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