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Add a new option CONFIG_SCHED_TICKLESS to enable the tickless OS. This is a work in progress but should be relatively safe since the new features are only enabled by this option (Safer but not 100% safe since it does not protect from typos and other dumb errors).

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This commit is contained in:
Gregory Nutt 2014-08-06 18:25:42 -06:00
parent e1f9786db8
commit f0eb4235d1
1 changed files with 26 additions and 1 deletions
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27
sched/Kconfig
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@ -53,14 +53,37 @@ endif # DISABLE_OS_API
menu "Clocks and Timers" menu "Clocks and Timers"
config SCHED_TICKLESS
bool "Support tick-less OS"
default n
depends on EXPERIMENTAL
---help---
Be default, system time is driven by a periodic timer interrupt. An
alternative configurations is a tick-less configuration in which
there is no periodic timer interrupt. Instead and interval timer is
used to schedule the next OS time event. This option selects that
tick-less OS option. If the tick-less OS is selected, then there are
additional plaform specific interfaces that must be provided as
defined include/nuttx/arch.h
config MSEC_PER_TICK config MSEC_PER_TICK
int "Milliseconds per system timer tick" int "Milliseconds per system timer tick"
default 10 default 10 if !SCHED_TICKLESS
default 1 if SCHED_TICKLESS
---help--- ---help---
The default system timer is 100Hz or MSEC_PER_TICK=10. This setting The default system timer is 100Hz or MSEC_PER_TICK=10. This setting
may be defined to inform NuttX that the processor hardware is providing may be defined to inform NuttX that the processor hardware is providing
system timer interrupts at some interrupt interval other than 10 msec. system timer interrupts at some interrupt interval other than 10 msec.
If SCHED_TICKLESS is selected, then there are no system timer
interrupts. In this case, MSEC_PER_TICK does not control any timer
rates. Rather, it only determines the resolution of time reported
by clock_systimer() and the resolution of times that can be set for
certain delays including watchdog timers and delayed work. In these
cases it is better to have the MSEC_PER_TICK as low as possible.
if !SCHED_TICKLESS
config SYSTEMTICK_EXTCLK config SYSTEMTICK_EXTCLK
bool "Use external clock" bool "Use external clock"
default n default n
@ -72,6 +95,8 @@ config SYSTEMTICK_EXTCLK
to move the scheduling off the processor clock to allow entering low to move the scheduling off the processor clock to allow entering low
power states that would disable that clock. power states that would disable that clock.
endif # !SCHED_TICKLESS
config SYSTEM_TIME64 config SYSTEM_TIME64
bool "64-bit system clock" bool "64-bit system clock"
default n default n