Commit | Line | Data |
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ec8f24b7 | 1 | # SPDX-License-Identifier: GPL-2.0-only |
79bf2bb3 TG |
2 | # |
3 | # Timer subsystem related configuration options | |
4 | # | |
3872c48b | 5 | |
b5e498ad TG |
6 | # Options selectable by arch Kconfig |
7 | ||
8 | # Watchdog function for clocksources to detect instabilities | |
9 | config CLOCKSOURCE_WATCHDOG | |
10 | bool | |
11 | ||
12 | # Architecture has extra clocksource data | |
13 | config ARCH_CLOCKSOURCE_DATA | |
14 | bool | |
15 | ||
d67f34c1 TG |
16 | # Architecture has extra clocksource init called from registration |
17 | config ARCH_CLOCKSOURCE_INIT | |
18 | bool | |
19 | ||
09ec5442 TG |
20 | # Clocksources require validation of the clocksource against the last |
21 | # cycle update - x86/TSC misfeature | |
22 | config CLOCKSOURCE_VALIDATE_LAST_CYCLE | |
23 | bool | |
24 | ||
576094b7 JS |
25 | # Timekeeping vsyscall support |
26 | config GENERIC_TIME_VSYSCALL | |
27 | bool | |
28 | ||
b5e498ad TG |
29 | # Old style timekeeping |
30 | config ARCH_USES_GETTIMEOFFSET | |
31 | bool | |
32 | ||
33 | # The generic clock events infrastructure | |
34 | config GENERIC_CLOCKEVENTS | |
35 | bool | |
36 | ||
12ad1000 MR |
37 | # Architecture can handle broadcast in a driver-agnostic way |
38 | config ARCH_HAS_TICK_BROADCAST | |
39 | bool | |
40 | ||
b5e498ad TG |
41 | # Clockevents broadcasting infrastructure |
42 | config GENERIC_CLOCKEVENTS_BROADCAST | |
43 | bool | |
44 | depends on GENERIC_CLOCKEVENTS | |
45 | ||
764e0da1 TG |
46 | # Automatically adjust the min. reprogramming time for |
47 | # clock event device | |
48 | config GENERIC_CLOCKEVENTS_MIN_ADJUST | |
49 | bool | |
50 | ||
b5e498ad TG |
51 | # Generic update of CMOS clock |
52 | config GENERIC_CMOS_UPDATE | |
53 | bool | |
764e0da1 TG |
54 | |
55 | if GENERIC_CLOCKEVENTS | |
56 | menu "Timers subsystem" | |
57 | ||
3451d024 | 58 | # Core internal switch. Selected by NO_HZ_COMMON / HIGH_RES_TIMERS. This is |
764e0da1 | 59 | # only related to the tick functionality. Oneshot clockevent devices |
6082a6e4 | 60 | # are supported independent of this. |
764e0da1 TG |
61 | config TICK_ONESHOT |
62 | bool | |
63 | ||
3451d024 FW |
64 | config NO_HZ_COMMON |
65 | bool | |
66 | depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS | |
67 | select TICK_ONESHOT | |
68 | ||
3ca277e4 FW |
69 | choice |
70 | prompt "Timer tick handling" | |
71 | default NO_HZ_IDLE if NO_HZ | |
72 | ||
5b533f4f | 73 | config HZ_PERIODIC |
3ca277e4 FW |
74 | bool "Periodic timer ticks (constant rate, no dynticks)" |
75 | help | |
76 | This option keeps the tick running periodically at a constant | |
77 | rate, even when the CPU doesn't need it. | |
78 | ||
79 | config NO_HZ_IDLE | |
80 | bool "Idle dynticks system (tickless idle)" | |
764e0da1 | 81 | depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS |
3451d024 | 82 | select NO_HZ_COMMON |
764e0da1 | 83 | help |
3ca277e4 FW |
84 | This option enables a tickless idle system: timer interrupts |
85 | will only trigger on an as-needed basis when the system is idle. | |
86 | This is usually interesting for energy saving. | |
87 | ||
88 | Most of the time you want to say Y here. | |
764e0da1 | 89 | |
c5bfece2 | 90 | config NO_HZ_FULL |
fae30dd6 | 91 | bool "Full dynticks system (tickless)" |
3451d024 | 92 | # NO_HZ_COMMON dependency |
ab71d36d | 93 | depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS |
fae30dd6 FW |
94 | # We need at least one periodic CPU for timekeeping |
95 | depends on SMP | |
fae30dd6 | 96 | depends on HAVE_CONTEXT_TRACKING |
c58b0df1 | 97 | # VIRT_CPU_ACCOUNTING_GEN dependency |
554b0004 | 98 | depends on HAVE_VIRT_CPU_ACCOUNTING_GEN |
3451d024 | 99 | select NO_HZ_COMMON |
ab71d36d | 100 | select RCU_NOCB_CPU |
c58b0df1 | 101 | select VIRT_CPU_ACCOUNTING_GEN |
76c24fb0 | 102 | select IRQ_WORK |
bf29cb23 | 103 | select CPU_ISOLATION |
ab71d36d FW |
104 | help |
105 | Adaptively try to shutdown the tick whenever possible, even when | |
a831881b FW |
106 | the CPU is running tasks. Typically this requires running a single |
107 | task on the CPU. Chances for running tickless are maximized when | |
108 | the task mostly runs in userspace and has few kernel activity. | |
109 | ||
c5bfece2 | 110 | You need to fill up the nohz_full boot parameter with the |
a831881b FW |
111 | desired range of dynticks CPUs. |
112 | ||
113 | This is implemented at the expense of some overhead in user <-> kernel | |
114 | transitions: syscalls, exceptions and interrupts. Even when it's | |
115 | dynamically off. | |
116 | ||
117 | Say N. | |
118 | ||
3ca277e4 FW |
119 | endchoice |
120 | ||
a4cffdad PM |
121 | config CONTEXT_TRACKING |
122 | bool | |
123 | ||
124 | config CONTEXT_TRACKING_FORCE | |
125 | bool "Force context tracking" | |
126 | depends on CONTEXT_TRACKING | |
127 | default y if !NO_HZ_FULL | |
128 | help | |
129 | The major pre-requirement for full dynticks to work is to | |
130 | support the context tracking subsystem. But there are also | |
131 | other dependencies to provide in order to make the full | |
132 | dynticks working. | |
133 | ||
134 | This option stands for testing when an arch implements the | |
135 | context tracking backend but doesn't yet fullfill all the | |
136 | requirements to make the full dynticks feature working. | |
137 | Without the full dynticks, there is no way to test the support | |
138 | for context tracking and the subsystems that rely on it: RCU | |
139 | userspace extended quiescent state and tickless cputime | |
140 | accounting. This option copes with the absence of the full | |
141 | dynticks subsystem by forcing the context tracking on all | |
142 | CPUs in the system. | |
143 | ||
144 | Say Y only if you're working on the development of an | |
145 | architecture backend for the context tracking. | |
146 | ||
147 | Say N otherwise, this option brings an overhead that you | |
148 | don't want in production. | |
149 | ||
0644ca5c FW |
150 | config NO_HZ |
151 | bool "Old Idle dynticks config" | |
152 | depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS | |
153 | help | |
154 | This is the old config entry that enables dynticks idle. | |
155 | We keep it around for a little while to enforce backward | |
156 | compatibility with older config files. | |
157 | ||
764e0da1 TG |
158 | config HIGH_RES_TIMERS |
159 | bool "High Resolution Timer Support" | |
160 | depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS | |
161 | select TICK_ONESHOT | |
162 | help | |
163 | This option enables high resolution timer support. If your | |
164 | hardware is not capable then this option only increases | |
165 | the size of the kernel image. | |
166 | ||
167 | endmenu | |
168 | endif |