| 1 | /* The kernel call implemented in this file:
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| 2 | * m_type: SYS_NICE
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| 3 | *
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| 4 | * The parameters for this kernel call are:
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| 5 | * m1_i1: PR_PROC_NR process number to change priority
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| 6 | * m1_i2: PR_PRIORITY the new priority
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| 7 | */
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| 8 |
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| 9 | #include "../system.h"
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| 10 | #include <minix/type.h>
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| 11 | #include <sys/resource.h>
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| 12 |
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| 13 | #if USE_NICE
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| 14 |
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| 15 | /*===========================================================================*
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| 16 | * do_nice *
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| 17 | *===========================================================================*/
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| 18 | PUBLIC int do_nice(message *m_ptr)
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| 19 | {
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| 20 | int proc_nr, pri, new_q ;
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| 21 | register struct proc *rp;
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| 22 |
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| 23 | /* Extract the message parameters and do sanity checking. */
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| 24 | proc_nr = m_ptr->PR_PROC_NR;
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| 25 | if (! isokprocn(proc_nr)) return(EINVAL);
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| 26 | if (iskerneln(proc_nr)) return(EPERM);
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| 27 | pri = m_ptr->PR_PRIORITY;
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| 28 | if (pri < PRIO_MIN || pri > PRIO_MAX) return(EINVAL);
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| 29 |
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| 30 | /* The priority is currently between PRIO_MIN and PRIO_MAX. We have to
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| 31 | * scale this between MIN_USER_Q and MAX_USER_Q.
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| 32 | */
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| 33 | new_q = MAX_USER_Q + (pri-PRIO_MIN) * (MIN_USER_Q-MAX_USER_Q+1) /
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| 34 | (PRIO_MAX-PRIO_MIN+1);
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| 35 | if (new_q < MAX_USER_Q) new_q = MAX_USER_Q; /* shouldn't happen */
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| 36 | if (new_q > MIN_USER_Q) new_q = MIN_USER_Q; /* shouldn't happen */
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| 37 |
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| 38 | /* Make sure the process is not running while changing its priority; the
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| 39 | * max_priority is the base priority. Put the process back in its new
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| 40 | * queue if it is runnable.
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| 41 | */
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| 42 | rp = proc_addr(proc_nr);
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| 43 | lock_dequeue(rp);
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| 44 | rp->p_max_priority = rp->p_priority = new_q;
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| 45 | if (! rp->p_rts_flags) lock_enqueue(rp);
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| 46 |
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| 47 | return(OK);
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| 48 | }
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| 49 |
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| 50 | #endif /* USE_NICE */
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| 51 |
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