1 # SPDX-License-Identifier: GPL-2.0-only <<
2 # 1 #
3 # Timer subsystem related configuration option 2 # Timer subsystem related configuration options
4 # 3 #
5 4
6 # Options selectable by arch Kconfig 5 # Options selectable by arch Kconfig
7 6
8 # Watchdog function for clocksources to detect 7 # Watchdog function for clocksources to detect instabilities
9 config CLOCKSOURCE_WATCHDOG 8 config CLOCKSOURCE_WATCHDOG
10 bool 9 bool
11 10
12 # Architecture has extra clocksource data 11 # Architecture has extra clocksource data
13 config ARCH_CLOCKSOURCE_DATA 12 config ARCH_CLOCKSOURCE_DATA
14 bool 13 bool
15 14
16 # Architecture has extra clocksource init call !! 15 # Timekeeping vsyscall support
17 config ARCH_CLOCKSOURCE_INIT !! 16 config GENERIC_TIME_VSYSCALL
18 bool 17 bool
19 18
20 # Clocksources require validation of the clock !! 19 # Timekeeping vsyscall support
21 # cycle update - x86/TSC misfeature !! 20 config GENERIC_TIME_VSYSCALL_OLD
22 config CLOCKSOURCE_VALIDATE_LAST_CYCLE <<
23 bool 21 bool
24 22
25 # Timekeeping vsyscall support !! 23 # ktime_t scalar 64bit nsec representation
26 config GENERIC_TIME_VSYSCALL !! 24 config KTIME_SCALAR
>> 25 bool
>> 26
>> 27 # Old style timekeeping
>> 28 config ARCH_USES_GETTIMEOFFSET
27 bool 29 bool
28 30
29 # The generic clock events infrastructure 31 # The generic clock events infrastructure
30 config GENERIC_CLOCKEVENTS 32 config GENERIC_CLOCKEVENTS
31 def_bool !LEGACY_TIMER_TICK !! 33 bool
>> 34
>> 35 # Migration helper. Builds, but does not invoke
>> 36 config GENERIC_CLOCKEVENTS_BUILD
>> 37 bool
>> 38 default y
>> 39 depends on GENERIC_CLOCKEVENTS
32 40
33 # Architecture can handle broadcast in a drive 41 # Architecture can handle broadcast in a driver-agnostic way
34 config ARCH_HAS_TICK_BROADCAST 42 config ARCH_HAS_TICK_BROADCAST
35 bool 43 bool
36 44
37 # Clockevents broadcasting infrastructure 45 # Clockevents broadcasting infrastructure
38 config GENERIC_CLOCKEVENTS_BROADCAST 46 config GENERIC_CLOCKEVENTS_BROADCAST
39 bool 47 bool
40 depends on GENERIC_CLOCKEVENTS 48 depends on GENERIC_CLOCKEVENTS
41 49
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 50 # Automatically adjust the min. reprogramming time for
48 # clock event device 51 # clock event device
49 config GENERIC_CLOCKEVENTS_MIN_ADJUST 52 config GENERIC_CLOCKEVENTS_MIN_ADJUST
50 bool 53 bool
51 54
52 # Generic update of CMOS clock 55 # Generic update of CMOS clock
53 config GENERIC_CMOS_UPDATE 56 config GENERIC_CMOS_UPDATE
54 bool 57 bool
55 58
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 59 if GENERIC_CLOCKEVENTS
91 menu "Timers subsystem" 60 menu "Timers subsystem"
92 61
93 # Core internal switch. Selected by NO_HZ_COMM 62 # Core internal switch. Selected by NO_HZ_COMMON / HIGH_RES_TIMERS. This is
94 # only related to the tick functionality. Ones 63 # only related to the tick functionality. Oneshot clockevent devices
95 # are supported independent of this. !! 64 # are supported independ of this.
96 config TICK_ONESHOT 65 config TICK_ONESHOT
97 bool 66 bool
98 67
99 config NO_HZ_COMMON 68 config NO_HZ_COMMON
100 bool 69 bool
>> 70 depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
101 select TICK_ONESHOT 71 select TICK_ONESHOT
102 72
103 choice 73 choice
104 prompt "Timer tick handling" 74 prompt "Timer tick handling"
105 default NO_HZ_IDLE if NO_HZ 75 default NO_HZ_IDLE if NO_HZ
106 76
107 config HZ_PERIODIC 77 config HZ_PERIODIC
108 bool "Periodic timer ticks (constant r 78 bool "Periodic timer ticks (constant rate, no dynticks)"
109 help 79 help
110 This option keeps the tick running p 80 This option keeps the tick running periodically at a constant
111 rate, even when the CPU doesn't need 81 rate, even when the CPU doesn't need it.
112 82
113 config NO_HZ_IDLE 83 config NO_HZ_IDLE
114 bool "Idle dynticks system (tickless i 84 bool "Idle dynticks system (tickless idle)"
>> 85 depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
115 select NO_HZ_COMMON 86 select NO_HZ_COMMON
116 help 87 help
117 This option enables a tickless idle 88 This option enables a tickless idle system: timer interrupts
118 will only trigger on an as-needed ba 89 will only trigger on an as-needed basis when the system is idle.
119 This is usually interesting for ener 90 This is usually interesting for energy saving.
120 91
121 Most of the time you want to say Y h 92 Most of the time you want to say Y here.
122 93
123 config NO_HZ_FULL 94 config NO_HZ_FULL
124 bool "Full dynticks system (tickless)" 95 bool "Full dynticks system (tickless)"
125 # NO_HZ_COMMON dependency 96 # NO_HZ_COMMON dependency
>> 97 depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
126 # We need at least one periodic CPU fo 98 # We need at least one periodic CPU for timekeeping
127 depends on SMP 99 depends on SMP
128 depends on HAVE_CONTEXT_TRACKING_USER !! 100 # RCU_USER_QS dependency
>> 101 depends on HAVE_CONTEXT_TRACKING
129 # VIRT_CPU_ACCOUNTING_GEN dependency 102 # VIRT_CPU_ACCOUNTING_GEN dependency
130 depends on HAVE_VIRT_CPU_ACCOUNTING_GE !! 103 depends on 64BIT
131 select NO_HZ_COMMON 104 select NO_HZ_COMMON
>> 105 select RCU_USER_QS
132 select RCU_NOCB_CPU 106 select RCU_NOCB_CPU
133 select VIRT_CPU_ACCOUNTING_GEN 107 select VIRT_CPU_ACCOUNTING_GEN
>> 108 select CONTEXT_TRACKING_FORCE
134 select IRQ_WORK 109 select IRQ_WORK
135 select CPU_ISOLATION <<
136 help 110 help
137 Adaptively try to shutdown the tick w 111 Adaptively try to shutdown the tick whenever possible, even when
138 the CPU is running tasks. Typically t 112 the CPU is running tasks. Typically this requires running a single
139 task on the CPU. Chances for running 113 task on the CPU. Chances for running tickless are maximized when
140 the task mostly runs in userspace and 114 the task mostly runs in userspace and has few kernel activity.
141 115
142 You need to fill up the nohz_full boo 116 You need to fill up the nohz_full boot parameter with the
143 desired range of dynticks CPUs to use !! 117 desired range of dynticks CPUs.
144 the expense of some overhead in user <<
145 syscalls, exceptions and interrupts. <<
146 118
147 By default, without passing the nohz_ !! 119 This is implemented at the expense of some overhead in user <-> kernel
148 like NO_HZ_IDLE. !! 120 transitions: syscalls, exceptions and interrupts. Even when it's
>> 121 dynamically off.
149 122
150 If you're a distro say Y. !! 123 Say N.
151 124
152 endchoice 125 endchoice
153 126
154 config CONTEXT_TRACKING_USER !! 127 config NO_HZ_FULL_ALL
155 bool !! 128 bool "Full dynticks system on all CPUs by default"
156 depends on HAVE_CONTEXT_TRACKING_USER !! 129 depends on NO_HZ_FULL
157 select CONTEXT_TRACKING !! 130 help
158 help !! 131 If the user doesn't pass the nohz_full boot option to
159 Track transitions between kernel and !! 132 define the range of full dynticks CPUs, consider that all
160 tickless cputime accounting. The for !! 133 CPUs in the system are full dynticks by default.
161 tracking to enter/exit RCU extended !! 134 Note the boot CPU will still be kept outside the range to
162 !! 135 handle the timekeeping duty.
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. <<
188 136
189 config NO_HZ 137 config NO_HZ
190 bool "Old Idle dynticks config" 138 bool "Old Idle dynticks config"
>> 139 depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
191 help 140 help
192 This is the old config entry that en 141 This is the old config entry that enables dynticks idle.
193 We keep it around for a little while 142 We keep it around for a little while to enforce backward
194 compatibility with older config file 143 compatibility with older config files.
195 144
196 config HIGH_RES_TIMERS 145 config HIGH_RES_TIMERS
197 bool "High Resolution Timer Support" 146 bool "High Resolution Timer Support"
>> 147 depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
198 select TICK_ONESHOT 148 select TICK_ONESHOT
199 help 149 help
200 This option enables high resolution 150 This option enables high resolution timer support. If your
201 hardware is not capable then this op 151 hardware is not capable then this option only increases
202 the size of the kernel image. 152 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 <<
216 153
217 endmenu 154 endmenu
218 endif 155 endif
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