Kconfig 3.7 KB
Newer Older
1 2 3
#
# Timer subsystem related configuration options
#
4

5 6 7 8 9 10 11 12 13 14
# 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

15
# Platforms has a persistent clock
16
config ALWAYS_USE_PERSISTENT_CLOCK
17 18 19
	bool
	default n

20 21 22 23
# Timekeeping vsyscall support
config GENERIC_TIME_VSYSCALL
	bool

24
# Timekeeping vsyscall support
25
config GENERIC_TIME_VSYSCALL_OLD
26 27 28 29 30 31 32 33 34 35 36 37 38 39
	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

40 41 42 43 44 45
# Migration helper. Builds, but does not invoke
config GENERIC_CLOCKEVENTS_BUILD
	bool
	default y
	depends on GENERIC_CLOCKEVENTS

46 47 48 49
# Architecture can handle broadcast in a driver-agnostic way
config ARCH_HAS_TICK_BROADCAST
	bool

50 51 52 53 54
# Clockevents broadcasting infrastructure
config GENERIC_CLOCKEVENTS_BROADCAST
	bool
	depends on GENERIC_CLOCKEVENTS

55 56 57 58 59
# Automatically adjust the min. reprogramming time for
# clock event device
config GENERIC_CLOCKEVENTS_MIN_ADJUST
	bool

60 61 62
# Generic update of CMOS clock
config GENERIC_CMOS_UPDATE
	bool
63 64 65 66

if GENERIC_CLOCKEVENTS
menu "Timers subsystem"

67
# Core internal switch. Selected by NO_HZ_COMMON / HIGH_RES_TIMERS. This is
68 69 70 71 72
# only related to the tick functionality. Oneshot clockevent devices
# are supported independ of this.
config TICK_ONESHOT
	bool

73 74 75 76 77
config NO_HZ_COMMON
	bool
	depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
	select TICK_ONESHOT

78 79 80 81 82 83 84 85 86 87 88 89
choice
	prompt "Timer tick handling"
	default NO_HZ_IDLE if NO_HZ

config PERIODIC_HZ
	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)"
90
	depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
91
	select NO_HZ_COMMON
92
	help
93 94 95 96 97
	  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.
98

99
config NO_HZ_FULL
100
	bool "Full dynticks system (tickless single task)"
101
	# NO_HZ_COMMON dependency
102 103 104 105 106 107
	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
108
	select NO_HZ_COMMON
109 110 111 112 113
	select RCU_USER_QS
	select RCU_NOCB_CPU
	select CONTEXT_TRACKING_FORCE
	help
	 Adaptively try to shutdown the tick whenever possible, even when
114 115 116 117
	 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.

118
	 You need to fill up the nohz_full boot parameter with the
119 120 121 122 123 124 125 126
	 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.

127 128
endchoice

129 130 131 132 133 134 135 136
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.

137 138 139 140 141 142 143 144 145 146 147
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