import less(1)

[unleashed/tickless.git] / usr / src / lib / libc / port / rt / sched.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I%     %E% SMI"

#include "lint.h"
#include "thr_uberdata.h"
#include <sched.h>
#include <sys/tspriocntl.h>
#include <sys/rtpriocntl.h>
#include <sys/fxpriocntl.h>

/*
 * The following array is used for caching information
 * for priocntl scheduling classes.
 */
static pcclass_t sched_class[] = {
        {0, SCHED_OTHER, 0, 0, {-1, "TS",  0}},
        {0, SCHED_FIFO,  0, 0, {-1, "RT",  0}},
        {0, SCHED_RR,    0, 0, {-1, "RT",  0}},
        {0, SCHED_SYS,   0, 0, {0,  "SYS", 0}},
        {0, SCHED_IA,    0, 0, {-1, "IA",  0}},
        {0, SCHED_FSS,   0, 0, {-1, "FSS", 0}},
        {0, SCHED_FX,    0, 0, {-1, "FX",  0}},
        /*
         * Allow unknown (to us) scheduling classes.
         * The kernel allows space for exactly 10 scheduling classes
         * (see the definitions of 'sclass' and 'nclass' in the kernel).
         * We need that number of available slots here.
         * If the kernel space is changed, this has to change too.
         */
        {0, -1,          0, 0, {-1, "",    0}},
        {0, -1,          0, 0, {-1, "",    0}},
        {0, -1,          0, 0, {-1, "",    0}},
        {0, -1,          0, 0, {-1, "",    0}},
        {0, -1,          0, 0, {-1, "",    0}},
        {0, -1,          0, 0, {-1, "",    0}},
        {0, -1,          0, 0, {-1, "",    0}},
        {0, -1,          0, 0, {-1, "",    0}},
        {0, -1,          0, 0, {-1, "",    0}},
        {0, -1,          0, 0, {-1, "",    0}},
};

#define NPOLICY (sizeof (sched_class) / sizeof (pcclass_t))

#if _SCHED_NEXT != SCHED_FX + 1
#error "fatal: _SCHED_NEXT != SCHED_FX + 1"
#endif

static mutex_t class_lock = DEFAULTMUTEX;       /* protects sched_class[] */

/*
 * Helper function for get_info_by_policy(), below.
 * Don't let a manufactured policy number duplicate
 * the class of one of our base policy numbers.
 */
static int
is_base_class(const char *clname)
{
        const pcclass_t *pccp;
        int             policy;

        for (policy = 0, pccp = sched_class;
            policy < _SCHED_NEXT;
            policy++, pccp++) {
                if (strcmp(clname, pccp->pcc_info.pc_clname) == 0)
                        return (1);
        }
        return (0);
}

/*
 * Cache priocntl information on scheduling class by policy.
 */
const pcclass_t *
get_info_by_policy(int policy)
{
        pcclass_t *pccp = &sched_class[policy];
        pcpri_t pcpri;
        pri_t prio;
        int base = 0;

        if ((uint_t)policy >= NPOLICY || pccp->pcc_state < 0) {
                errno = EINVAL;
                return (NULL);
        }

        if (pccp->pcc_state > 0)
                return (pccp);

        lmutex_lock(&class_lock);

        /* get class info (the system class is known to have class-id == 0) */
        if (pccp->pcc_policy == -1) {
                /* policy number not defined in <sched.h> */
                ASSERT(policy >= _SCHED_NEXT);
                pccp->pcc_info.pc_cid = policy - _SCHED_NEXT;
                if (priocntl(0, 0, PC_GETCLINFO, &pccp->pcc_info) == -1 ||
                    (base = is_base_class(pccp->pcc_info.pc_clname)) != 0) {
                        pccp->pcc_info.pc_clname[0] = '\0';
                        pccp->pcc_info.pc_cid = -1;
                        /*
                         * If we duplicated a base class, permanently
                         * disable this policy entry.  Else allow for
                         * dynamic loading of scheduling classes.
                         */
                        if (base) {
                                membar_producer();
                                pccp->pcc_state = -1;
                        }
                        errno = EINVAL;
                        lmutex_unlock(&class_lock);
                        return (NULL);
                }
                pccp->pcc_policy = policy;
        } else if (policy != SCHED_SYS &&
            priocntl(0, 0, PC_GETCID, &pccp->pcc_info) == -1) {
                membar_producer();
                pccp->pcc_state = -1;
                errno = EINVAL;
                lmutex_unlock(&class_lock);
                return (NULL);
        }

        switch (policy) {
        case SCHED_OTHER:
                prio = ((tsinfo_t *)pccp->pcc_info.pc_clinfo)->ts_maxupri;
                pccp->pcc_primin = -prio;
                pccp->pcc_primax = prio;
                break;
        case SCHED_FIFO:
        case SCHED_RR:
                prio = ((rtinfo_t *)pccp->pcc_info.pc_clinfo)->rt_maxpri;
                pccp->pcc_primin = 0;
                pccp->pcc_primax = prio;
                break;
        default:
                /*
                 * All other policy numbers, including policy numbers
                 * not defined in <sched.h>.
                 */
                pcpri.pc_cid = pccp->pcc_info.pc_cid;
                if (priocntl(0, 0, PC_GETPRIRANGE, &pcpri) == 0) {
                        pccp->pcc_primin = pcpri.pc_clpmin;
                        pccp->pcc_primax = pcpri.pc_clpmax;
                }
                break;
        }

        membar_producer();
        pccp->pcc_state = 1;
        lmutex_unlock(&class_lock);
        return (pccp);
}

const pcclass_t *
get_info_by_class(id_t classid)
{
        pcinfo_t        pcinfo;
        pcclass_t       *pccp;
        int             policy;

        if (classid < 0) {
                errno = EINVAL;
                return (NULL);
        }

        /* determine if we already know this classid */
        for (policy = 0, pccp = sched_class;
            policy < NPOLICY;
            policy++, pccp++) {
                if (pccp->pcc_state > 0 && pccp->pcc_info.pc_cid == classid)
                        return (pccp);
        }

        pcinfo.pc_cid = classid;
        if (priocntl(0, 0, PC_GETCLINFO, &pcinfo) == -1) {
                if (classid == 0)       /* no kernel info for sys class */
                        return (get_info_by_policy(SCHED_SYS));
                return (NULL);
        }

        for (policy = 0, pccp = sched_class;
            policy < NPOLICY;
            policy++, pccp++) {
                if (pccp->pcc_state == 0 &&
                    strcmp(pcinfo.pc_clname, pccp->pcc_info.pc_clname) == 0)
                        return (get_info_by_policy(pccp->pcc_policy));
        }

        /*
         * We have encountered an unknown (to us) scheduling class.
         * Manufacture a policy number for it.  Hopefully we still
         * have room in the sched_class[] table.
         */
        policy = _SCHED_NEXT + classid;
        if (policy >= NPOLICY) {
                errno = EINVAL;
                return (NULL);
        }
        lmutex_lock(&class_lock);
        pccp = &sched_class[policy];
        pccp->pcc_policy = policy;
        (void) strlcpy(pccp->pcc_info.pc_clname, pcinfo.pc_clname, PC_CLNMSZ);
        lmutex_unlock(&class_lock);
        return (get_info_by_policy(pccp->pcc_policy));
}

/*
 * Helper function: get process or lwp current scheduling policy.
 */
static const pcclass_t *
get_parms(idtype_t idtype, id_t id, pcparms_t *pcparmp)
{
        pcparmp->pc_cid = PC_CLNULL;
        if (priocntl(idtype, id, PC_GETPARMS, pcparmp) == -1)
                return (NULL);
        return (get_info_by_class(pcparmp->pc_cid));
}

/*
 * Helper function for setprio() and setparam(), below.
 */
static int
set_priority(idtype_t idtype, id_t id, int policy, int prio,
    pcparms_t *pcparmp, int settq)
{
        int rv;

        switch (policy) {
        case SCHED_OTHER:
        {
                tsparms_t *tsp = (tsparms_t *)pcparmp->pc_clparms;
                tsp->ts_uprilim = prio;
                tsp->ts_upri = prio;
                break;
        }
        case SCHED_FIFO:
        case SCHED_RR:
        {
                rtparms_t *rtp = (rtparms_t *)pcparmp->pc_clparms;
                rtp->rt_tqnsecs = settq?
                    (policy == SCHED_FIFO? RT_TQINF : RT_TQDEF) :
                    RT_NOCHANGE;
                rtp->rt_pri = prio;
                break;
        }
        default:
        {
                /*
                 * Class-independent method for setting the priority.
                 */
                pcprio_t pcprio;

                pcprio.pc_op = PC_SETPRIO;
                pcprio.pc_cid = pcparmp->pc_cid;
                pcprio.pc_val = prio;
                do {
                        rv = priocntl(idtype, id, PC_DOPRIO, &pcprio);
                } while (rv == -1 && errno == ENOMEM);
                return (rv);
        }
        }

        do {
                rv = priocntl(idtype, id, PC_SETPARMS, pcparmp);
        } while (rv == -1 && errno == ENOMEM);
        return (rv);
}

/*
 * Utility function, private to libc, used by sched_setparam()
 * and posix_spawn().  Because it is called by the vfork() child of
 * posix_spawn(), we must not call any functions exported from libc.
 */
id_t
setprio(idtype_t idtype, id_t id, int prio, int *policyp)
{
        pcparms_t       pcparm;
        int             policy;
        const pcclass_t *pccp;

        if ((pccp = get_parms(idtype, id, &pcparm)) == NULL)
                return (-1);
        if (prio < pccp->pcc_primin || prio > pccp->pcc_primax) {
                errno = EINVAL;
                return (-1);
        }

        policy = pccp->pcc_policy;
        if (policyp != NULL &&
            (policy == SCHED_FIFO || policy == SCHED_RR)) {
                rtparms_t *rtp = (rtparms_t *)pcparm.pc_clparms;
                policy = (rtp->rt_tqnsecs == RT_TQINF? SCHED_FIFO : SCHED_RR);
        }

        if (set_priority(idtype, id, policy, prio, &pcparm, 0) == -1)
                return (-1);
        if (policyp != NULL)
                *policyp = policy;
        return (pccp->pcc_info.pc_cid);
}

int
sched_setparam(pid_t pid, const struct sched_param *param)
{
        if (pid < 0) {
                errno = ESRCH;
                return (-1);
        }
        if (pid == 0)
                pid = P_MYID;

        if (setprio(P_PID, pid, param->sched_priority, NULL) == -1)
                return (-1);
        return (0);
}

id_t
getparam(idtype_t idtype, id_t id, int *policyp, struct sched_param *param)
{
        pcparms_t pcparm;
        const pcclass_t *pccp;
        int policy;
        int priority;

        if ((pccp = get_parms(idtype, id, &pcparm)) == NULL)
                return (-1);

        switch (policy = pccp->pcc_policy) {
        case SCHED_OTHER:
        {
                tsparms_t *tsp = (tsparms_t *)pcparm.pc_clparms;
                priority = tsp->ts_upri;
                break;
        }
        case SCHED_FIFO:
        case SCHED_RR:
        {
                rtparms_t *rtp = (rtparms_t *)pcparm.pc_clparms;
                priority = rtp->rt_pri;
                policy = (rtp->rt_tqnsecs == RT_TQINF? SCHED_FIFO : SCHED_RR);
                break;
        }
        default:
        {
                /*
                 * Class-independent method for getting the priority.
                 */
                pcprio_t pcprio;

                pcprio.pc_op = PC_GETPRIO;
                pcprio.pc_cid = 0;
                pcprio.pc_val = 0;
                if (priocntl(idtype, id, PC_DOPRIO, &pcprio) == 0)
                        priority = pcprio.pc_val;
                else
                        priority = 0;
                break;
        }
        }

        *policyp = policy;
        (void) memset(param, 0, sizeof (*param));
        param->sched_priority = priority;

        return (pcparm.pc_cid);
}

int
sched_getparam(pid_t pid, struct sched_param *param)
{
        int policy;

        if (pid < 0) {
                errno = ESRCH;
                return (-1);
        }
        if (pid == 0)
                pid = P_MYID;

        if (getparam(P_PID, pid, &policy, param) == -1)
                return (-1);
        return (0);
}

/*
 * Utility function, private to libc, used by sched_setscheduler()
 * and posix_spawn().  Because it is called by the vfork() child of
 * posix_spawn(), we must not call any functions exported from libc.
 */
id_t
setparam(idtype_t idtype, id_t id, int policy, int prio)
{
        pcparms_t       pcparm;
        const pcclass_t *pccp;

        if (policy == SCHED_SYS ||
            (pccp = get_info_by_policy(policy)) == NULL ||
            prio < pccp->pcc_primin || prio > pccp->pcc_primax) {
                errno = EINVAL;
                return (-1);
        }

        pcparm.pc_cid = pccp->pcc_info.pc_cid;
        if (set_priority(idtype, id, policy, prio, &pcparm, 1) == -1)
                return (-1);
        return (pccp->pcc_info.pc_cid);
}

int
sched_setscheduler(pid_t pid, int policy, const struct sched_param *param)
{
        pri_t           prio = param->sched_priority;
        int             oldpolicy;

        if ((oldpolicy = sched_getscheduler(pid)) < 0)
                return (-1);

        if (pid == 0)
                pid = P_MYID;

        if (setparam(P_PID, pid, policy, prio) == -1)
                return (-1);

        return (oldpolicy);
}

int
sched_getscheduler(pid_t pid)
{
        pcparms_t       pcparm;
        const pcclass_t *pccp;
        int             policy;

        if (pid < 0) {
                errno = ESRCH;
                return (-1);
        }
        if (pid == 0)
                pid = P_MYID;

        if ((pccp = get_parms(P_PID, pid, &pcparm)) == NULL)
                return (-1);

        if ((policy = pccp->pcc_policy) == SCHED_FIFO || policy == SCHED_RR) {
                policy =
                    (((rtparms_t *)pcparm.pc_clparms)->rt_tqnsecs == RT_TQINF?
                    SCHED_FIFO : SCHED_RR);
        }

        return (policy);
}

int
sched_yield(void)
{
        yield();
        return (0);
}

int
sched_get_priority_max(int policy)
{
        const pcclass_t *pccp;

        if ((pccp = get_info_by_policy(policy)) != NULL)
                return (pccp->pcc_primax);
        errno = EINVAL;
        return (-1);
}

int
sched_get_priority_min(int policy)
{
        const pcclass_t *pccp;

        if ((pccp = get_info_by_policy(policy)) != NULL)
                return (pccp->pcc_primin);
        errno = EINVAL;
        return (-1);
}

int
sched_rr_get_interval(pid_t pid, timespec_t *interval)
{
        pcparms_t pcparm;
        const pcclass_t *pccp;

        if (pid < 0) {
                errno = ESRCH;
                return (-1);
        }
        if (pid == 0)
                pid = P_MYID;

        if ((pccp = get_parms(P_PID, pid, &pcparm)) == NULL)
                return (-1);

        /*
         * At the moment, we have no class-independent method to fetch
         * the process/lwp time quantum.  Since SUSv3 does not restrict
         * this operation to the real-time class, we return an indefinite
         * quantum (tv_sec == 0 and tv_nsec == 0) for scheduling policies
         * for which this information isn't available.
         */
        interval->tv_sec = 0;
        interval->tv_nsec = 0;

        switch (pccp->pcc_policy) {
        case SCHED_FIFO:
        case SCHED_RR:
                {
                        rtparms_t *rtp = (rtparms_t *)pcparm.pc_clparms;
                        if (rtp->rt_tqnsecs != RT_TQINF) {
                                interval->tv_sec = rtp->rt_tqsecs;
                                interval->tv_nsec = rtp->rt_tqnsecs;
                        }
                }
                break;
        case SCHED_FX:
                {
                        fxparms_t *fxp = (fxparms_t *)pcparm.pc_clparms;
                        if (fxp->fx_tqnsecs != FX_TQINF) {
                                interval->tv_sec = fxp->fx_tqsecs;
                                interval->tv_nsec = fxp->fx_tqnsecs;
                        }
                }
                break;
        }

        return (0);
}

/*
 * Initialize or update ul_policy, ul_cid, and ul_pri.
 */
void
update_sched(ulwp_t *self)
{
        volatile sc_shared_t *scp;
        pcparms_t pcparm;
        pcprio_t pcprio;
        const pcclass_t *pccp;
        int priority;
        int policy;

        ASSERT(self == curthread);

        enter_critical(self);

        if ((scp = self->ul_schedctl) == NULL &&
            (scp = setup_schedctl()) == NULL) {         /* can't happen? */
                if (self->ul_policy < 0) {
                        self->ul_cid = 0;
                        self->ul_pri = 0;
                        membar_producer();
                        self->ul_policy = SCHED_OTHER;
                }
                exit_critical(self);
                return;
        }

        if (self->ul_policy >= 0 &&
            self->ul_cid == scp->sc_cid &&
            (self->ul_pri == scp->sc_cpri ||
            (self->ul_epri > 0 && self->ul_epri == scp->sc_cpri))) {
                exit_critical(self);
                return;
        }

        pccp = get_parms(P_LWPID, P_MYID, &pcparm);
        if (pccp == NULL) {             /* can't happen? */
                self->ul_cid = scp->sc_cid;
                self->ul_pri = scp->sc_cpri;
                membar_producer();
                self->ul_policy = SCHED_OTHER;
                exit_critical(self);
                return;
        }

        switch (policy = pccp->pcc_policy) {
        case SCHED_OTHER:
                priority = ((tsparms_t *)pcparm.pc_clparms)->ts_upri;
                break;
        case SCHED_FIFO:
        case SCHED_RR:
                self->ul_rtclassid = pccp->pcc_info.pc_cid;
                priority = ((rtparms_t *)pcparm.pc_clparms)->rt_pri;
                policy =
                    ((rtparms_t *)pcparm.pc_clparms)->rt_tqnsecs == RT_TQINF?
                    SCHED_FIFO : SCHED_RR;
                break;
        default:
                /*
                 * Class-independent method for getting the priority.
                 */
                pcprio.pc_op = PC_GETPRIO;
                pcprio.pc_cid = 0;
                pcprio.pc_val = 0;
                if (priocntl(P_LWPID, P_MYID, PC_DOPRIO, &pcprio) == 0)
                        priority = pcprio.pc_val;
                else
                        priority = 0;
        }

        self->ul_cid = pcparm.pc_cid;
        self->ul_pri = priority;
        membar_producer();
        self->ul_policy = policy;

        exit_critical(self);
}