50 synchronous RCU implementation (one for which a member of
51 the synchronize_rcu() rather than the call_rcu() family is
52 used -- see the documentation for torture_type below), an
53 error will be reported and no testing will be carried out.
54
55nfakewriters This is the number of RCU fake writer threads to run. Fake
56 writer threads repeatedly use the synchronous "wait for
57 current readers" function of the interface selected by
58 torture_type, with a delay between calls to allow for various
59 different numbers of writers running in parallel.
60 nfakewriters defaults to 4, which provides enough parallelism
61 to trigger special cases caused by multiple writers, such as
62 the synchronize_srcu() early return optimization.
63
64nreaders This is the number of RCU reading threads supported.
65 The default is twice the number of CPUs. Why twice?
66 To properly exercise RCU implementations with preemptible
67 read-side critical sections.
68
69onoff_interval
70 The number of seconds between each attempt to execute a
71 randomly selected CPU-hotplug operation. Defaults to
72 zero, which disables CPU hotplugging. In HOTPLUG_CPU=n
73 kernels, rcutorture will silently refuse to do any
74 CPU-hotplug operations regardless of what value is
75 specified for onoff_interval.
76
77onoff_holdoff The number of seconds to wait until starting CPU-hotplug
78 operations. This would normally only be used when
79 rcutorture was built into the kernel and started
80 automatically at boot time, in which case it is useful
81 in order to avoid confusing boot-time code with CPUs
82 coming and going.
83
84shuffle_interval
85 The number of seconds to keep the test threads affinitied
86 to a particular subset of the CPUs, defaults to 3 seconds.
87 Used in conjunction with test_no_idle_hz.
88
89shutdown_secs The number of seconds to run the test before terminating
90 the test and powering off the system. The default is
91 zero, which disables test termination and system shutdown.
92 This capability is useful for automated testing.
93
94stall_cpu The number of seconds that a CPU should be stalled while
95 within both an rcu_read_lock() and a preempt_disable().
96 This stall happens only once per rcutorture run.
97 If you need multiple stalls, use modprobe and rmmod to
98 repeatedly run rcutorture. The default for stall_cpu
99 is zero, which prevents rcutorture from stalling a CPU.
100
101 Note that attempts to rmmod rcutorture while the stall
102 is ongoing will hang, so be careful what value you
103 choose for this module parameter! In addition, too-large
104 values for stall_cpu might well induce failures and
105 warnings in other parts of the kernel. You have been
106 warned!
107
108stall_cpu_holdoff
109 The number of seconds to wait after rcutorture starts
110 before stalling a CPU. Defaults to 10 seconds.
111
112stat_interval The number of seconds between output of torture
113 statistics (via printk()). Regardless of the interval,
114 statistics are printed when the module is unloaded.
115 Setting the interval to zero causes the statistics to
116 be printed -only- when the module is unloaded, and this
117 is the default.
118
119stutter The length of time to run the test before pausing for this
120 same period of time. Defaults to "stutter=5", so as
121 to run and pause for (roughly) five-second intervals.
122 Specifying "stutter=0" causes the test to run continuously
123 without pausing, which is the old default behavior.
124
125test_boost Whether or not to test the ability of RCU to do priority
126 boosting. Defaults to "test_boost=1", which performs
127 RCU priority-inversion testing only if the selected
128 RCU implementation supports priority boosting. Specifying
129 "test_boost=0" never performs RCU priority-inversion
130 testing. Specifying "test_boost=2" performs RCU
131 priority-inversion testing even if the selected RCU
132 implementation does not support RCU priority boosting,
133 which can be used to test rcutorture's ability to
134 carry out RCU priority-inversion testing.
135
136test_boost_interval
137 The number of seconds in an RCU priority-inversion test
138 cycle. Defaults to "test_boost_interval=7". It is
139 usually wise for this value to be relatively prime to
140 the value selected for "stutter".
141
142test_boost_duration
143 The number of seconds to do RCU priority-inversion testing
144 within any given "test_boost_interval". Defaults to
145 "test_boost_duration=4".
146
147test_no_idle_hz Whether or not to test the ability of RCU to operate in
148 a kernel that disables the scheduling-clock interrupt to
149 idle CPUs. Boolean parameter, "1" to test, "0" otherwise.
150 Defaults to omitting this test.
151
152torture_type The type of RCU to test, with string values as follows:
153
154 "rcu": rcu_read_lock(), rcu_read_unlock() and call_rcu(),
155 along with expedited, synchronous, and polling
156 variants.
157
158 "rcu_bh": rcu_read_lock_bh(), rcu_read_unlock_bh(), and
159 call_rcu_bh(), along with expedited and synchronous
160 variants.
161
162 "rcu_busted": This tests an intentionally incorrect version
163 of RCU in order to help test rcutorture itself.
164
165 "srcu": srcu_read_lock(), srcu_read_unlock() and
166 call_srcu(), along with expedited and
167 synchronous variants.
168
169 "sched": preempt_disable(), preempt_enable(), and
170 call_rcu_sched(), along with expedited,
171 synchronous, and polling variants.
172
173 "tasks": voluntary context switch and call_rcu_tasks(),
174 along with expedited and synchronous variants.
175
176 Defaults to "rcu".
177
178verbose Enable debug printk()s. Default is disabled.
179
180 15
181OUTPUT 16OUTPUT
182 17