1ec8f24b7SThomas Gleixner# SPDX-License-Identifier: GPL-2.0-only 279bf2bb3SThomas Gleixner# 379bf2bb3SThomas Gleixner# Timer subsystem related configuration options 479bf2bb3SThomas Gleixner# 53872c48bSThomas Gleixner 6b5e498adSThomas Gleixner# Options selectable by arch Kconfig 7b5e498adSThomas Gleixner 8b5e498adSThomas Gleixner# Watchdog function for clocksources to detect instabilities 9b5e498adSThomas Gleixnerconfig CLOCKSOURCE_WATCHDOG 10b5e498adSThomas Gleixner bool 11b5e498adSThomas Gleixner 12b5e498adSThomas Gleixner# Architecture has extra clocksource data 13b5e498adSThomas Gleixnerconfig ARCH_CLOCKSOURCE_DATA 14b5e498adSThomas Gleixner bool 15b5e498adSThomas Gleixner 16d67f34c1SThomas Gleixner# Architecture has extra clocksource init called from registration 17d67f34c1SThomas Gleixnerconfig ARCH_CLOCKSOURCE_INIT 18d67f34c1SThomas Gleixner bool 19d67f34c1SThomas Gleixner 2009ec5442SThomas Gleixner# Clocksources require validation of the clocksource against the last 2109ec5442SThomas Gleixner# cycle update - x86/TSC misfeature 2209ec5442SThomas Gleixnerconfig CLOCKSOURCE_VALIDATE_LAST_CYCLE 2309ec5442SThomas Gleixner bool 2409ec5442SThomas Gleixner 25b5e498adSThomas Gleixner# Timekeeping vsyscall support 26576094b7SJohn Stultzconfig GENERIC_TIME_VSYSCALL 27576094b7SJohn Stultz bool 28576094b7SJohn Stultz 29b5e498adSThomas Gleixner# The generic clock events infrastructure 30b5e498adSThomas Gleixnerconfig GENERIC_CLOCKEVENTS 310774a6edSArnd Bergmann def_bool !LEGACY_TIMER_TICK 32b5e498adSThomas Gleixner 3312ad1000SMark Rutland# Architecture can handle broadcast in a driver-agnostic way 3412ad1000SMark Rutlandconfig ARCH_HAS_TICK_BROADCAST 3512ad1000SMark Rutland bool 3612ad1000SMark Rutland 37b5e498adSThomas Gleixner# Clockevents broadcasting infrastructure 38b5e498adSThomas Gleixnerconfig GENERIC_CLOCKEVENTS_BROADCAST 39b5e498adSThomas Gleixner bool 40b5e498adSThomas Gleixner depends on GENERIC_CLOCKEVENTS 41b5e498adSThomas Gleixner 42764e0da1SThomas Gleixner# Automatically adjust the min. reprogramming time for 43764e0da1SThomas Gleixner# clock event device 44764e0da1SThomas Gleixnerconfig GENERIC_CLOCKEVENTS_MIN_ADJUST 45764e0da1SThomas Gleixner bool 46764e0da1SThomas Gleixner 47b5e498adSThomas Gleixner# Generic update of CMOS clock 48b5e498adSThomas Gleixnerconfig GENERIC_CMOS_UPDATE 49b5e498adSThomas Gleixner bool 50764e0da1SThomas Gleixner 511fb497ddSThomas Gleixner# Select to handle posix CPU timers from task_work 521fb497ddSThomas Gleixner# and not from the timer interrupt context 531fb497ddSThomas Gleixnerconfig HAVE_POSIX_CPU_TIMERS_TASK_WORK 541fb497ddSThomas Gleixner bool 551fb497ddSThomas Gleixner 561fb497ddSThomas Gleixnerconfig POSIX_CPU_TIMERS_TASK_WORK 571fb497ddSThomas Gleixner bool 581fb497ddSThomas Gleixner default y if POSIX_TIMERS && HAVE_POSIX_CPU_TIMERS_TASK_WORK 591fb497ddSThomas Gleixner 60b3550164SArnd Bergmannconfig LEGACY_TIMER_TICK 61b3550164SArnd Bergmann bool 62b3550164SArnd Bergmann help 63b3550164SArnd Bergmann The legacy timer tick helper is used by platforms that 64b3550164SArnd Bergmann lack support for the generic clockevent framework. 65b3550164SArnd Bergmann New platforms should use generic clockevents instead. 66b3550164SArnd Bergmann 6727601055SCassio Nericonfig TIME_KUNIT_TEST 6827601055SCassio Neri tristate "KUnit test for kernel/time functions" if !KUNIT_ALL_TESTS 6927601055SCassio Neri depends on KUNIT 7027601055SCassio Neri default KUNIT_ALL_TESTS 7127601055SCassio Neri help 7227601055SCassio Neri Enable this option to test RTC library functions. 7327601055SCassio Neri 7427601055SCassio Neri If unsure, say N. 7527601055SCassio Neri 76*24a9c541SFrederic Weisbeckerconfig CONTEXT_TRACKING 77*24a9c541SFrederic Weisbecker bool 78*24a9c541SFrederic Weisbecker 79764e0da1SThomas Gleixnerif GENERIC_CLOCKEVENTS 80764e0da1SThomas Gleixnermenu "Timers subsystem" 81764e0da1SThomas Gleixner 823451d024SFrederic Weisbecker# Core internal switch. Selected by NO_HZ_COMMON / HIGH_RES_TIMERS. This is 83764e0da1SThomas Gleixner# only related to the tick functionality. Oneshot clockevent devices 846082a6e4SRandy Dunlap# are supported independent of this. 85764e0da1SThomas Gleixnerconfig TICK_ONESHOT 86764e0da1SThomas Gleixner bool 87764e0da1SThomas Gleixner 883451d024SFrederic Weisbeckerconfig NO_HZ_COMMON 893451d024SFrederic Weisbecker bool 903451d024SFrederic Weisbecker select TICK_ONESHOT 913451d024SFrederic Weisbecker 923ca277e4SFrederic Weisbeckerchoice 933ca277e4SFrederic Weisbecker prompt "Timer tick handling" 943ca277e4SFrederic Weisbecker default NO_HZ_IDLE if NO_HZ 953ca277e4SFrederic Weisbecker 965b533f4fSFrederic Weisbeckerconfig HZ_PERIODIC 973ca277e4SFrederic Weisbecker bool "Periodic timer ticks (constant rate, no dynticks)" 983ca277e4SFrederic Weisbecker help 993ca277e4SFrederic Weisbecker This option keeps the tick running periodically at a constant 1003ca277e4SFrederic Weisbecker rate, even when the CPU doesn't need it. 1013ca277e4SFrederic Weisbecker 1023ca277e4SFrederic Weisbeckerconfig NO_HZ_IDLE 1033ca277e4SFrederic Weisbecker bool "Idle dynticks system (tickless idle)" 1043451d024SFrederic Weisbecker select NO_HZ_COMMON 105764e0da1SThomas Gleixner help 1063ca277e4SFrederic Weisbecker This option enables a tickless idle system: timer interrupts 1073ca277e4SFrederic Weisbecker will only trigger on an as-needed basis when the system is idle. 1083ca277e4SFrederic Weisbecker This is usually interesting for energy saving. 1093ca277e4SFrederic Weisbecker 1103ca277e4SFrederic Weisbecker Most of the time you want to say Y here. 111764e0da1SThomas Gleixner 112c5bfece2SFrederic Weisbeckerconfig NO_HZ_FULL 113fae30dd6SFrederic Weisbecker bool "Full dynticks system (tickless)" 1143451d024SFrederic Weisbecker # NO_HZ_COMMON dependency 115fae30dd6SFrederic Weisbecker # We need at least one periodic CPU for timekeeping 116fae30dd6SFrederic Weisbecker depends on SMP 117*24a9c541SFrederic Weisbecker depends on HAVE_CONTEXT_TRACKING_USER 118c58b0df1SFrederic Weisbecker # VIRT_CPU_ACCOUNTING_GEN dependency 119554b0004SKevin Hilman depends on HAVE_VIRT_CPU_ACCOUNTING_GEN 1203451d024SFrederic Weisbecker select NO_HZ_COMMON 121ab71d36dSFrederic Weisbecker select RCU_NOCB_CPU 122c58b0df1SFrederic Weisbecker select VIRT_CPU_ACCOUNTING_GEN 12376c24fb0SFrederic Weisbecker select IRQ_WORK 124bf29cb23SPaul E. McKenney select CPU_ISOLATION 125a831881bSFrederic Weisbecker help 126a831881bSFrederic Weisbecker Adaptively try to shutdown the tick whenever possible, even when 127a831881bSFrederic Weisbecker the CPU is running tasks. Typically this requires running a single 128a831881bSFrederic Weisbecker task on the CPU. Chances for running tickless are maximized when 129a831881bSFrederic Weisbecker the task mostly runs in userspace and has few kernel activity. 130a831881bSFrederic Weisbecker 131c5bfece2SFrederic Weisbecker You need to fill up the nohz_full boot parameter with the 132176b8906SFrederic Weisbecker desired range of dynticks CPUs to use it. This is implemented at 133176b8906SFrederic Weisbecker the expense of some overhead in user <-> kernel transitions: 134176b8906SFrederic Weisbecker syscalls, exceptions and interrupts. 135a831881bSFrederic Weisbecker 136176b8906SFrederic Weisbecker By default, without passing the nohz_full parameter, this behaves just 137176b8906SFrederic Weisbecker like NO_HZ_IDLE. 138a831881bSFrederic Weisbecker 139176b8906SFrederic Weisbecker If you're a distro say Y. 140a831881bSFrederic Weisbecker 1413ca277e4SFrederic Weisbeckerendchoice 1423ca277e4SFrederic Weisbecker 143*24a9c541SFrederic Weisbeckerconfig CONTEXT_TRACKING_USER 144a4cffdadSPaul E. McKenney bool 145*24a9c541SFrederic Weisbecker depends on HAVE_CONTEXT_TRACKING_USER 146*24a9c541SFrederic Weisbecker select CONTEXT_TRACKING 147*24a9c541SFrederic Weisbecker help 148*24a9c541SFrederic Weisbecker Track transitions between kernel and user on behalf of RCU and 149*24a9c541SFrederic Weisbecker tickless cputime accounting. The former case relies on context 150*24a9c541SFrederic Weisbecker tracking to enter/exit RCU extended quiescent states. 151a4cffdadSPaul E. McKenney 152*24a9c541SFrederic Weisbeckerconfig CONTEXT_TRACKING_USER_FORCE 153*24a9c541SFrederic Weisbecker bool "Force user context tracking" 154*24a9c541SFrederic Weisbecker depends on CONTEXT_TRACKING_USER 155a4cffdadSPaul E. McKenney default y if !NO_HZ_FULL 156a4cffdadSPaul E. McKenney help 157a4cffdadSPaul E. McKenney The major pre-requirement for full dynticks to work is to 158*24a9c541SFrederic Weisbecker support the user context tracking subsystem. But there are also 159a4cffdadSPaul E. McKenney other dependencies to provide in order to make the full 160a4cffdadSPaul E. McKenney dynticks working. 161a4cffdadSPaul E. McKenney 162a4cffdadSPaul E. McKenney This option stands for testing when an arch implements the 163*24a9c541SFrederic Weisbecker user context tracking backend but doesn't yet fulfill all the 164a4cffdadSPaul E. McKenney requirements to make the full dynticks feature working. 165a4cffdadSPaul E. McKenney Without the full dynticks, there is no way to test the support 166*24a9c541SFrederic Weisbecker for user context tracking and the subsystems that rely on it: RCU 167a4cffdadSPaul E. McKenney userspace extended quiescent state and tickless cputime 168a4cffdadSPaul E. McKenney accounting. This option copes with the absence of the full 169*24a9c541SFrederic Weisbecker dynticks subsystem by forcing the user context tracking on all 170a4cffdadSPaul E. McKenney CPUs in the system. 171a4cffdadSPaul E. McKenney 172a4cffdadSPaul E. McKenney Say Y only if you're working on the development of an 173*24a9c541SFrederic Weisbecker architecture backend for the user context tracking. 174a4cffdadSPaul E. McKenney 175a4cffdadSPaul E. McKenney Say N otherwise, this option brings an overhead that you 176a4cffdadSPaul E. McKenney don't want in production. 177a4cffdadSPaul E. McKenney 1780644ca5cSFrederic Weisbeckerconfig NO_HZ 1790644ca5cSFrederic Weisbecker bool "Old Idle dynticks config" 1800644ca5cSFrederic Weisbecker help 1810644ca5cSFrederic Weisbecker This is the old config entry that enables dynticks idle. 1820644ca5cSFrederic Weisbecker We keep it around for a little while to enforce backward 1830644ca5cSFrederic Weisbecker compatibility with older config files. 1840644ca5cSFrederic Weisbecker 185764e0da1SThomas Gleixnerconfig HIGH_RES_TIMERS 186764e0da1SThomas Gleixner bool "High Resolution Timer Support" 187764e0da1SThomas Gleixner select TICK_ONESHOT 188764e0da1SThomas Gleixner help 189764e0da1SThomas Gleixner This option enables high resolution timer support. If your 190764e0da1SThomas Gleixner hardware is not capable then this option only increases 191764e0da1SThomas Gleixner the size of the kernel image. 192764e0da1SThomas Gleixner 193fc153c1cSWaiman Longconfig CLOCKSOURCE_WATCHDOG_MAX_SKEW_US 194fc153c1cSWaiman Long int "Clocksource watchdog maximum allowable skew (in μs)" 195fc153c1cSWaiman Long depends on CLOCKSOURCE_WATCHDOG 196fc153c1cSWaiman Long range 50 1000 197fc153c1cSWaiman Long default 100 198fc153c1cSWaiman Long help 199fc153c1cSWaiman Long Specify the maximum amount of allowable watchdog skew in 200fc153c1cSWaiman Long microseconds before reporting the clocksource to be unstable. 201fc153c1cSWaiman Long 202764e0da1SThomas Gleixnerendmenu 203764e0da1SThomas Gleixnerendif 204