Kernel internals providing services of delayed and periodic execution. More...

Data Structures
struct	TimerEntry_t
	Description of one sleep request. More...

Macros
#define	TIMER_INVALID_ID 0xFF

Enumerations
enum	eSleepType { TIMER_SLEEP = 0 , TIMER_TIMEOUT , TIMER_PERIODIC , TIMER_INTERVAL = TIMER_PERIODIC }

Functions
static bool	is_periodic (struct TimerEntry_t *entry)
	Determine if interval in sleep entry is periodic or not.

static unsigned	get_sleeptime (const unsigned interval)
	Get how long the sleep should take.

static int	do_set_timed_event (Txn_t txn, unsigned slot, unsigned interval, enum eSleepType type)
	Perform heavy lifting of setting timers This routine will store timed event into list of timed events.

int	os_set_timed_event (unsigned microseconds, enum eSleepType type)
	Find a slot for timed event and store it.

int	os_find_timer (Thread_t owner, enum eSleepType type)
	Find a timer slot matchin owner thread and timer type.

int	os_cancel_timed_event (Thread_t owner, enum eSleepType type)
	Cancels existing timed event.

int	os_cancel_sleeper (int sleeper)
	Cancel existing sleeper.

static void	delay_us (uint32_t period_us)
	Perform short busy wait.

int	os_usleep (unsigned microseconds)
	Kernel implementation of usleep() syscall.

int	os_setitimer (unsigned microseconds)
	Kernel implementation of setitimer() syscall.

void	os_timer_init ()
	This routine initializes kernel scheduling subsystem.

static uint32_t	get_sleep_time (uint32_t sleep_from, uint32_t microtime)
	Helper function to calculate time considering type wraparound.

bool	os_schedule_timer (unsigned *delay)
	Provide information on next scheduled event.

void	os_run_timer (uint32_t microtime)
	Fire scheduled event.

uint32_t	os_cpu_freq_get (void)
	Get current CPU frequency.

Variables
struct TimerEntry_t	sleepers [SLEEPERS_MAX]
	List of all delays requested from kernel.

Detailed Description

Kernel internals providing services of delayed and periodic execution.

Macro Definition Documentation

◆ TIMER_INVALID_ID

#define TIMER_INVALID_ID 0xFF

Enumeration Type Documentation

◆ eSleepType

enum eSleepType

Enumerator
TIMER_SLEEP
TIMER_TIMEOUT
TIMER_PERIODIC
TIMER_INTERVAL

Function Documentation

◆ delay_us()

static void delay_us ( uint32_t period_us )

static

Perform short busy wait.

This will perform busywait in the context of current thread. Useful to do short waits for I/O.

Parameters

period_us how long the wait should take

◆ do_set_timed_event()

static int do_set_timed_event	(	Txn_t	txn,
		unsigned	slot,
		unsigned	interval,
		enum eSleepType	type
	)

static

Perform heavy lifting of setting timers This routine will store timed event into list of timed events.

If event is not periodic, it will also stop thread (os_usleep semantics).

Parameters

txn	transaction used to modify the table
slot	number of slot in sleepers list
interval	amount of us for which thread should sleep
type	type of timer to set up

Returns: 0 if timer was set up properly

◆ get_sleep_time()

static uint32_t get_sleep_time	(	uint32_t	sleep_from,
		uint32_t	microtime
	)

static

Helper function to calculate time considering type wraparound.

This function will calculate the final time considering timer wraparound.

Parameters

sleep_from	time at which the sleep starts (microseconds)
microtime	duration of sleep (microseconds)

Returns: new value of kernel timer at the end of sleep

◆ get_sleeptime()

static unsigned get_sleeptime ( const unsigned interval )

static

Get how long the sleep should take.

Will clean the periodicity flag from interval.

Returns: sleep time in microseconds.

◆ is_periodic()

static bool is_periodic ( struct TimerEntry_t * entry )

static

Determine if interval in sleep entry is periodic or not.

Returns: 1 if interval is periodic, 0 if interval is one-shot.

◆ os_cancel_sleeper()

int os_cancel_sleeper ( int sleeper )

Cancel existing sleeper.

This function will cancel existing sleeper. It is useful for cases where you already know the identity of the sleeper in advance.

Parameters

sleeper ID of the sleeper being cancelled

Returns: 0 is operation performed successfully

◆ os_cancel_timed_event()

int os_cancel_timed_event	(	Thread_t	owner,
		enum eSleepType	type
	)

Cancels existing timed event.

This function is only accessible for periodic timers externally. It allows cancelling of interval timers set previously.

Parameters

owner	thread which shall own the interval timer
type	type of the event to be cancelled

Returns: 0 if operation performed successfully.

◆ os_cpu_freq_get()

uint32_t os_cpu_freq_get ( void )

Get current CPU frequency.

Will return the current CPU frequency (if known and/or available).

Returns: CPU frequency in Hz, 0 if value is not known.

◆ os_find_timer()

int os_find_timer	(	Thread_t	owner,
		enum eSleepType	type
	)

Find a timer slot matchin owner thread and timer type.

This will find a slot which bears the timer of given type for given thread.

Parameters

[in]	owner	thread ID which should own the timer
[in]	type	type of the timer.

◆ os_run_timer()

void os_run_timer ( uint32_t microtime )

Fire scheduled event.

Will find and run scheduled event.

Parameters

microtime current processor time in microseconds

◆ os_schedule_timer()

bool os_schedule_timer ( unsigned * delay )

Provide information on next scheduled event.

This function informs caller about delay until next scheduled event. Next scheduled event may be either wake-up of sleeped thread, or interval timer.

Parameters

[out] delay address of buffer, where delay to next scheduled event will be written

Returns: true if there is any scheduled event known and at address pointed to by delay value was written. Returns false if there is no known scheduled event. In such case content of memory pointed to by delay is undefined.

◆ os_set_timed_event()

int os_set_timed_event	(	unsigned	microseconds,
		enum eSleepType	type
	)

Find a slot for timed event and store it.

This is actual execution core for both os_usleep and os_setitimer functions. It will find free slot or slot already occupied by calling thread and will set / update timeout values.

Parameters

microseconds	time for which thread should sleep / wait for event
type	type of timed event to set up

Returns: error status. 0 means no error.

◆ os_setitimer()

int os_setitimer ( unsigned microseconds )

Kernel implementation of setitimer() syscall.

See setitimer for details on arguments.

◆ os_timer_init()

void os_timer_init ( )

This routine initializes kernel scheduling subsystem.

It is necessary to call this routine before first call to either timer syscalls, or os_run_timer otherwise things will go wrong.

◆ os_usleep()

int os_usleep ( unsigned microseconds )

Kernel implementation of usleep() syscall.

See usleep for details on arguments.

Variable Documentation

◆ sleepers

struct TimerEntry_t sleepers[SLEEPERS_MAX]

List of all delays requested from kernel.

This structure contains all scheduled sleeps requested by all threads. Every thread can technically request one periodic timer and one one-shot delay.

Data Structures

Macros

Enumerations

Functions

Variables

Detailed Description

Macro Definition Documentation

◆ TIMER_INVALID_ID

Enumeration Type Documentation

◆ eSleepType

Function Documentation

◆ delay_us()

◆ do_set_timed_event()

◆ get_sleep_time()

◆ get_sleeptime()

◆ is_periodic()

◆ os_cancel_sleeper()

◆ os_cancel_timed_event()

◆ os_cpu_freq_get()

◆ os_find_timer()

◆ os_run_timer()

◆ os_schedule_timer()

◆ os_set_timed_event()

◆ os_setitimer()

◆ os_timer_init()

◆ os_usleep()

Variable Documentation

◆ sleepers