projects/linux·blob v4.13 · refs

147 lines · 4.0 KiB

1#
2# Timer subsystem related configuration options
3#
4
5# 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# Clocksources require validation of the clocksource against the last
16# cycle update - x86/TSC misfeature
17config CLOCKSOURCE_VALIDATE_LAST_CYCLE
18 bool
19
20# Timekeeping vsyscall support
21config GENERIC_TIME_VSYSCALL
22 bool
23
24# Timekeeping vsyscall support
25config GENERIC_TIME_VSYSCALL_OLD
26 bool
27
28# Old style timekeeping
29config ARCH_USES_GETTIMEOFFSET
30 bool
31
32# The generic clock events infrastructure
33config GENERIC_CLOCKEVENTS
34 bool
35
36# Architecture can handle broadcast in a driver-agnostic way
37config ARCH_HAS_TICK_BROADCAST
38 bool
39
40# Clockevents broadcasting infrastructure
41config GENERIC_CLOCKEVENTS_BROADCAST
42 bool
43 depends on GENERIC_CLOCKEVENTS
44
45# Automatically adjust the min. reprogramming time for
46# clock event device
47config GENERIC_CLOCKEVENTS_MIN_ADJUST
48 bool
49
50# Generic update of CMOS clock
51config GENERIC_CMOS_UPDATE
52 bool
53
54if GENERIC_CLOCKEVENTS
55menu "Timers subsystem"
56
57# Core internal switch. Selected by NO_HZ_COMMON / HIGH_RES_TIMERS. This is
58# only related to the tick functionality. Oneshot clockevent devices
59# are supported independ of this.
60config TICK_ONESHOT
61 bool
62
63config NO_HZ_COMMON
64 bool
65 depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
66 select TICK_ONESHOT
67
68choice
69 prompt "Timer tick handling"
70 default NO_HZ_IDLE if NO_HZ
71
72config HZ_PERIODIC
73 bool "Periodic timer ticks (constant rate, no dynticks)"
74 help
75 This option keeps the tick running periodically at a constant
76 rate, even when the CPU doesn't need it.
77
78config NO_HZ_IDLE
79 bool "Idle dynticks system (tickless idle)"
80 depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
81 select NO_HZ_COMMON
82 help
83 This option enables a tickless idle system: timer interrupts
84 will only trigger on an as-needed basis when the system is idle.
85 This is usually interesting for energy saving.
86
87 Most of the time you want to say Y here.
88
89config NO_HZ_FULL
90 bool "Full dynticks system (tickless)"
91 # NO_HZ_COMMON dependency
92 depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
93 # We need at least one periodic CPU for timekeeping
94 depends on SMP
95 depends on HAVE_CONTEXT_TRACKING
96 # VIRT_CPU_ACCOUNTING_GEN dependency
97 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
98 select NO_HZ_COMMON
99 select RCU_NOCB_CPU
100 select VIRT_CPU_ACCOUNTING_GEN
101 select IRQ_WORK
102 help
103 Adaptively try to shutdown the tick whenever possible, even when
104 the CPU is running tasks. Typically this requires running a single
105 task on the CPU. Chances for running tickless are maximized when
106 the task mostly runs in userspace and has few kernel activity.
107
108 You need to fill up the nohz_full boot parameter with the
109 desired range of dynticks CPUs.
110
111 This is implemented at the expense of some overhead in user <-> kernel
112 transitions: syscalls, exceptions and interrupts. Even when it's
113 dynamically off.
114
115 Say N.
116
117endchoice
118
119config NO_HZ_FULL_ALL
120 bool "Full dynticks system on all CPUs by default (except CPU 0)"
121 depends on NO_HZ_FULL
122 help
123 If the user doesn't pass the nohz_full boot option to
124 define the range of full dynticks CPUs, consider that all
125 CPUs in the system are full dynticks by default.
126 Note the boot CPU will still be kept outside the range to
127 handle the timekeeping duty.
128
129config NO_HZ
130 bool "Old Idle dynticks config"
131 depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
132 help
133 This is the old config entry that enables dynticks idle.
134 We keep it around for a little while to enforce backward
135 compatibility with older config files.
136
137config HIGH_RES_TIMERS
138 bool "High Resolution Timer Support"
139 depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
140 select TICK_ONESHOT
141 help
142 This option enables high resolution timer support. If your
143 hardware is not capable then this option only increases
144 the size of the kernel image.
145
146endmenu
147endif