1 # SPDX-License-Identifier: GPL-2.0-only
2 #
3 # Timer subsystem related configuration option
4 #
5
6 # Options selectable by arch Kconfig
7
8 # Watchdog function for clocksources to detect
9 config CLOCKSOURCE_WATCHDOG
10 bool
11
12 # Architecture has extra clocksource data
13 config ARCH_CLOCKSOURCE_DATA
14 bool
15
16 # Architecture has extra clocksource init call
17 config ARCH_CLOCKSOURCE_INIT
18 bool
19
20 # Clocksources require validation of the clock
21 # cycle update - x86/TSC misfeature
22 config CLOCKSOURCE_VALIDATE_LAST_CYCLE
23 bool
24
25 # Timekeeping vsyscall support
26 config GENERIC_TIME_VSYSCALL
27 bool
28
29 # The generic clock events infrastructure
30 config GENERIC_CLOCKEVENTS
31 def_bool !LEGACY_TIMER_TICK
32
33 # Architecture can handle broadcast in a drive
34 config ARCH_HAS_TICK_BROADCAST
35 bool
36
37 # Clockevents broadcasting infrastructure
38 config GENERIC_CLOCKEVENTS_BROADCAST
39 bool
40 depends on GENERIC_CLOCKEVENTS
41
42 # Handle broadcast in default_idle_call()
43 config GENERIC_CLOCKEVENTS_BROADCAST_IDLE
44 bool
45 depends on GENERIC_CLOCKEVENTS_BROADCA
46
47 # Automatically adjust the min. reprogramming
48 # clock event device
49 config GENERIC_CLOCKEVENTS_MIN_ADJUST
50 bool
51
52 # Generic update of CMOS clock
53 config GENERIC_CMOS_UPDATE
54 bool
55
56 # Select to handle posix CPU timers from task_
57 # and not from the timer interrupt context
58 config HAVE_POSIX_CPU_TIMERS_TASK_WORK
59 bool
60
61 config POSIX_CPU_TIMERS_TASK_WORK
62 bool
63 default y if POSIX_TIMERS && HAVE_POSI
64
65 config LEGACY_TIMER_TICK
66 bool
67 help
68 The legacy timer tick helper is used
69 lack support for the generic clockev
70 New platforms should use generic clo
71
72 config TIME_KUNIT_TEST
73 tristate "KUnit test for kernel/time f
74 depends on KUNIT
75 default KUNIT_ALL_TESTS
76 help
77 Enable this option to test RTC libra
78
79 If unsure, say N.
80
81 config CONTEXT_TRACKING
82 bool
83
84 config CONTEXT_TRACKING_IDLE
85 bool
86 select CONTEXT_TRACKING
87 help
88 Tracks idle state on behalf of RCU.
89
90 if GENERIC_CLOCKEVENTS
91 menu "Timers subsystem"
92
93 # Core internal switch. Selected by NO_HZ_COMM
94 # only related to the tick functionality. Ones
95 # are supported independent of this.
96 config TICK_ONESHOT
97 bool
98
99 config NO_HZ_COMMON
100 bool
101 select TICK_ONESHOT
102
103 choice
104 prompt "Timer tick handling"
105 default NO_HZ_IDLE if NO_HZ
106
107 config HZ_PERIODIC
108 bool "Periodic timer ticks (constant r
109 help
110 This option keeps the tick running p
111 rate, even when the CPU doesn't need
112
113 config NO_HZ_IDLE
114 bool "Idle dynticks system (tickless i
115 select NO_HZ_COMMON
116 help
117 This option enables a tickless idle
118 will only trigger on an as-needed ba
119 This is usually interesting for ener
120
121 Most of the time you want to say Y h
122
123 config NO_HZ_FULL
124 bool "Full dynticks system (tickless)"
125 # NO_HZ_COMMON dependency
126 # We need at least one periodic CPU fo
127 depends on SMP
128 depends on HAVE_CONTEXT_TRACKING_USER
129 # VIRT_CPU_ACCOUNTING_GEN dependency
130 depends on HAVE_VIRT_CPU_ACCOUNTING_GE
131 select NO_HZ_COMMON
132 select RCU_NOCB_CPU
133 select VIRT_CPU_ACCOUNTING_GEN
134 select IRQ_WORK
135 select CPU_ISOLATION
136 help
137 Adaptively try to shutdown the tick w
138 the CPU is running tasks. Typically t
139 task on the CPU. Chances for running
140 the task mostly runs in userspace and
141
142 You need to fill up the nohz_full boo
143 desired range of dynticks CPUs to use
144 the expense of some overhead in user
145 syscalls, exceptions and interrupts.
146
147 By default, without passing the nohz_
148 like NO_HZ_IDLE.
149
150 If you're a distro say Y.
151
152 endchoice
153
154 config CONTEXT_TRACKING_USER
155 bool
156 depends on HAVE_CONTEXT_TRACKING_USER
157 select CONTEXT_TRACKING
158 help
159 Track transitions between kernel and
160 tickless cputime accounting. The for
161 tracking to enter/exit RCU extended
162
163 config CONTEXT_TRACKING_USER_FORCE
164 bool "Force user context tracking"
165 depends on CONTEXT_TRACKING_USER
166 default y if !NO_HZ_FULL
167 help
168 The major pre-requirement for full d
169 support the user context tracking su
170 other dependencies to provide in ord
171 dynticks working.
172
173 This option stands for testing when
174 user context tracking backend but do
175 requirements to make the full dyntic
176 Without the full dynticks, there is
177 for user context tracking and the su
178 userspace extended quiescent state a
179 accounting. This option copes with t
180 dynticks subsystem by forcing the us
181 CPUs in the system.
182
183 Say Y only if you're working on the
184 architecture backend for the user co
185
186 Say N otherwise, this option brings
187 don't want in production.
188
189 config NO_HZ
190 bool "Old Idle dynticks config"
191 help
192 This is the old config entry that en
193 We keep it around for a little while
194 compatibility with older config file
195
196 config HIGH_RES_TIMERS
197 bool "High Resolution Timer Support"
198 select TICK_ONESHOT
199 help
200 This option enables high resolution
201 hardware is not capable then this op
202 the size of the kernel image.
203
204 config CLOCKSOURCE_WATCHDOG_MAX_SKEW_US
205 int "Clocksource watchdog maximum allo
206 depends on CLOCKSOURCE_WATCHDOG
207 range 50 1000
208 default 125
209 help
210 Specify the maximum amount of allowa
211 microseconds before reporting the cl
212 The default is based on a half-secon
213 interval and NTP's maximum frequency
214 per million. If the clocksource is
215 it is good enough for the clocksourc
216
217 endmenu
218 endif
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