[deliverable/linux.git] / kernel / time / Kconfig

#
# 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

# Platforms has a persistent clock
config ALWAYS_USE_PERSISTENT_CLOCK
	bool
	default n

# Timekeeping vsyscall support
config GENERIC_TIME_VSYSCALL
	bool

# Timekeeping vsyscall support
config GENERIC_TIME_VSYSCALL_OLD
	bool

# ktime_t scalar 64bit nsec representation
config KTIME_SCALAR
	bool

# Old style timekeeping
config ARCH_USES_GETTIMEOFFSET
	bool

# The generic clock events infrastructure
config GENERIC_CLOCKEVENTS
	bool

# Migration helper. Builds, but does not invoke
config GENERIC_CLOCKEVENTS_BUILD
	bool
	default y
	depends on GENERIC_CLOCKEVENTS

# 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

if GENERIC_CLOCKEVENTS
menu "Timers subsystem"

# Core internal switch. Selected by NO_HZ / HIGH_RES_TIMERS. This is
# only related to the tick functionality. Oneshot clockevent devices
# are supported independ of this.
config TICK_ONESHOT
	bool

config NO_HZ
	bool "Tickless System (Dynamic Ticks)"
	depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
	select TICK_ONESHOT
	help
	  This option enables a tickless system: timer interrupts will
	  only trigger on an as-needed basis both when the system is
	  busy and when the system is idle.

config NO_HZ_EXTENDED
	bool "Full dynticks system"
	# NO_HZ dependency
	depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
	# RCU_USER_QS
	depends on HAVE_CONTEXT_TRACKING && SMP
	# RCU_NOCB_CPU dependency
	depends on TREE_RCU || TREE_PREEMPT_RCU
	depends on VIRT_CPU_ACCOUNTING_GEN
	select NO_HZ
	select RCU_USER_QS
	select RCU_NOCB_CPU
	select CONTEXT_TRACKING_FORCE
	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_extended 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.

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
Commit	Line	Data
79bf2bb3 TG	1	#
	2	# Timer subsystem related configuration options
	3	#
3872c48b	4
b5e498ad TG	5	# Options selectable by arch Kconfig
	6
	7	# Watchdog function for clocksources to detect instabilities
	8	config CLOCKSOURCE_WATCHDOG
	9	bool
	10
	11	# Architecture has extra clocksource data
	12	config ARCH_CLOCKSOURCE_DATA
	13	bool
	14
05ad717c	15	# Platforms has a persistent clock
6f16eebe	16	config ALWAYS_USE_PERSISTENT_CLOCK
05ad717c FT	17	bool
	18	default n
	19
576094b7 JS	20	# Timekeeping vsyscall support
	21	config GENERIC_TIME_VSYSCALL
	22	bool
	23
b5e498ad	24	# Timekeeping vsyscall support
70639421	25	config GENERIC_TIME_VSYSCALL_OLD
b5e498ad TG	26	bool
	27
	28	# ktime_t scalar 64bit nsec representation
	29	config KTIME_SCALAR
	30	bool
	31
	32	# Old style timekeeping
	33	config ARCH_USES_GETTIMEOFFSET
	34	bool
	35
	36	# The generic clock events infrastructure
	37	config GENERIC_CLOCKEVENTS
	38	bool
	39
764e0da1 TG	40	# Migration helper. Builds, but does not invoke
	41	config GENERIC_CLOCKEVENTS_BUILD
	42	bool
	43	default y
	44	depends on GENERIC_CLOCKEVENTS
	45
12ad1000 MR	46	# Architecture can handle broadcast in a driver-agnostic way
	47	config ARCH_HAS_TICK_BROADCAST
	48	bool
	49
b5e498ad TG	50	# Clockevents broadcasting infrastructure
	51	config GENERIC_CLOCKEVENTS_BROADCAST
	52	bool
	53	depends on GENERIC_CLOCKEVENTS
	54
764e0da1 TG	55	# Automatically adjust the min. reprogramming time for
	56	# clock event device
	57	config GENERIC_CLOCKEVENTS_MIN_ADJUST
	58	bool
	59
b5e498ad TG	60	# Generic update of CMOS clock
	61	config GENERIC_CMOS_UPDATE
	62	bool
764e0da1 TG	63
	64	if GENERIC_CLOCKEVENTS
	65	menu "Timers subsystem"
	66
	67	# Core internal switch. Selected by NO_HZ / HIGH_RES_TIMERS. This is
	68	# only related to the tick functionality. Oneshot clockevent devices
	69	# are supported independ of this.
	70	config TICK_ONESHOT
	71	bool
	72
	73	config NO_HZ
	74	bool "Tickless System (Dynamic Ticks)"
	75	depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
	76	select TICK_ONESHOT
	77	help
	78	This option enables a tickless system: timer interrupts will
	79	only trigger on an as-needed basis both when the system is
	80	busy and when the system is idle.
	81
a831881b	82	config NO_HZ_EXTENDED
ab71d36d FW	83	bool "Full dynticks system"
	84	# NO_HZ dependency
	85	depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
	86	# RCU_USER_QS
	87	depends on HAVE_CONTEXT_TRACKING && SMP
	88	# RCU_NOCB_CPU dependency
	89	depends on TREE_RCU \|\| TREE_PREEMPT_RCU
	90	depends on VIRT_CPU_ACCOUNTING_GEN
	91	select NO_HZ
	92	select RCU_USER_QS
	93	select RCU_NOCB_CPU
	94	select CONTEXT_TRACKING_FORCE
	95	help
	96	Adaptively try to shutdown the tick whenever possible, even when
a831881b FW	97	the CPU is running tasks. Typically this requires running a single
	98	task on the CPU. Chances for running tickless are maximized when
	99	the task mostly runs in userspace and has few kernel activity.
	100
	101	You need to fill up the nohz_extended boot parameter with the
	102	desired range of dynticks CPUs.
	103
	104	This is implemented at the expense of some overhead in user <-> kernel
	105	transitions: syscalls, exceptions and interrupts. Even when it's
	106	dynamically off.
	107
	108	Say N.
	109
764e0da1 TG	110	config HIGH_RES_TIMERS
	111	bool "High Resolution Timer Support"
	112	depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
	113	select TICK_ONESHOT
	114	help
	115	This option enables high resolution timer support. If your
	116	hardware is not capable then this option only increases
	117	the size of the kernel image.
	118
	119	endmenu
	120	endif