451a6890d6
- Currently the cpu time quantum is timer-ticks based. Thus the remaining quantum is decreased only if the processes is interrupted by a timer tick. As processes block a lot this typically does not happen for normal user processes. Also the quantum depends on the frequency of the timer. - This change makes the quantum miliseconds based. Internally the miliseconds are translated into cpu cycles. Everytime userspace execution is interrupted by kernel the cycles just consumed by the current process are deducted from the remaining quantum. - It makes the quantum system timer frequency independent. - The boot processes quantum is loosely derived from the tick-based quantas and 60Hz timer and subject to future change - the 64bit arithmetics is a little ugly, will be changes once we have compiler support for 64bit integers (soon)
74 lines
2.6 KiB
C
74 lines
2.6 KiB
C
/* The kernel call implemented in this file:
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* m_type: SYS_SETALARM
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*
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* The parameters for this kernel call are:
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* m2_l1: ALRM_EXP_TIME (alarm's expiration time)
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* m2_i2: ALRM_ABS_TIME (expiration time is absolute?)
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* m2_l1: ALRM_TIME_LEFT (return seconds left of previous)
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*/
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#include "kernel/system.h"
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#include <minix/endpoint.h>
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#include <assert.h>
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#if USE_SETALARM
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FORWARD _PROTOTYPE( void cause_alarm, (timer_t *tp) );
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/*===========================================================================*
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* do_setalarm *
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*===========================================================================*/
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PUBLIC int do_setalarm(struct proc * caller, message * m_ptr)
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{
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/* A process requests a synchronous alarm, or wants to cancel its alarm. */
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long exp_time; /* expiration time for this alarm */
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int use_abs_time; /* use absolute or relative time */
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timer_t *tp; /* the process' timer structure */
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clock_t uptime; /* placeholder for current uptime */
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/* Extract shared parameters from the request message. */
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exp_time = m_ptr->ALRM_EXP_TIME; /* alarm's expiration time */
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use_abs_time = m_ptr->ALRM_ABS_TIME; /* flag for absolute time */
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if (! (priv(caller)->s_flags & SYS_PROC)) return(EPERM);
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/* Get the timer structure and set the parameters for this alarm. */
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tp = &(priv(caller)->s_alarm_timer);
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tmr_arg(tp)->ta_int = m_ptr->m_source;
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tp->tmr_func = cause_alarm;
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/* Return the ticks left on the previous alarm. */
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uptime = get_uptime();
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if ((tp->tmr_exp_time != TMR_NEVER) && (uptime < tp->tmr_exp_time) ) {
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m_ptr->ALRM_TIME_LEFT = (tp->tmr_exp_time - uptime);
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} else {
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m_ptr->ALRM_TIME_LEFT = 0;
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}
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/* Finally, (re)set the timer depending on the expiration time. */
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if (exp_time == 0) {
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reset_timer(tp);
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} else {
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tp->tmr_exp_time = (use_abs_time) ? exp_time : exp_time + get_uptime();
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assert(tp->tmr_exp_time > get_uptime());
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set_timer(tp, tp->tmr_exp_time, tp->tmr_func);
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}
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return(OK);
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}
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/*===========================================================================*
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* cause_alarm *
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*===========================================================================*/
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PRIVATE void cause_alarm(tp)
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timer_t *tp;
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{
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/* Routine called if a timer goes off and the process requested a synchronous
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* alarm. The process number is stored in timer argument 'ta_int'. Notify that
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* process with a notification message from CLOCK.
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*/
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int proc_nr_e = tmr_arg(tp)->ta_int; /* get process number */
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mini_notify(proc_addr(CLOCK), proc_nr_e); /* notify process */
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}
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#endif /* USE_SETALARM */
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