diff options
Diffstat (limited to 'kernel/time/Kconfig')
| -rw-r--r-- | kernel/time/Kconfig | 159 |
1 files changed, 114 insertions, 45 deletions
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig index 70f27e89012b..7c6a52f7836c 100644 --- a/kernel/time/Kconfig +++ b/kernel/time/Kconfig @@ -1,3 +1,4 @@ +# SPDX-License-Identifier: GPL-2.0-only # # Timer subsystem related configuration options # @@ -12,31 +13,17 @@ config CLOCKSOURCE_WATCHDOG config ARCH_CLOCKSOURCE_DATA bool -# Timekeeping vsyscall support -config GENERIC_TIME_VSYSCALL +# Architecture has extra clocksource init called from registration +config ARCH_CLOCKSOURCE_INIT bool # Timekeeping vsyscall support -config GENERIC_TIME_VSYSCALL_OLD - bool - -# ktime_t scalar 64bit nsec representation -config KTIME_SCALAR - bool - -# Old style timekeeping -config ARCH_USES_GETTIMEOFFSET +config GENERIC_TIME_VSYSCALL bool # The generic clock events infrastructure config GENERIC_CLOCKEVENTS - bool - -# Migration helper. Builds, but does not invoke -config GENERIC_CLOCKEVENTS_BUILD - bool - default y - depends on GENERIC_CLOCKEVENTS + def_bool !LEGACY_TIMER_TICK # Architecture can handle broadcast in a driver-agnostic way config ARCH_HAS_TICK_BROADCAST @@ -47,6 +34,11 @@ config GENERIC_CLOCKEVENTS_BROADCAST bool depends on GENERIC_CLOCKEVENTS +# Handle broadcast in default_idle_call() +config GENERIC_CLOCKEVENTS_BROADCAST_IDLE + bool + depends on GENERIC_CLOCKEVENTS_BROADCAST + # Automatically adjust the min. reprogramming time for # clock event device config GENERIC_CLOCKEVENTS_MIN_ADJUST @@ -56,18 +48,51 @@ config GENERIC_CLOCKEVENTS_MIN_ADJUST config GENERIC_CMOS_UPDATE bool -if GENERIC_CLOCKEVENTS +# 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. + +config CONTEXT_TRACKING + bool + +config CONTEXT_TRACKING_IDLE + bool + select CONTEXT_TRACKING + help + Tracks idle state on behalf of RCU. + menu "Timers subsystem" +if GENERIC_CLOCKEVENTS # Core internal switch. Selected by NO_HZ_COMMON / HIGH_RES_TIMERS. This is # only related to the tick functionality. Oneshot clockevent devices -# are supported independ of this. +# are supported independent of this. config TICK_ONESHOT bool config NO_HZ_COMMON bool - depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS select TICK_ONESHOT choice @@ -82,7 +107,6 @@ config HZ_PERIODIC config NO_HZ_IDLE bool "Idle dynticks system (tickless idle)" - depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS select NO_HZ_COMMON help This option enables a tickless idle system: timer interrupts @@ -94,19 +118,16 @@ config NO_HZ_IDLE config NO_HZ_FULL bool "Full dynticks system (tickless)" # NO_HZ_COMMON dependency - depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS # We need at least one periodic CPU for timekeeping depends on SMP - # RCU_USER_QS dependency - depends on HAVE_CONTEXT_TRACKING + depends on HAVE_CONTEXT_TRACKING_USER # VIRT_CPU_ACCOUNTING_GEN dependency - depends on 64BIT + depends on HAVE_VIRT_CPU_ACCOUNTING_GEN select NO_HZ_COMMON - select RCU_USER_QS select RCU_NOCB_CPU select VIRT_CPU_ACCOUNTING_GEN - select CONTEXT_TRACKING_FORCE 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 @@ -114,29 +135,54 @@ config NO_HZ_FULL 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. + 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. - This is implemented at the expense of some overhead in user <-> kernel - transitions: syscalls, exceptions and interrupts. Even when it's - dynamically off. + By default, without passing the nohz_full parameter, this behaves just + like NO_HZ_IDLE. - Say N. + If you're a distro say Y. endchoice -config NO_HZ_FULL_ALL - bool "Full dynticks system on all CPUs by default" - depends on NO_HZ_FULL - help - If the user doesn't pass the nohz_full boot option to - define the range of full dynticks CPUs, consider that all - CPUs in the system are full dynticks by default. - Note the boot CPU will still be kept outside the range to - handle the timekeeping duty. +config CONTEXT_TRACKING_USER + bool + depends on HAVE_CONTEXT_TRACKING_USER + select CONTEXT_TRACKING + help + Track transitions between kernel and user on behalf of RCU and + tickless cputime accounting. The former case relies on context + tracking to enter/exit RCU extended quiescent states. + +config CONTEXT_TRACKING_USER_FORCE + bool "Force user context tracking" + depends on CONTEXT_TRACKING_USER + default y if !NO_HZ_FULL + help + The major pre-requirement for full dynticks to work is to + support the user 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 + user 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 user 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 user context tracking on all + CPUs in the system. + + Say Y only if you're working on the development of an + architecture backend for the user 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" - depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS help This is the old config entry that enables dynticks idle. We keep it around for a little while to enforce backward @@ -144,12 +190,35 @@ config NO_HZ config HIGH_RES_TIMERS bool "High Resolution Timer Support" - depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS 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 +config CLOCKSOURCE_WATCHDOG_MAX_SKEW_US + int "Clocksource watchdog maximum allowable skew (in microseconds)" + depends on CLOCKSOURCE_WATCHDOG + range 50 1000 + default 125 + help + Specify the maximum amount of allowable watchdog skew in + microseconds before reporting the clocksource to be unstable. + The default is based on a half-second clocksource watchdog + interval and NTP's maximum frequency drift of 500 parts + per million. If the clocksource is good enough for NTP, + it is good enough for the clocksource watchdog! endif + +config POSIX_AUX_CLOCKS + bool "Enable auxiliary POSIX clocks" + depends on POSIX_TIMERS + help + Auxiliary POSIX clocks are clocks which can be steered + independently of the core timekeeper, which controls the + MONOTONIC, REALTIME, BOOTTIME and TAI clocks. They are useful to + provide e.g. lockless time accessors to independent PTP clocks + and other clock domains, which are not correlated to the TAI/NTP + notion of time. + +endmenu |