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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 | # SPDX-License-Identifier: GPL-2.0-only # # Timer subsystem related configuration options # # Options selectable by arch Kconfig # Watchdog function for clocksources to detect instabilities config CLOCKSOURCE_WATCHDOG bool # Architecture has extra clocksource data config ARCH_CLOCKSOURCE_DATA bool # Architecture has extra clocksource init called from registration config ARCH_CLOCKSOURCE_INIT bool # Clocksources require validation of the clocksource against the last # cycle update - x86/TSC misfeature config CLOCKSOURCE_VALIDATE_LAST_CYCLE bool # Timekeeping vsyscall support config GENERIC_TIME_VSYSCALL bool # Old style timekeeping config ARCH_USES_GETTIMEOFFSET bool # The generic clock events infrastructure config GENERIC_CLOCKEVENTS bool # Architecture can handle broadcast in a driver-agnostic way config ARCH_HAS_TICK_BROADCAST bool # Clockevents broadcasting infrastructure config GENERIC_CLOCKEVENTS_BROADCAST bool depends on GENERIC_CLOCKEVENTS # Automatically adjust the min. reprogramming time for # clock event device config GENERIC_CLOCKEVENTS_MIN_ADJUST bool # Generic update of CMOS clock config GENERIC_CMOS_UPDATE bool # Select to handle posix CPU timers from task_work # and not from the timer interrupt context config HAVE_POSIX_CPU_TIMERS_TASK_WORK bool config POSIX_CPU_TIMERS_TASK_WORK bool default y if POSIX_TIMERS && HAVE_POSIX_CPU_TIMERS_TASK_WORK if GENERIC_CLOCKEVENTS menu "Timers subsystem" # Core internal switch. Selected by NO_HZ_COMMON / HIGH_RES_TIMERS. This is # only related to the tick functionality. Oneshot clockevent devices # are supported independent of this. config TICK_ONESHOT bool config NO_HZ_COMMON bool depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS select TICK_ONESHOT choice prompt "Timer tick handling" default NO_HZ_IDLE if NO_HZ config HZ_PERIODIC bool "Periodic timer ticks (constant rate, no dynticks)" help This option keeps the tick running periodically at a constant rate, even when the CPU doesn't need it. config NO_HZ_IDLE bool "Idle dynticks system (tickless idle)" depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS select NO_HZ_COMMON help This option enables a tickless idle system: timer interrupts will only trigger on an as-needed basis when the system is idle. This is usually interesting for energy saving. Most of the time you want to say Y here. config NO_HZ_FULL bool "Full dynticks system (tickless)" # NO_HZ_COMMON dependency depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS # We need at least one periodic CPU for timekeeping depends on SMP depends on HAVE_CONTEXT_TRACKING # VIRT_CPU_ACCOUNTING_GEN dependency depends on HAVE_VIRT_CPU_ACCOUNTING_GEN select NO_HZ_COMMON select RCU_NOCB_CPU select VIRT_CPU_ACCOUNTING_GEN select IRQ_WORK select CPU_ISOLATION help Adaptively try to shutdown the tick whenever possible, even when the CPU is running tasks. Typically this requires running a single task on the CPU. Chances for running tickless are maximized when the task mostly runs in userspace and has few kernel activity. You need to fill up the nohz_full boot parameter with the desired range of dynticks CPUs. This is implemented at the expense of some overhead in user <-> kernel transitions: syscalls, exceptions and interrupts. Even when it's dynamically off. Say N. endchoice config CONTEXT_TRACKING bool config CONTEXT_TRACKING_FORCE bool "Force context tracking" depends on CONTEXT_TRACKING default y if !NO_HZ_FULL help The major pre-requirement for full dynticks to work is to support the context tracking subsystem. But there are also other dependencies to provide in order to make the full dynticks working. This option stands for testing when an arch implements the context tracking backend but doesn't yet fullfill all the requirements to make the full dynticks feature working. Without the full dynticks, there is no way to test the support for context tracking and the subsystems that rely on it: RCU userspace extended quiescent state and tickless cputime accounting. This option copes with the absence of the full dynticks subsystem by forcing the context tracking on all CPUs in the system. Say Y only if you're working on the development of an architecture backend for the context tracking. Say N otherwise, this option brings an overhead that you don't want in production. config NO_HZ bool "Old Idle dynticks config" depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS help This is the old config entry that enables dynticks idle. We keep it around for a little while to enforce backward compatibility with older config files. config HIGH_RES_TIMERS bool "High Resolution Timer Support" depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS select TICK_ONESHOT help This option enables high resolution timer support. If your hardware is not capable then this option only increases the size of the kernel image. endmenu endif |