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)
40 lines
1.2 KiB
C
40 lines
1.2 KiB
C
#include "kernel/system.h"
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#include <signal.h>
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#include <sys/sigcontext.h>
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#include <minix/endpoint.h>
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#include "kernel/clock.h"
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/*===========================================================================*
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* do_schedule *
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*===========================================================================*/
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PUBLIC int do_schedule(struct proc * caller, message * m_ptr)
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{
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struct proc *p;
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p = proc_addr(_ENDPOINT_P(m_ptr->SCHEDULING_ENDPOINT));
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/* Only this process' scheduler can schedule it */
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if (caller != p->p_scheduler)
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return(EPERM);
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/* Make sure the priority number given is within the allowed range.*/
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if (m_ptr->SCHEDULING_PRIORITY < TASK_Q ||
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m_ptr->SCHEDULING_PRIORITY > NR_SCHED_QUEUES)
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return(EINVAL);
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/* In some cases, we might be rescheduling a runnable process. In such
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* a case (i.e. if we are updating the priority) we set the NO_QUANTUM
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* flag before the generic unset to dequeue/enqueue the process
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*/
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if (proc_is_runnable(p))
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RTS_SET(p, RTS_NO_QUANTUM);
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/* Clear the scheduling bit and enqueue the process */
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p->p_priority = m_ptr->SCHEDULING_PRIORITY;
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p->p_quantum_size_ms = m_ptr->SCHEDULING_QUANTUM;
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p->p_cpu_time_left = ms_2_cpu_time(m_ptr->SCHEDULING_QUANTUM);
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RTS_UNSET(p, RTS_NO_QUANTUM);
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return(OK);
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}
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