186 lines
5.1 KiB
Plaintext
186 lines
5.1 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
|
|
#
|
|
# Timer subsystem related configuration options
|
|
#
|
|
|
|
# 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
|
|
|
|
# Architecture has extra clocksource init called from registration
|
|
config ARCH_CLOCKSOURCE_INIT
|
|
bool
|
|
|
|
# Clocksources require validation of the clocksource against the last
|
|
# cycle update - x86/TSC misfeature
|
|
config CLOCKSOURCE_VALIDATE_LAST_CYCLE
|
|
bool
|
|
|
|
# Timekeeping vsyscall support
|
|
config GENERIC_TIME_VSYSCALL
|
|
bool
|
|
|
|
# The generic clock events infrastructure
|
|
config GENERIC_CLOCKEVENTS
|
|
def_bool !LEGACY_TIMER_TICK
|
|
|
|
# Architecture can handle broadcast in a driver-agnostic way
|
|
config ARCH_HAS_TICK_BROADCAST
|
|
bool
|
|
|
|
# Clockevents broadcasting infrastructure
|
|
config GENERIC_CLOCKEVENTS_BROADCAST
|
|
bool
|
|
depends on GENERIC_CLOCKEVENTS
|
|
|
|
# Automatically adjust the min. reprogramming time for
|
|
# clock event device
|
|
config GENERIC_CLOCKEVENTS_MIN_ADJUST
|
|
bool
|
|
|
|
# Generic update of CMOS clock
|
|
config GENERIC_CMOS_UPDATE
|
|
bool
|
|
|
|
# Select to handle posix CPU timers from task_work
|
|
# and not from the timer interrupt context
|
|
config HAVE_POSIX_CPU_TIMERS_TASK_WORK
|
|
bool
|
|
|
|
config POSIX_CPU_TIMERS_TASK_WORK
|
|
bool
|
|
default y if POSIX_TIMERS && HAVE_POSIX_CPU_TIMERS_TASK_WORK
|
|
|
|
config LEGACY_TIMER_TICK
|
|
bool
|
|
help
|
|
The legacy timer tick helper is used by platforms that
|
|
lack support for the generic clockevent framework.
|
|
New platforms should use generic clockevents instead.
|
|
|
|
config TIME_KUNIT_TEST
|
|
tristate "KUnit test for kernel/time functions" if !KUNIT_ALL_TESTS
|
|
depends on KUNIT
|
|
default KUNIT_ALL_TESTS
|
|
help
|
|
Enable this option to test RTC library functions.
|
|
|
|
If unsure, say N.
|
|
|
|
if GENERIC_CLOCKEVENTS
|
|
menu "Timers subsystem"
|
|
|
|
# Core internal switch. Selected by NO_HZ_COMMON / HIGH_RES_TIMERS. This is
|
|
# only related to the tick functionality. Oneshot clockevent devices
|
|
# are supported independent of this.
|
|
config TICK_ONESHOT
|
|
bool
|
|
|
|
config NO_HZ_COMMON
|
|
bool
|
|
select TICK_ONESHOT
|
|
|
|
choice
|
|
prompt "Timer tick handling"
|
|
default NO_HZ_IDLE if NO_HZ
|
|
|
|
config HZ_PERIODIC
|
|
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)"
|
|
select NO_HZ_COMMON
|
|
help
|
|
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.
|
|
|
|
config NO_HZ_FULL
|
|
bool "Full dynticks system (tickless)"
|
|
# NO_HZ_COMMON dependency
|
|
# We need at least one periodic CPU for timekeeping
|
|
depends on SMP
|
|
depends on HAVE_CONTEXT_TRACKING
|
|
# VIRT_CPU_ACCOUNTING_GEN dependency
|
|
depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
|
|
select NO_HZ_COMMON
|
|
select RCU_NOCB_CPU
|
|
select VIRT_CPU_ACCOUNTING_GEN
|
|
select IRQ_WORK
|
|
select CPU_ISOLATION
|
|
help
|
|
Adaptively try to shutdown the tick whenever possible, even when
|
|
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.
|
|
|
|
You need to fill up the nohz_full boot parameter with the
|
|
desired range of dynticks CPUs to use it. This is implemented at
|
|
the expense of some overhead in user <-> kernel transitions:
|
|
syscalls, exceptions and interrupts.
|
|
|
|
By default, without passing the nohz_full parameter, this behaves just
|
|
like NO_HZ_IDLE.
|
|
|
|
If you're a distro say Y.
|
|
|
|
endchoice
|
|
|
|
config CONTEXT_TRACKING
|
|
bool
|
|
|
|
config CONTEXT_TRACKING_FORCE
|
|
bool "Force context tracking"
|
|
depends on CONTEXT_TRACKING
|
|
default y if !NO_HZ_FULL
|
|
help
|
|
The major pre-requirement for full dynticks to work is to
|
|
support the context tracking subsystem. But there are also
|
|
other dependencies to provide in order to make the full
|
|
dynticks working.
|
|
|
|
This option stands for testing when an arch implements the
|
|
context tracking backend but doesn't yet fulfill all the
|
|
requirements to make the full dynticks feature working.
|
|
Without the full dynticks, there is no way to test the support
|
|
for context tracking and the subsystems that rely on it: RCU
|
|
userspace extended quiescent state and tickless cputime
|
|
accounting. This option copes with the absence of the full
|
|
dynticks subsystem by forcing the context tracking on all
|
|
CPUs in the system.
|
|
|
|
Say Y only if you're working on the development of an
|
|
architecture backend for the context tracking.
|
|
|
|
Say N otherwise, this option brings an overhead that you
|
|
don't want in production.
|
|
|
|
config NO_HZ
|
|
bool "Old Idle dynticks config"
|
|
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.
|
|
|
|
config HIGH_RES_TIMERS
|
|
bool "High Resolution Timer Support"
|
|
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
|