1This document gives a brief rationale for the TREE_RCU-related test
2cases, a group that includes PREEMPT_RCU.
3
4
5Kconfig Parameters:
6
7CONFIG_DEBUG_LOCK_ALLOC -- Do three, covering CONFIG_PROVE_LOCKING & not.
8CONFIG_DEBUG_OBJECTS_RCU_HEAD -- Do one.
9CONFIG_HOTPLUG_CPU -- Do half.  (Every second.)
10CONFIG_HZ_PERIODIC -- Do one.
11CONFIG_NO_HZ_IDLE -- Do those not otherwise specified. (Groups of two.)
12CONFIG_NO_HZ_FULL -- Do two, one with CONFIG_NO_HZ_FULL_SYSIDLE.
13CONFIG_NO_HZ_FULL_SYSIDLE -- Do one.
14CONFIG_PREEMPT -- Do half.  (First three and #8.)
15CONFIG_PROVE_LOCKING -- Do all but two, covering CONFIG_PROVE_RCU and not.
16CONFIG_PROVE_RCU -- Do all but one under CONFIG_PROVE_LOCKING.
17CONFIG_RCU_BOOST -- one of PREEMPT_RCU.
18CONFIG_RCU_KTHREAD_PRIO -- set to 2 for _BOOST testing.
19CONFIG_RCU_CPU_STALL_INFO -- Do one.
20CONFIG_RCU_FANOUT -- Cover hierarchy as currently, but overlap with others.
21CONFIG_RCU_FANOUT_EXACT -- Do one.
22CONFIG_RCU_FANOUT_LEAF -- Do one non-default.
23CONFIG_RCU_FAST_NO_HZ -- Do one, but not with CONFIG_RCU_NOCB_CPU_ALL.
24CONFIG_RCU_NOCB_CPU -- Do three, see below.
25CONFIG_RCU_NOCB_CPU_ALL -- Do one.
26CONFIG_RCU_NOCB_CPU_NONE -- Do one.
27CONFIG_RCU_NOCB_CPU_ZERO -- Do one.
28CONFIG_RCU_TRACE -- Do half.
29CONFIG_SMP -- Need one !SMP for PREEMPT_RCU.
30RCU-bh: Do one with PREEMPT and one with !PREEMPT.
31RCU-sched: Do one with PREEMPT but not BOOST.
32
33
34Hierarchy:
35
36TREE01.	CONFIG_NR_CPUS=8, CONFIG_RCU_FANOUT=8, CONFIG_RCU_FANOUT_EXACT=n.
37TREE02.	CONFIG_NR_CPUS=8, CONFIG_RCU_FANOUT=3, CONFIG_RCU_FANOUT_EXACT=n,
38	CONFIG_RCU_FANOUT_LEAF=3.
39TREE03.	CONFIG_NR_CPUS=8, CONFIG_RCU_FANOUT=4, CONFIG_RCU_FANOUT_EXACT=n,
40	CONFIG_RCU_FANOUT_LEAF=4.
41TREE04.	CONFIG_NR_CPUS=8, CONFIG_RCU_FANOUT=2, CONFIG_RCU_FANOUT_EXACT=n,
42	CONFIG_RCU_FANOUT_LEAF=2.
43TREE05.	CONFIG_NR_CPUS=8, CONFIG_RCU_FANOUT=6, CONFIG_RCU_FANOUT_EXACT=n
44	CONFIG_RCU_FANOUT_LEAF=6.
45TREE06.	CONFIG_NR_CPUS=8, CONFIG_RCU_FANOUT=6, CONFIG_RCU_FANOUT_EXACT=y
46	CONFIG_RCU_FANOUT_LEAF=6.
47TREE07.	CONFIG_NR_CPUS=16, CONFIG_RCU_FANOUT=2, CONFIG_RCU_FANOUT_EXACT=n,
48	CONFIG_RCU_FANOUT_LEAF=2.
49TREE08.	CONFIG_NR_CPUS=16, CONFIG_RCU_FANOUT=3, CONFIG_RCU_FANOUT_EXACT=y,
50	CONFIG_RCU_FANOUT_LEAF=2.
51TREE09.	CONFIG_NR_CPUS=1.
52
53
54Kconfig Parameters Ignored:
55
56CONFIG_64BIT
57
58	Used only to check CONFIG_RCU_FANOUT value, inspection suffices.
59
60CONFIG_NO_HZ_FULL_SYSIDLE_SMALL
61
62	Defer until Frederic uses this.
63
64CONFIG_PREEMPT_COUNT
65CONFIG_PREEMPT_RCU
66
67	Redundant with CONFIG_PREEMPT, ignore.
68
69CONFIG_RCU_BOOST_DELAY
70
71	Inspection suffices, ignore.
72
73CONFIG_RCU_CPU_STALL_TIMEOUT
74
75	Inspection suffices, ignore.
76
77CONFIG_RCU_STALL_COMMON
78
79	Implied by TREE_RCU and PREEMPT_RCU.
80
81CONFIG_RCU_TORTURE_TEST
82CONFIG_RCU_TORTURE_TEST_RUNNABLE
83
84	Always used in KVM testing.
85
86CONFIG_RCU_USER_QS
87
88	Redundant with CONFIG_NO_HZ_FULL.
89
90CONFIG_PREEMPT_RCU
91CONFIG_TREE_RCU
92
93	These are controlled by CONFIG_PREEMPT.
94