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-rw-r--r--init/Kconfig179
1 files changed, 92 insertions, 87 deletions
diff --git a/init/Kconfig b/init/Kconfig
index 2af83825634e..3be35f3a001b 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -238,6 +238,98 @@ config AUDIT_TREE
238 def_bool y 238 def_bool y
239 depends on AUDITSYSCALL && INOTIFY 239 depends on AUDITSYSCALL && INOTIFY
240 240
241menu "RCU Subsystem"
242
243choice
244 prompt "RCU Implementation"
245 default CLASSIC_RCU
246
247config CLASSIC_RCU
248 bool "Classic RCU"
249 help
250 This option selects the classic RCU implementation that is
251 designed for best read-side performance on non-realtime
252 systems.
253
254 Select this option if you are unsure.
255
256config TREE_RCU
257 bool "Tree-based hierarchical RCU"
258 help
259 This option selects the RCU implementation that is
260 designed for very large SMP system with hundreds or
261 thousands of CPUs.
262
263config PREEMPT_RCU
264 bool "Preemptible RCU"
265 depends on PREEMPT
266 help
267 This option reduces the latency of the kernel by making certain
268 RCU sections preemptible. Normally RCU code is non-preemptible, if
269 this option is selected then read-only RCU sections become
270 preemptible. This helps latency, but may expose bugs due to
271 now-naive assumptions about each RCU read-side critical section
272 remaining on a given CPU through its execution.
273
274endchoice
275
276config RCU_TRACE
277 bool "Enable tracing for RCU"
278 depends on TREE_RCU || PREEMPT_RCU
279 help
280 This option provides tracing in RCU which presents stats
281 in debugfs for debugging RCU implementation.
282
283 Say Y here if you want to enable RCU tracing
284 Say N if you are unsure.
285
286config RCU_FANOUT
287 int "Tree-based hierarchical RCU fanout value"
288 range 2 64 if 64BIT
289 range 2 32 if !64BIT
290 depends on TREE_RCU
291 default 64 if 64BIT
292 default 32 if !64BIT
293 help
294 This option controls the fanout of hierarchical implementations
295 of RCU, allowing RCU to work efficiently on machines with
296 large numbers of CPUs. This value must be at least the cube
297 root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
298 systems and up to 262,144 for 64-bit systems.
299
300 Select a specific number if testing RCU itself.
301 Take the default if unsure.
302
303config RCU_FANOUT_EXACT
304 bool "Disable tree-based hierarchical RCU auto-balancing"
305 depends on TREE_RCU
306 default n
307 help
308 This option forces use of the exact RCU_FANOUT value specified,
309 regardless of imbalances in the hierarchy. This is useful for
310 testing RCU itself, and might one day be useful on systems with
311 strong NUMA behavior.
312
313 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
314
315 Say N if unsure.
316
317config TREE_RCU_TRACE
318 def_bool RCU_TRACE && TREE_RCU
319 select DEBUG_FS
320 help
321 This option provides tracing for the TREE_RCU implementation,
322 permitting Makefile to trivially select kernel/rcutree_trace.c.
323
324config PREEMPT_RCU_TRACE
325 def_bool RCU_TRACE && PREEMPT_RCU
326 select DEBUG_FS
327 help
328 This option provides tracing for the PREEMPT_RCU implementation,
329 permitting Makefile to trivially select kernel/rcupreempt_trace.c.
330
331endmenu # "RCU Subsystem"
332
241config IKCONFIG 333config IKCONFIG
242 tristate "Kernel .config support" 334 tristate "Kernel .config support"
243 ---help--- 335 ---help---
@@ -972,90 +1064,3 @@ source "block/Kconfig"
972config PREEMPT_NOTIFIERS 1064config PREEMPT_NOTIFIERS
973 bool 1065 bool
974 1066
975choice
976 prompt "RCU Implementation"
977 default CLASSIC_RCU
978
979config CLASSIC_RCU
980 bool "Classic RCU"
981 help
982 This option selects the classic RCU implementation that is
983 designed for best read-side performance on non-realtime
984 systems.
985
986 Select this option if you are unsure.
987
988config TREE_RCU
989 bool "Tree-based hierarchical RCU"
990 help
991 This option selects the RCU implementation that is
992 designed for very large SMP system with hundreds or
993 thousands of CPUs.
994
995config PREEMPT_RCU
996 bool "Preemptible RCU"
997 depends on PREEMPT
998 help
999 This option reduces the latency of the kernel by making certain
1000 RCU sections preemptible. Normally RCU code is non-preemptible, if
1001 this option is selected then read-only RCU sections become
1002 preemptible. This helps latency, but may expose bugs due to
1003 now-naive assumptions about each RCU read-side critical section
1004 remaining on a given CPU through its execution.
1005
1006endchoice
1007
1008config RCU_TRACE
1009 bool "Enable tracing for RCU"
1010 depends on TREE_RCU || PREEMPT_RCU
1011 help
1012 This option provides tracing in RCU which presents stats
1013 in debugfs for debugging RCU implementation.
1014
1015 Say Y here if you want to enable RCU tracing
1016 Say N if you are unsure.
1017
1018config RCU_FANOUT
1019 int "Tree-based hierarchical RCU fanout value"
1020 range 2 64 if 64BIT
1021 range 2 32 if !64BIT
1022 depends on TREE_RCU
1023 default 64 if 64BIT
1024 default 32 if !64BIT
1025 help
1026 This option controls the fanout of hierarchical implementations
1027 of RCU, allowing RCU to work efficiently on machines with
1028 large numbers of CPUs. This value must be at least the cube
1029 root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
1030 systems and up to 262,144 for 64-bit systems.
1031
1032 Select a specific number if testing RCU itself.
1033 Take the default if unsure.
1034
1035config RCU_FANOUT_EXACT
1036 bool "Disable tree-based hierarchical RCU auto-balancing"
1037 depends on TREE_RCU
1038 default n
1039 help
1040 This option forces use of the exact RCU_FANOUT value specified,
1041 regardless of imbalances in the hierarchy. This is useful for
1042 testing RCU itself, and might one day be useful on systems with
1043 strong NUMA behavior.
1044
1045 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
1046
1047 Say N if unsure.
1048
1049config TREE_RCU_TRACE
1050 def_bool RCU_TRACE && TREE_RCU
1051 select DEBUG_FS
1052 help
1053 This option provides tracing for the TREE_RCU implementation,
1054 permitting Makefile to trivially select kernel/rcutree_trace.c.
1055
1056config PREEMPT_RCU_TRACE
1057 def_bool RCU_TRACE && PREEMPT_RCU
1058 select DEBUG_FS
1059 help
1060 This option provides tracing for the PREEMPT_RCU implementation,
1061 permitting Makefile to trivially select kernel/rcupreempt_trace.c.