mirror of
https://github.com/zephyrproject-rtos/zephyr
synced 2025-08-10 11:46:07 +00:00
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>
130 lines
3.3 KiB
C
130 lines
3.3 KiB
C
/*
|
|
* Copyright (c) 2014-2015 Wind River Systems, Inc.
|
|
*
|
|
* SPDX-License-Identifier: Apache-2.0
|
|
*/
|
|
|
|
/**
|
|
* @file
|
|
* @brief Variables needed needed for system clock
|
|
*
|
|
*
|
|
* Declare variables used by both system timer device driver and kernel
|
|
* components that use timer functionality.
|
|
*/
|
|
|
|
#ifndef _SYS_CLOCK__H_
|
|
#define _SYS_CLOCK__H_
|
|
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif
|
|
|
|
#ifndef _ASMLANGUAGE
|
|
#include <zephyr/types.h>
|
|
|
|
#if defined(CONFIG_SYS_CLOCK_EXISTS) && \
|
|
(CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC == 0)
|
|
#error "SYS_CLOCK_HW_CYCLES_PER_SEC must be non-zero!"
|
|
#endif
|
|
|
|
#ifdef CONFIG_TICKLESS_KERNEL
|
|
#define sys_clock_ticks_per_sec \
|
|
(1000000 / (CONFIG_TICKLESS_KERNEL_TIME_UNIT_IN_MICRO_SECS))
|
|
extern int _sys_clock_always_on;
|
|
extern void _enable_sys_clock(void);
|
|
#else
|
|
#define sys_clock_ticks_per_sec CONFIG_SYS_CLOCK_TICKS_PER_SEC
|
|
#endif
|
|
|
|
#if defined(CONFIG_TIMER_READS_ITS_FREQUENCY_AT_RUNTIME)
|
|
extern int sys_clock_hw_cycles_per_sec;
|
|
#else
|
|
#define sys_clock_hw_cycles_per_sec CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC
|
|
#endif
|
|
|
|
/*
|
|
* sys_clock_us_per_tick global variable represents a number
|
|
* of microseconds in one OS timer tick
|
|
*/
|
|
extern int sys_clock_us_per_tick;
|
|
|
|
/*
|
|
* sys_clock_hw_cycles_per_tick global variable represents a number
|
|
* of platform clock ticks in one OS timer tick.
|
|
* sys_clock_hw_cycles_per_tick often represents a value of divider
|
|
* of the board clock frequency
|
|
*/
|
|
extern int sys_clock_hw_cycles_per_tick;
|
|
|
|
/* number of nsec per usec */
|
|
#define NSEC_PER_USEC 1000
|
|
|
|
/* number of microseconds per millisecond */
|
|
#define USEC_PER_MSEC 1000
|
|
|
|
/* number of milliseconds per second */
|
|
#define MSEC_PER_SEC 1000
|
|
|
|
/* number of microseconds per second */
|
|
#define USEC_PER_SEC ((USEC_PER_MSEC) * (MSEC_PER_SEC))
|
|
|
|
/* number of nanoseconds per second */
|
|
#define NSEC_PER_SEC ((NSEC_PER_USEC) * (USEC_PER_MSEC) * (MSEC_PER_SEC))
|
|
|
|
|
|
/* SYS_CLOCK_HW_CYCLES_TO_NS64 converts CPU clock cycles to nanoseconds */
|
|
#define SYS_CLOCK_HW_CYCLES_TO_NS64(X) \
|
|
(((u64_t)(X) * sys_clock_us_per_tick * NSEC_PER_USEC) / \
|
|
sys_clock_hw_cycles_per_tick)
|
|
|
|
/*
|
|
* SYS_CLOCK_HW_CYCLES_TO_NS_AVG converts CPU clock cycles to nanoseconds
|
|
* and calculates the average cycle time
|
|
*/
|
|
#define SYS_CLOCK_HW_CYCLES_TO_NS_AVG(X, NCYCLES) \
|
|
(u32_t)(SYS_CLOCK_HW_CYCLES_TO_NS64(X) / NCYCLES)
|
|
|
|
/**
|
|
* @defgroup clock_apis Kernel Clock APIs
|
|
* @ingroup kernel_apis
|
|
* @{
|
|
*/
|
|
|
|
/**
|
|
* @brief Compute nanoseconds from hardware clock cycles.
|
|
*
|
|
* This macro converts a time duration expressed in hardware clock cycles
|
|
* to the equivalent duration expressed in nanoseconds.
|
|
*
|
|
* @param X Duration in hardware clock cycles.
|
|
*
|
|
* @return Duration in nanoseconds.
|
|
*/
|
|
#define SYS_CLOCK_HW_CYCLES_TO_NS(X) (u32_t)(SYS_CLOCK_HW_CYCLES_TO_NS64(X))
|
|
|
|
/**
|
|
* @} end defgroup clock_apis
|
|
*/
|
|
|
|
extern volatile u64_t _sys_clock_tick_count;
|
|
|
|
/*
|
|
* Number of ticks for x seconds. NOTE: With MSEC() or USEC(),
|
|
* since it does an integer division, x must be greater or equal to
|
|
* 1000/sys_clock_ticks_per_sec to get a non-zero value.
|
|
* You may want to raise CONFIG_SYS_CLOCK_TICKS_PER_SEC depending on
|
|
* your requirements.
|
|
*/
|
|
#define SECONDS(x) ((x) * sys_clock_ticks_per_sec)
|
|
#define MSEC(x) (SECONDS(x) / MSEC_PER_SEC)
|
|
#define USEC(x) (MSEC(x) / USEC_PER_MSEC)
|
|
|
|
#endif /* !_ASMLANGUAGE */
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
|
|
#endif /* _SYS_CLOCK__H_ */
|