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Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001#
2# Timer subsystem related configuration options
3#
Thomas Gleixner3872c482012-03-31 12:45:43 +02004
Thomas Gleixnerb5e498a2012-05-18 09:59:57 +02005# Options selectable by arch Kconfig
6
7# Watchdog function for clocksources to detect instabilities
8config CLOCKSOURCE_WATCHDOG
9 bool
10
11# Architecture has extra clocksource data
12config ARCH_CLOCKSOURCE_DATA
13 bool
14
15# Timekeeping vsyscall support
John Stultz576094b2012-09-11 19:58:13 -040016config GENERIC_TIME_VSYSCALL
17 bool
18
19# Timekeeping vsyscall support
John Stultz70639422012-09-04 15:34:21 -040020config GENERIC_TIME_VSYSCALL_OLD
Thomas Gleixnerb5e498a2012-05-18 09:59:57 +020021 bool
22
23# ktime_t scalar 64bit nsec representation
24config KTIME_SCALAR
25 bool
26
27# Old style timekeeping
28config ARCH_USES_GETTIMEOFFSET
29 bool
30
31# The generic clock events infrastructure
32config GENERIC_CLOCKEVENTS
33 bool
34
Thomas Gleixner764e0da2012-05-21 23:16:18 +020035# Migration helper. Builds, but does not invoke
36config GENERIC_CLOCKEVENTS_BUILD
37 bool
38 default y
39 depends on GENERIC_CLOCKEVENTS
40
Mark Rutland12ad1002013-01-14 17:05:22 +000041# Architecture can handle broadcast in a driver-agnostic way
42config ARCH_HAS_TICK_BROADCAST
43 bool
44
Thomas Gleixnerb5e498a2012-05-18 09:59:57 +020045# Clockevents broadcasting infrastructure
46config GENERIC_CLOCKEVENTS_BROADCAST
47 bool
48 depends on GENERIC_CLOCKEVENTS
49
Thomas Gleixner764e0da2012-05-21 23:16:18 +020050# Automatically adjust the min. reprogramming time for
51# clock event device
52config GENERIC_CLOCKEVENTS_MIN_ADJUST
53 bool
54
Thomas Gleixnerb5e498a2012-05-18 09:59:57 +020055# Generic update of CMOS clock
56config GENERIC_CMOS_UPDATE
57 bool
Thomas Gleixner764e0da2012-05-21 23:16:18 +020058
59if GENERIC_CLOCKEVENTS
60menu "Timers subsystem"
61
Frederic Weisbecker3451d022011-08-10 23:21:01 +020062# Core internal switch. Selected by NO_HZ_COMMON / HIGH_RES_TIMERS. This is
Thomas Gleixner764e0da2012-05-21 23:16:18 +020063# only related to the tick functionality. Oneshot clockevent devices
64# are supported independ of this.
65config TICK_ONESHOT
66 bool
67
Frederic Weisbecker3451d022011-08-10 23:21:01 +020068config NO_HZ_COMMON
69 bool
70 depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
71 select TICK_ONESHOT
72
Frederic Weisbecker3ca277e2011-08-10 23:21:01 +020073choice
74 prompt "Timer tick handling"
75 default NO_HZ_IDLE if NO_HZ
76
Frederic Weisbecker5b533f42013-04-13 16:53:35 +020077config HZ_PERIODIC
Frederic Weisbecker3ca277e2011-08-10 23:21:01 +020078 bool "Periodic timer ticks (constant rate, no dynticks)"
79 help
80 This option keeps the tick running periodically at a constant
81 rate, even when the CPU doesn't need it.
82
83config NO_HZ_IDLE
84 bool "Idle dynticks system (tickless idle)"
Thomas Gleixner764e0da2012-05-21 23:16:18 +020085 depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
Frederic Weisbecker3451d022011-08-10 23:21:01 +020086 select NO_HZ_COMMON
Thomas Gleixner764e0da2012-05-21 23:16:18 +020087 help
Frederic Weisbecker3ca277e2011-08-10 23:21:01 +020088 This option enables a tickless idle system: timer interrupts
89 will only trigger on an as-needed basis when the system is idle.
90 This is usually interesting for energy saving.
91
92 Most of the time you want to say Y here.
Thomas Gleixner764e0da2012-05-21 23:16:18 +020093
Frederic Weisbeckerc5bfece2013-04-12 16:45:34 +020094config NO_HZ_FULL
Frederic Weisbeckerfae30dd2013-04-13 17:04:04 +020095 bool "Full dynticks system (tickless)"
Frederic Weisbecker3451d022011-08-10 23:21:01 +020096 # NO_HZ_COMMON dependency
Frederic Weisbeckerab71d362011-08-10 23:21:01 +020097 depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
Frederic Weisbeckerfae30dd2013-04-13 17:04:04 +020098 # We need at least one periodic CPU for timekeeping
99 depends on SMP
100 # RCU_USER_QS dependency
101 depends on HAVE_CONTEXT_TRACKING
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200102 # VIRT_CPU_ACCOUNTING_GEN dependency
103 depends on 64BIT
Frederic Weisbecker3451d022011-08-10 23:21:01 +0200104 select NO_HZ_COMMON
Frederic Weisbeckerab71d362011-08-10 23:21:01 +0200105 select RCU_USER_QS
106 select RCU_NOCB_CPU
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200107 select VIRT_CPU_ACCOUNTING_GEN
Frederic Weisbeckerab71d362011-08-10 23:21:01 +0200108 select CONTEXT_TRACKING_FORCE
Frederic Weisbecker76c24fb2013-04-18 00:15:40 +0200109 select IRQ_WORK
Frederic Weisbeckerab71d362011-08-10 23:21:01 +0200110 help
111 Adaptively try to shutdown the tick whenever possible, even when
Frederic Weisbeckera8318812012-12-18 17:32:19 +0100112 the CPU is running tasks. Typically this requires running a single
113 task on the CPU. Chances for running tickless are maximized when
114 the task mostly runs in userspace and has few kernel activity.
115
Frederic Weisbeckerc5bfece2013-04-12 16:45:34 +0200116 You need to fill up the nohz_full boot parameter with the
Frederic Weisbeckera8318812012-12-18 17:32:19 +0100117 desired range of dynticks CPUs.
118
119 This is implemented at the expense of some overhead in user <-> kernel
120 transitions: syscalls, exceptions and interrupts. Even when it's
121 dynamically off.
122
123 Say N.
124
Frederic Weisbecker3ca277e2011-08-10 23:21:01 +0200125endchoice
126
Frederic Weisbeckerf98823a2013-03-27 01:17:22 +0100127config NO_HZ_FULL_ALL
128 bool "Full dynticks system on all CPUs by default"
129 depends on NO_HZ_FULL
130 help
131 If the user doesn't pass the nohz_full boot option to
132 define the range of full dynticks CPUs, consider that all
133 CPUs in the system are full dynticks by default.
134 Note the boot CPU will still be kept outside the range to
135 handle the timekeeping duty.
136
Frederic Weisbecker0644ca52013-04-12 16:40:12 +0200137config NO_HZ
138 bool "Old Idle dynticks config"
139 depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
140 help
141 This is the old config entry that enables dynticks idle.
142 We keep it around for a little while to enforce backward
143 compatibility with older config files.
144
Thomas Gleixner764e0da2012-05-21 23:16:18 +0200145config HIGH_RES_TIMERS
146 bool "High Resolution Timer Support"
147 depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
148 select TICK_ONESHOT
149 help
150 This option enables high resolution timer support. If your
151 hardware is not capable then this option only increases
152 the size of the kernel image.
153
154endmenu
155endif