89ffd44dfb
Adds event based scheduling logic to the kernel. Updates management of timeouts, timers, idling etc. based on time tracked at events rather than periodic ticks. Provides interfaces for timers to announce and get next timer expiry based on kernel scheduling decisions involving time slicing of threads, timeouts and idling. Uses wall time units instead of ticks in all scheduling activities. The implementation involves changes in the following areas 1. Management of time in wall units like ms/us instead of ticks The existing implementation already had an option to configure number of ticks in a second. The new implementation builds on top of that feature and provides option to set the size of the scheduling granurality to mili seconds or micro seconds. This allows most of the current implementation to be reused. Due to this re-use and co-existence with tick based kernel, the names of variables may contain the word "tick". However, in the tickless kernel implementation, it represents the currently configured time unit, which would be be mili seconds or micro seconds. The APIs that take time as a parameter are not impacted and they continue to pass time in mili seconds. 2. Timers would not be programmed in periodic mode generating ticks. Instead they would be programmed in one shot mode to generate events at the time the kernel scheduler needs to gain control for its scheduling activities like timers, timeouts, time slicing, idling etc. 3. The scheduler provides interfaces that the timer drivers use to announce elapsed time and get the next time the scheduler needs a timer event. It is possible that the scheduler may not need another timer event, in which case the system would wait for a non-timer event to wake it up if it is idling. 4. New APIs are defined to be implemented by timer drivers. Also they need to handler timer events differently. These changes have been done in the HPET timer driver. In future other timers that support tickles kernel should implement these APIs as well. These APIs are to re-program the timer, update and announce elapsed time. 5. Philosopher and timer_api applications have been enabled to test tickless kernel. Separate configuration files are created which define the necessary CONFIG flags. Run these apps using following command make pristine && make BOARD=qemu_x86 CONF_FILE=prj_tickless.conf qemu Jira: ZEP-339 ZEP-1946 ZEP-948 Change-Id: I7d950c31bf1ff929a9066fad42c2f0559a2e5983 Signed-off-by: Ramesh Thomas <ramesh.thomas@intel.com>
92 lines
2.1 KiB
C
92 lines
2.1 KiB
C
/*
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* Copyright (c) 2015 Wind River Systems, Inc.
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/**
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* @file
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* @brief Timer driver API
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*
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*
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* Declare API implemented by system timer driver and used by kernel components.
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*/
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#ifndef _TIMER__H_
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#define _TIMER__H_
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifdef _ASMLANGUAGE
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GTEXT(_timer_int_handler)
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#else /* _ASMLANGUAGE */
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#include <device.h>
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extern int _sys_clock_driver_init(struct device *device);
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extern void _timer_int_handler(void *arg);
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#ifdef CONFIG_SYSTEM_CLOCK_DISABLE
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extern void sys_clock_disable(void);
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#endif
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#ifdef CONFIG_TICKLESS_IDLE
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extern void _timer_idle_enter(s32_t ticks);
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extern void _timer_idle_exit(void);
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#else
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#define _timer_idle_enter(ticks) do { } while ((0))
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#define _timer_idle_exit() do { } while ((0))
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#endif /* CONFIG_TICKLESS_IDLE */
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extern void _nano_sys_clock_tick_announce(s32_t ticks);
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#ifdef CONFIG_TICKLESS_KERNEL
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extern void _set_time(u32_t time);
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extern u32_t _get_program_time(void);
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extern u32_t _get_remaining_program_time(void);
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extern u32_t _get_elapsed_program_time(void);
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extern u64_t _get_elapsed_clock_time(void);
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#endif
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extern int sys_clock_device_ctrl(struct device *device,
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u32_t ctrl_command, void *context);
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/*
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* Currently regarding timers, only loapic timer and arcv2_timer0 implements
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* device pm functionality. For other timers, use default handler in case
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* the app enables CONFIG_DEVICE_POWER_MANAGEMENT.
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*/
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#if !defined(CONFIG_LOAPIC_TIMER) && !defined(CONFIG_ARCV2_TIMER)
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#define sys_clock_device_ctrl device_pm_control_nop
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#endif
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extern s32_t _sys_idle_elapsed_ticks;
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#define _sys_clock_tick_announce() \
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_nano_sys_clock_tick_announce(_sys_idle_elapsed_ticks)
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/**
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* @brief Account for the tick due to the timer interrupt
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*
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* @return N/A
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*/
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static inline void _sys_clock_final_tick_announce(void)
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{
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/*
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* Ticks are both announced and immediately processed at interrupt
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* level. Thus there is only one tick left to announce (and process).
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*/
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_sys_idle_elapsed_ticks = 1;
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_sys_clock_tick_announce();
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}
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#endif /* _ASMLANGUAGE */
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#ifdef __cplusplus
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}
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#endif
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#endif /* _TIMER__H_ */
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