Documentation/RCU/torture.rst

1 .. SPDX-License-Identifier: GPL-2.0
19 Documentation/admin-guide/kernel-parameters.txt.
26 …rcu-torture:--- Start of test: nreaders=16 nfakewriters=4 stat_interval=30 verbose=0 test_no_idle_…
27 …rcu-torture: rtc:           (null) ver: 155441 tfle: 0 rta: 155441 rtaf: 8884 rtf: 155440 rtmbe: 0…
28 	rcu-torture: Reader Pipe:  727860534 34213 0 0 0 0 0 0 0 0 0
29 	rcu-torture: Reader Batch:  727877838 17003 0 0 0 0 0 0 0 0 0
30 …rcu-torture: Free-Block Circulation:  155440 155440 155440 155440 155440 155440 155440 155440 1554…
31 …rcu-torture:--- End of test: SUCCESS: nreaders=16 nfakewriters=4 stat_interval=30 verbose=0 test_n…
37 be evident.  ;-)
51 *	"tfle": If non-zero, indicates that the "torture freelist"
54 	that RCU is working when it is not.  :-/
60 	to be non-zero, but it is bad for it to be a large fraction of
65 *	"rtmbe": A non-zero value indicates that rcutorture believes that
67 	correctly.  This value should be zero.
69 *	"rtbe": A non-zero value indicates that one of the rcu_barrier()
72 *	"rtbke": rcutorture was unable to create the real-time kthreads
73 	used to force RCU priority inversion.  This value should be zero.
77 	to the real-time priority level of 1.  This value should be zero.
85 	value should be non-zero.
87 *	"nt": The number of times rcutorture ran RCU read-side code from
88 	within a timer handler.  This value should be non-zero only
92 	If any entries past the first two are non-zero, RCU is broken.
94 	you notice.  The age of a newly allocated structure is zero,
96 	incremented once per grace period subsequently -- and is freed
97 	after passing through (RCU_TORTURE_PIPE_LEN-2) grace periods.
101 	it yourself.  ;-)
105 	than in terms of grace periods.  The legal number of non-zero
110 *	"Free-Block Circulation": Shows the number of torture structures
115 	passes through a grace period.  The last entry should be zero,
119 Different implementations of RCU can provide implementation-specific
123 …srcud-torture: Tree SRCU per-CPU(idx=0): 0(35,-21) 1(-4,24) 2(1,1) 3(-26,20) 4(28,-47) 5(-9,4) 6(-…
125 This line shows the per-CPU counter state, in this case for Tree SRCU
126 using a dynamically allocated srcu_struct (hence "srcud-" rather than
127 "srcu-").  The numbers in parentheses are the values of the "old" and
153 two are self-explanatory, while the last indicates that while there
154 were no RCU failures, CPU-hotplug problems were detected.
164 of modprobe and rmmod can be quite time-consuming and error-prone.
176 --cpus argument to kvm.sh.  For example, on a 64-CPU system, "--cpus 43"
180 the sixteen kernels).  The "--dryrun sched" argument will not run tests,
182 can be useful when working out how many CPUs to specify in the --cpus
186 to Tree SRCU might run only the SRCU-N and SRCU-P scenarios using the
187 --configs argument to kvm.sh as follows:  "--configs 'SRCU-N SRCU-P'".
192 	kvm.sh --cpus 448 --configs '5*CFLIST'
195 eight-CPU scenario::
197 	kvm.sh --cpus 448 --configs '56*TREE04'
199 Or 28 concurrent instances of each of two eight-CPU scenarios::
201 	kvm.sh --cpus 448 --configs '28*TREE03 28*TREE04'
204 limited using the --memory argument, which defaults to 512M.  Small
205 values for memory may require disabling the callback-flooding tests
206 using the --bootargs parameter discussed below.
208 Sometimes additional debugging is useful, and in such cases the --kconfig
209 parameter to kvm.sh may be used, for example, ``--kconfig 'CONFIG_KASAN=y'``.
213 CPU stall-warning code, use "--bootargs 'rcutorture.stall_cpu=30'".
216 require disabling rcutorture's callback-flooding tests::
218 	kvm.sh --cpus 448 --configs '56*TREE04' --memory 128M \
219 		--bootargs 'rcutorture.fwd_progress=0'
222 what the --buildonly argument does.
224 Finally, the --trust-make argument allows each kernel build to reuse what
234 given directory can be supplied to kvm-find-errors.sh in order to have
237 	tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh \
238 		tools/testing/selftests/rcutorture/res/2020.01.20-15.54.23
241 Files pertaining to all scenarios in a run reside in the top-level
242 directory (2020.01.20-15.54.23 in the example above), while per-scenario
244 "TREE04").  If a given scenario ran more than once (as in "--configs
249 The most frequently used file in the top-level directory is testid.txt.
253 The most frequently used files in each per-scenario-run directory are:
274 the following summary at the end of the run on a 12-CPU system::
276     SRCU-N ------- 804233 GPs (148.932/s) [srcu: g10008272 f0x0 ]
277     SRCU-P ------- 202320 GPs (37.4667/s) [srcud: g1809476 f0x0 ]
278     SRCU-t ------- 1122086 GPs (207.794/s) [srcu: g0 f0x0 ]
279     SRCU-u ------- 1111285 GPs (205.794/s) [srcud: g1 f0x0 ]
280     TASKS01 ------- 19666 GPs (3.64185/s) [tasks: g0 f0x0 ]
281     TASKS02 ------- 20541 GPs (3.80389/s) [tasks: g0 f0x0 ]
282     TASKS03 ------- 19416 GPs (3.59556/s) [tasks: g0 f0x0 ]
283     TINY01 ------- 836134 GPs (154.84/s) [rcu: g0 f0x0 ] n_max_cbs: 34198
284     TINY02 ------- 850371 GPs (157.476/s) [rcu: g0 f0x0 ] n_max_cbs: 2631
285     TREE01 ------- 162625 GPs (30.1157/s) [rcu: g1124169 f0x0 ]
286     TREE02 ------- 333003 GPs (61.6672/s) [rcu: g2647753 f0x0 ] n_max_cbs: 35844
287     TREE03 ------- 306623 GPs (56.782/s) [rcu: g2975325 f0x0 ] n_max_cbs: 1496497
289     TREE04 ------- 246149 GPs (45.5831/s) [rcu: g1695737 f0x0 ] n_max_cbs: 434961
290     TREE05 ------- 314603 GPs (58.2598/s) [rcu: g2257741 f0x2 ] n_max_cbs: 193997
291     TREE07 ------- 167347 GPs (30.9902/s) [rcu: g1079021 f0x0 ] n_max_cbs: 478732
293     TREE09 ------- 752238 GPs (139.303/s) [rcu: g13075057 f0x0 ] n_max_cbs: 99011