## Timer subsystem related configuration options# # Options selectable by arch Kconfig # Watchdog function for clocksources to detect instabilitiesconfig CLOCKSOURCE_WATCHDOG	bool # Architecture has extra clocksource dataconfig ARCH_CLOCKSOURCE_DATA	bool # Architecture has extra clocksource init called from registrationconfig ARCH_CLOCKSOURCE_INIT	bool # Clocksources require validation of the clocksource against the last# cycle update - x86/TSC misfeatureconfig CLOCKSOURCE_VALIDATE_LAST_CYCLE	bool # Timekeeping vsyscall supportconfig GENERIC_TIME_VSYSCALL	bool # Old style timekeepingconfig ARCH_USES_GETTIMEOFFSET	bool # The generic clock events infrastructureconfig GENERIC_CLOCKEVENTS	bool # Architecture can handle broadcast in a driver-agnostic wayconfig ARCH_HAS_TICK_BROADCAST	bool # Clockevents broadcasting infrastructureconfig GENERIC_CLOCKEVENTS_BROADCAST	bool	depends on GENERIC_CLOCKEVENTS # Automatically adjust the min. reprogramming time for# clock event deviceconfig GENERIC_CLOCKEVENTS_MIN_ADJUST	bool # Generic update of CMOS clockconfig GENERIC_CMOS_UPDATE	bool if GENERIC_CLOCKEVENTSmenu "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. endmenuendif