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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 | # The generic clock events infrastructure |
30 | config GENERIC_CLOCKEVENTS | |
31 | bool | |
32 | ||
12ad1000 MR |
33 | # Architecture can handle broadcast in a driver-agnostic way |
34 | config ARCH_HAS_TICK_BROADCAST | |
35 | bool | |
36 | ||
b5e498ad TG |
37 | # Clockevents broadcasting infrastructure |
38 | config GENERIC_CLOCKEVENTS_BROADCAST | |
39 | bool | |
40 | depends on GENERIC_CLOCKEVENTS | |
41 | ||
764e0da1 TG |
42 | # Automatically adjust the min. reprogramming time for |
43 | # clock event device | |
44 | config GENERIC_CLOCKEVENTS_MIN_ADJUST | |
45 | bool | |
46 | ||
b5e498ad TG |
47 | # Generic update of CMOS clock |
48 | config GENERIC_CMOS_UPDATE | |
49 | bool | |
764e0da1 | 50 | |
1fb497dd TG |
51 | # Select to handle posix CPU timers from task_work |
52 | # and not from the timer interrupt context | |
53 | config HAVE_POSIX_CPU_TIMERS_TASK_WORK | |
54 | bool | |
55 | ||
56 | config POSIX_CPU_TIMERS_TASK_WORK | |
57 | bool | |
58 | default y if POSIX_TIMERS && HAVE_POSIX_CPU_TIMERS_TASK_WORK | |
59 | ||
764e0da1 TG |
60 | if GENERIC_CLOCKEVENTS |
61 | menu "Timers subsystem" | |
62 | ||
3451d024 | 63 | # Core internal switch. Selected by NO_HZ_COMMON / HIGH_RES_TIMERS. This is |
764e0da1 | 64 | # only related to the tick functionality. Oneshot clockevent devices |
6082a6e4 | 65 | # are supported independent of this. |
764e0da1 TG |
66 | config TICK_ONESHOT |
67 | bool | |
68 | ||
3451d024 FW |
69 | config NO_HZ_COMMON |
70 | bool | |
3451d024 FW |
71 | select TICK_ONESHOT |
72 | ||
3ca277e4 FW |
73 | choice |
74 | prompt "Timer tick handling" | |
75 | default NO_HZ_IDLE if NO_HZ | |
76 | ||
5b533f4f | 77 | config HZ_PERIODIC |
3ca277e4 FW |
78 | 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 | ||
83 | config NO_HZ_IDLE | |
84 | bool "Idle dynticks system (tickless idle)" | |
3451d024 | 85 | select NO_HZ_COMMON |
764e0da1 | 86 | help |
3ca277e4 FW |
87 | This option enables a tickless idle system: timer interrupts |
88 | will only trigger on an as-needed basis when the system is idle. | |
89 | This is usually interesting for energy saving. | |
90 | ||
91 | Most of the time you want to say Y here. | |
764e0da1 | 92 | |
c5bfece2 | 93 | config NO_HZ_FULL |
fae30dd6 | 94 | bool "Full dynticks system (tickless)" |
3451d024 | 95 | # NO_HZ_COMMON dependency |
fae30dd6 FW |
96 | # We need at least one periodic CPU for timekeeping |
97 | depends on SMP | |
fae30dd6 | 98 | depends on HAVE_CONTEXT_TRACKING |
c58b0df1 | 99 | # VIRT_CPU_ACCOUNTING_GEN dependency |
554b0004 | 100 | depends on HAVE_VIRT_CPU_ACCOUNTING_GEN |
3451d024 | 101 | select NO_HZ_COMMON |
ab71d36d | 102 | select RCU_NOCB_CPU |
c58b0df1 | 103 | select VIRT_CPU_ACCOUNTING_GEN |
76c24fb0 | 104 | select IRQ_WORK |
bf29cb23 | 105 | select CPU_ISOLATION |
ab71d36d FW |
106 | help |
107 | Adaptively try to shutdown the tick whenever possible, even when | |
a831881b FW |
108 | the CPU is running tasks. Typically this requires running a single |
109 | task on the CPU. Chances for running tickless are maximized when | |
110 | the task mostly runs in userspace and has few kernel activity. | |
111 | ||
c5bfece2 | 112 | You need to fill up the nohz_full boot parameter with the |
a831881b FW |
113 | desired range of dynticks CPUs. |
114 | ||
115 | This is implemented at the expense of some overhead in user <-> kernel | |
116 | transitions: syscalls, exceptions and interrupts. Even when it's | |
117 | dynamically off. | |
118 | ||
119 | Say N. | |
120 | ||
3ca277e4 FW |
121 | endchoice |
122 | ||
a4cffdad PM |
123 | config CONTEXT_TRACKING |
124 | bool | |
125 | ||
126 | config CONTEXT_TRACKING_FORCE | |
127 | bool "Force context tracking" | |
128 | depends on CONTEXT_TRACKING | |
129 | default y if !NO_HZ_FULL | |
130 | help | |
131 | The major pre-requirement for full dynticks to work is to | |
132 | support the context tracking subsystem. But there are also | |
133 | other dependencies to provide in order to make the full | |
134 | dynticks working. | |
135 | ||
136 | This option stands for testing when an arch implements the | |
137 | context tracking backend but doesn't yet fullfill all the | |
138 | requirements to make the full dynticks feature working. | |
139 | Without the full dynticks, there is no way to test the support | |
140 | for context tracking and the subsystems that rely on it: RCU | |
141 | userspace extended quiescent state and tickless cputime | |
142 | accounting. This option copes with the absence of the full | |
143 | dynticks subsystem by forcing the context tracking on all | |
144 | CPUs in the system. | |
145 | ||
146 | Say Y only if you're working on the development of an | |
147 | architecture backend for the context tracking. | |
148 | ||
149 | Say N otherwise, this option brings an overhead that you | |
150 | don't want in production. | |
151 | ||
0644ca5c FW |
152 | config NO_HZ |
153 | bool "Old Idle dynticks config" | |
0644ca5c FW |
154 | help |
155 | This is the old config entry that enables dynticks idle. | |
156 | We keep it around for a little while to enforce backward | |
157 | compatibility with older config files. | |
158 | ||
764e0da1 TG |
159 | config HIGH_RES_TIMERS |
160 | bool "High Resolution Timer Support" | |
764e0da1 TG |
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 |