kernel - kernel - Incidental MPLOCK removal (usched, affinity)

[dragonfly.git] / sys / kern / usched_bsd4.c

/*
 * Copyright (c) 2012 The DragonFly Project.  All rights reserved.
 * Copyright (c) 1999 Peter Wemm <peter@FreeBSD.org>.  All rights reserved.
 *
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@backplane.com>,
 * by Mihai Carabas <mihai.carabas@gmail.com>
 * and many others.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/queue.h>
#include <sys/proc.h>
#include <sys/rtprio.h>
#include <sys/uio.h>
#include <sys/sysctl.h>
#include <sys/resourcevar.h>
#include <sys/spinlock.h>
#include <sys/cpu_topology.h>
#include <sys/thread2.h>
#include <sys/spinlock2.h>

#include <sys/ktr.h>

#include <machine/cpu.h>
#include <machine/smp.h>

/*
 * Priorities.  Note that with 32 run queues per scheduler each queue
 * represents four priority levels.
 */

#define MAXPRI                  128
#define PRIMASK                 (MAXPRI - 1)
#define PRIBASE_REALTIME        0
#define PRIBASE_NORMAL          MAXPRI
#define PRIBASE_IDLE            (MAXPRI * 2)
#define PRIBASE_THREAD          (MAXPRI * 3)
#define PRIBASE_NULL            (MAXPRI * 4)

#define NQS     32                      /* 32 run queues. */
#define PPQ     (MAXPRI / NQS)          /* priorities per queue */
#define PPQMASK (PPQ - 1)

/*
 * NICEPPQ      - number of nice units per priority queue
 *
 * ESTCPUPPQ    - number of estcpu units per priority queue
 * ESTCPUMAX    - number of estcpu units
 */
#define NICEPPQ         2
#define ESTCPUPPQ       512
#define ESTCPUMAX       (ESTCPUPPQ * NQS)
#define BATCHMAX        (ESTCPUFREQ * 30)
#define PRIO_RANGE      (PRIO_MAX - PRIO_MIN + 1)

#define ESTCPULIM(v)    min((v), ESTCPUMAX)

TAILQ_HEAD(rq, lwp);

#define lwp_priority    lwp_usdata.bsd4.priority
#define lwp_rqindex     lwp_usdata.bsd4.rqindex
#define lwp_estcpu      lwp_usdata.bsd4.estcpu
#define lwp_batch       lwp_usdata.bsd4.batch
#define lwp_rqtype      lwp_usdata.bsd4.rqtype

static void bsd4_acquire_curproc(struct lwp *lp);
static void bsd4_release_curproc(struct lwp *lp);
static void bsd4_select_curproc(globaldata_t gd);
static void bsd4_setrunqueue(struct lwp *lp);
static void bsd4_schedulerclock(struct lwp *lp, sysclock_t period,
                                sysclock_t cpstamp);
static void bsd4_recalculate_estcpu(struct lwp *lp);
static void bsd4_resetpriority(struct lwp *lp);
static void bsd4_forking(struct lwp *plp, struct lwp *lp);
static void bsd4_exiting(struct lwp *lp, struct proc *);
static void bsd4_uload_update(struct lwp *lp);
static void bsd4_yield(struct lwp *lp);
static void bsd4_need_user_resched_remote(void *dummy);
static int bsd4_batchy_looser_pri_test(struct lwp* lp);
static struct lwp *bsd4_chooseproc_locked_cache_coherent(struct lwp *chklp);
static void bsd4_kick_helper(struct lwp *lp);
static struct lwp *bsd4_chooseproc_locked(struct lwp *chklp);
static void bsd4_remrunqueue_locked(struct lwp *lp);
static void bsd4_setrunqueue_locked(struct lwp *lp);
static void bsd4_changedcpu(struct lwp *lp);

struct usched usched_bsd4 = {
        { NULL },
        "bsd4", "Original DragonFly Scheduler",
        NULL,                   /* default registration */
        NULL,                   /* default deregistration */
        bsd4_acquire_curproc,
        bsd4_release_curproc,
        bsd4_setrunqueue,
        bsd4_schedulerclock,
        bsd4_recalculate_estcpu,
        bsd4_resetpriority,
        bsd4_forking,
        bsd4_exiting,
        bsd4_uload_update,
        NULL,                   /* setcpumask not supported */
        bsd4_yield,
        bsd4_changedcpu
};

struct usched_bsd4_pcpu {
        struct thread   *helper_thread;
        short           rrcount;
        short           upri;
        struct lwp      *uschedcp;
        struct lwp      *old_uschedcp;
        cpu_node_t      *cpunode;
};

typedef struct usched_bsd4_pcpu *bsd4_pcpu_t;

/*
 * We have NQS (32) run queues per scheduling class.  For the normal
 * class, there are 128 priorities scaled onto these 32 queues.  New
 * processes are added to the last entry in each queue, and processes
 * are selected for running by taking them from the head and maintaining
 * a simple FIFO arrangement.  Realtime and Idle priority processes have
 * and explicit 0-31 priority which maps directly onto their class queue
 * index.  When a queue has something in it, the corresponding bit is
 * set in the queuebits variable, allowing a single read to determine
 * the state of all 32 queues and then a ffs() to find the first busy
 * queue.
 */
static struct rq bsd4_queues[NQS];
static struct rq bsd4_rtqueues[NQS];
static struct rq bsd4_idqueues[NQS];
static u_int32_t bsd4_queuebits;
static u_int32_t bsd4_rtqueuebits;
static u_int32_t bsd4_idqueuebits;
/* currently running a user process */
static cpumask_t bsd4_curprocmask = CPUMASK_INITIALIZER_ALLONES;
/* ready to accept a user process */
static cpumask_t bsd4_rdyprocmask;
static int       bsd4_runqcount;
static volatile int bsd4_scancpu;
static struct spinlock bsd4_spin;
static struct usched_bsd4_pcpu bsd4_pcpu[MAXCPU];
static struct sysctl_ctx_list usched_bsd4_sysctl_ctx;
static struct sysctl_oid *usched_bsd4_sysctl_tree;

/* Debug info exposed through debug.* sysctl */

SYSCTL_INT(_debug, OID_AUTO, bsd4_runqcount, CTLFLAG_RD,
           &bsd4_runqcount, 0,
           "Number of run queues");

static int usched_bsd4_debug = -1;
SYSCTL_INT(_debug, OID_AUTO, bsd4_scdebug, CTLFLAG_RW,
           &usched_bsd4_debug, 0,
           "Print debug information for this pid");

static int usched_bsd4_pid_debug = -1;
SYSCTL_INT(_debug, OID_AUTO, bsd4_pid_debug, CTLFLAG_RW,
           &usched_bsd4_pid_debug, 0,
           "Print KTR debug information for this pid");

/* Tunning usched_bsd4 - configurable through kern.usched_bsd4.* */
static int usched_bsd4_smt = 0;
static int usched_bsd4_cache_coherent = 0;
static int usched_bsd4_upri_affinity = 16; /* 32 queues - half-way */
static int usched_bsd4_queue_checks = 5;
static int usched_bsd4_stick_to_level = 0;
static long usched_bsd4_kicks;
static int usched_bsd4_rrinterval = (ESTCPUFREQ + 9) / 10;
static int usched_bsd4_decay = 8;
static int usched_bsd4_batch_time = 10;

/* KTR debug printings */

KTR_INFO_MASTER_EXTERN(usched);

#if !defined(KTR_USCHED_BSD4)
#define KTR_USCHED_BSD4 KTR_ALL
#endif

KTR_INFO(KTR_USCHED_BSD4, usched, bsd4_acquire_curproc_urw, 0,
    "USCHED_BSD4(bsd4_acquire_curproc in user_reseched_wanted "
    "after release: pid %d, cpuid %d, curr_cpuid %d)",
    pid_t pid, int cpuid, int curr);
KTR_INFO(KTR_USCHED_BSD4, usched, bsd4_acquire_curproc_before_loop, 0,
    "USCHED_BSD4(bsd4_acquire_curproc before loop: pid %d, cpuid %d, "
    "curr_cpuid %d)",
    pid_t pid, int cpuid, int curr);
KTR_INFO(KTR_USCHED_BSD4, usched, bsd4_acquire_curproc_not, 0,
    "USCHED_BSD4(bsd4_acquire_curproc couldn't acquire after "
    "bsd4_setrunqueue: pid %d, cpuid %d, curr_lp pid %d, curr_cpuid %d)",
    pid_t pid, int cpuid, pid_t curr_pid, int curr_cpuid);
KTR_INFO(KTR_USCHED_BSD4, usched, bsd4_acquire_curproc_switch, 0,
    "USCHED_BSD4(bsd4_acquire_curproc after lwkt_switch: pid %d, "
    "cpuid %d, curr_cpuid %d)",
    pid_t pid, int cpuid, int curr);

KTR_INFO(KTR_USCHED_BSD4, usched, bsd4_release_curproc, 0,
    "USCHED_BSD4(bsd4_release_curproc before select: pid %d, "
    "cpuid %d, curr_cpuid %d)",
    pid_t pid, int cpuid, int curr);

KTR_INFO(KTR_USCHED_BSD4, usched, bsd4_select_curproc, 0,
    "USCHED_BSD4(bsd4_release_curproc before select: pid %d, "
    "cpuid %d, old_pid %d, old_cpuid %d, curr_cpuid %d)",
    pid_t pid, int cpuid, pid_t old_pid, int old_cpuid, int curr);

KTR_INFO(KTR_USCHED_BSD4, usched, batchy_test_false, 0,
    "USCHED_BSD4(batchy_looser_pri_test false: pid %d, "
    "cpuid %d, verify_mask %lu)",
    pid_t pid, int cpuid, unsigned long mask);
KTR_INFO(KTR_USCHED_BSD4, usched, batchy_test_true, 0,
    "USCHED_BSD4(batchy_looser_pri_test true: pid %d, "
    "cpuid %d, verify_mask %lu)",
    pid_t pid, int cpuid, unsigned long mask);

KTR_INFO(KTR_USCHED_BSD4, usched, bsd4_setrunqueue_fc_smt, 0,
    "USCHED_BSD4(bsd4_setrunqueue free cpus smt: pid %d, cpuid %d, "
    "mask %lu, curr_cpuid %d)",
    pid_t pid, int cpuid, unsigned long mask, int curr);
KTR_INFO(KTR_USCHED_BSD4, usched, bsd4_setrunqueue_fc_non_smt, 0,
    "USCHED_BSD4(bsd4_setrunqueue free cpus check non_smt: pid %d, "
    "cpuid %d, mask %lu, curr_cpuid %d)",
    pid_t pid, int cpuid, unsigned long mask, int curr);
KTR_INFO(KTR_USCHED_BSD4, usched, bsd4_setrunqueue_rc, 0,
    "USCHED_BSD4(bsd4_setrunqueue running cpus check: pid %d, "
    "cpuid %d, mask %lu, curr_cpuid %d)",
    pid_t pid, int cpuid, unsigned long mask, int curr);
KTR_INFO(KTR_USCHED_BSD4, usched, bsd4_setrunqueue_found, 0,
    "USCHED_BSD4(bsd4_setrunqueue found cpu: pid %d, cpuid %d, "
    "mask %lu, found_cpuid %d, curr_cpuid %d)",
    pid_t pid, int cpuid, unsigned long mask, int found_cpuid, int curr);
KTR_INFO(KTR_USCHED_BSD4, usched, bsd4_setrunqueue_not_found, 0,
    "USCHED_BSD4(bsd4_setrunqueue not found cpu: pid %d, cpuid %d, "
    "try_cpuid %d, curr_cpuid %d)",
    pid_t pid, int cpuid, int try_cpuid, int curr);
KTR_INFO(KTR_USCHED_BSD4, usched, bsd4_setrunqueue_found_best_cpuid, 0,
    "USCHED_BSD4(bsd4_setrunqueue found cpu: pid %d, cpuid %d, "
    "mask %lu, found_cpuid %d, curr_cpuid %d)",
    pid_t pid, int cpuid, unsigned long mask, int found_cpuid, int curr);

KTR_INFO(KTR_USCHED_BSD4, usched, bsd4_chooseproc, 0,
    "USCHED_BSD4(chooseproc: pid %d, old_cpuid %d, curr_cpuid %d)",
    pid_t pid, int old_cpuid, int curr);
KTR_INFO(KTR_USCHED_BSD4, usched, chooseproc_cc, 0,
    "USCHED_BSD4(chooseproc_cc: pid %d, old_cpuid %d, curr_cpuid %d)",
    pid_t pid, int old_cpuid, int curr);
KTR_INFO(KTR_USCHED_BSD4, usched, chooseproc_cc_not_good, 0,
    "USCHED_BSD4(chooseproc_cc not good: pid %d, old_cpumask %lu, "
    "sibling_mask %lu, curr_cpumask %lu)",
    pid_t pid, unsigned long old_cpumask, unsigned long sibling_mask, unsigned long curr);
KTR_INFO(KTR_USCHED_BSD4, usched, chooseproc_cc_elected, 0,
    "USCHED_BSD4(chooseproc_cc elected: pid %d, old_cpumask %lu, "
    "sibling_mask %lu, curr_cpumask: %lu)",
    pid_t pid, unsigned long old_cpumask, unsigned long sibling_mask, unsigned long curr);

KTR_INFO(KTR_USCHED_BSD4, usched, sched_thread_no_process, 0,
    "USCHED_BSD4(sched_thread %d no process scheduled: pid %d, old_cpuid %d)",
    int id, pid_t pid, int cpuid);
KTR_INFO(KTR_USCHED_BSD4, usched, sched_thread_process, 0,
    "USCHED_BSD4(sched_thread %d process scheduled: pid %d, old_cpuid %d)",
    int id, pid_t pid, int cpuid);
KTR_INFO(KTR_USCHED_BSD4, usched, sched_thread_no_process_found, 0,
    "USCHED_BSD4(sched_thread %d no process found; tmpmask %lu)",
    int id, unsigned long tmpmask);

/*
 * Initialize the run queues at boot time.
 */
static void
bsd4_rqinit(void *dummy)
{
        int i;

        spin_init(&bsd4_spin, "bsd4rq");
        for (i = 0; i < NQS; i++) {
                TAILQ_INIT(&bsd4_queues[i]);
                TAILQ_INIT(&bsd4_rtqueues[i]);
                TAILQ_INIT(&bsd4_idqueues[i]);
        }
        ATOMIC_CPUMASK_NANDBIT(bsd4_curprocmask, 0);
}
SYSINIT(runqueue, SI_BOOT2_USCHED, SI_ORDER_FIRST, bsd4_rqinit, NULL);

/*
 * BSD4_ACQUIRE_CURPROC
 *
 * This function is called when the kernel intends to return to userland.
 * It is responsible for making the thread the current designated userland
 * thread for this cpu, blocking if necessary.
 *
 * The kernel will not depress our LWKT priority until after we return,
 * in case we have to shove over to another cpu.
 *
 * We must determine our thread's disposition before we switch away.  This
 * is very sensitive code.
 *
 * WARNING! THIS FUNCTION IS ALLOWED TO CAUSE THE CURRENT THREAD TO MIGRATE
 * TO ANOTHER CPU!  Because most of the kernel assumes that no migration will
 * occur, this function is called only under very controlled circumstances.
 *
 * MPSAFE
 */
static void
bsd4_acquire_curproc(struct lwp *lp)
{
        globaldata_t gd;
        bsd4_pcpu_t dd;
        thread_t td;
#if 0
        struct lwp *olp;
#endif

        /*
         * Make sure we aren't sitting on a tsleep queue.
         */
        td = lp->lwp_thread;
        crit_enter_quick(td);
        if (td->td_flags & TDF_TSLEEPQ)
                tsleep_remove(td);
        bsd4_recalculate_estcpu(lp);

        /*
         * If a reschedule was requested give another thread the
         * driver's seat.
         */
        if (user_resched_wanted()) {
                clear_user_resched();
                bsd4_release_curproc(lp);

                KTR_COND_LOG(usched_bsd4_acquire_curproc_urw,
                    lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
                    lp->lwp_proc->p_pid,
                    lp->lwp_thread->td_gd->gd_cpuid,
                    mycpu->gd_cpuid);
        }

        /*
         * Loop until we are the current user thread
         */
        gd = mycpu;
        dd = &bsd4_pcpu[gd->gd_cpuid];

        KTR_COND_LOG(usched_bsd4_acquire_curproc_before_loop,
            lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
            lp->lwp_proc->p_pid,
            lp->lwp_thread->td_gd->gd_cpuid,
            gd->gd_cpuid);

        do {
                /*
                 * Process any pending events and higher priority threads.
                 */
                lwkt_yield();

                /* This lwp is an outcast; force reschedule. */
                if (__predict_false(
                    CPUMASK_TESTBIT(lp->lwp_cpumask, gd->gd_cpuid) == 0)) {
                        bsd4_release_curproc(lp);
                        goto resched;
                }

                /*
                 * Become the currently scheduled user thread for this cpu
                 * if we can do so trivially.
                 *
                 * We can steal another thread's current thread designation
                 * on this cpu since if we are running that other thread
                 * must not be, so we can safely deschedule it.
                 */
                if (dd->uschedcp == lp) {
                        /*
                         * We are already the current lwp (hot path).
                         */
                        dd->upri = lp->lwp_priority;
                } else if (dd->uschedcp == NULL) {
                        /*
                         * We can trivially become the current lwp.
                         */
                        ATOMIC_CPUMASK_ORBIT(bsd4_curprocmask, gd->gd_cpuid);
                        dd->uschedcp = lp;
                        dd->upri = lp->lwp_priority;
                } else if (dd->upri > lp->lwp_priority) {
                        /*
                         * We can steal the current cpu's lwp designation
                         * away simply by replacing it.  The other thread
                         * will stall when it tries to return to userland.
                         */
                        dd->uschedcp = lp;
                        dd->upri = lp->lwp_priority;
                        /*
                        lwkt_deschedule(olp->lwp_thread);
                        bsd4_setrunqueue(olp);
                        */
                } else {
resched:
                        /*
                         * We cannot become the current lwp, place the lp
                         * on the bsd4 run-queue and deschedule ourselves.
                         *
                         * When we are reactivated we will have another
                         * chance.
                         */
                        lwkt_deschedule(lp->lwp_thread);

                        bsd4_setrunqueue(lp);

                        KTR_COND_LOG(usched_bsd4_acquire_curproc_not,
                            lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
                            lp->lwp_proc->p_pid,
                            lp->lwp_thread->td_gd->gd_cpuid,
                            dd->uschedcp->lwp_proc->p_pid,
                            gd->gd_cpuid);


                        lwkt_switch();

                        /*
                         * Reload after a switch or setrunqueue/switch possibly
                         * moved us to another cpu.
                         */
                        gd = mycpu;
                        dd = &bsd4_pcpu[gd->gd_cpuid];

                        KTR_COND_LOG(usched_bsd4_acquire_curproc_switch,
                            lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
                            lp->lwp_proc->p_pid,
                            lp->lwp_thread->td_gd->gd_cpuid,
                            gd->gd_cpuid);
                }
        } while (dd->uschedcp != lp);

        crit_exit_quick(td);
        KKASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0);
}

/*
 * BSD4_RELEASE_CURPROC
 *
 * This routine detaches the current thread from the userland scheduler,
 * usually because the thread needs to run or block in the kernel (at
 * kernel priority) for a while.
 *
 * This routine is also responsible for selecting a new thread to
 * make the current thread.
 *
 * NOTE: This implementation differs from the dummy example in that
 * bsd4_select_curproc() is able to select the current process, whereas
 * dummy_select_curproc() is not able to select the current process.
 * This means we have to NULL out uschedcp.
 *
 * Additionally, note that we may already be on a run queue if releasing
 * via the lwkt_switch() in bsd4_setrunqueue().
 *
 * MPSAFE
 */

static void
bsd4_release_curproc(struct lwp *lp)
{
        globaldata_t gd = mycpu;
        bsd4_pcpu_t dd = &bsd4_pcpu[gd->gd_cpuid];

        if (dd->uschedcp == lp) {
                crit_enter();
                KKASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0);

                KTR_COND_LOG(usched_bsd4_release_curproc,
                    lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
                    lp->lwp_proc->p_pid,
                    lp->lwp_thread->td_gd->gd_cpuid,
                    gd->gd_cpuid);

                dd->uschedcp = NULL;    /* don't let lp be selected */
                dd->upri = PRIBASE_NULL;
                ATOMIC_CPUMASK_NANDBIT(bsd4_curprocmask, gd->gd_cpuid);
                dd->old_uschedcp = lp;  /* used only for KTR debug prints */
                bsd4_select_curproc(gd);
                crit_exit();
        }
}

/*
 * BSD4_SELECT_CURPROC
 *
 * Select a new current process for this cpu and clear any pending user
 * reschedule request.  The cpu currently has no current process.
 *
 * This routine is also responsible for equal-priority round-robining,
 * typically triggered from bsd4_schedulerclock().  In our dummy example
 * all the 'user' threads are LWKT scheduled all at once and we just
 * call lwkt_switch().
 *
 * The calling process is not on the queue and cannot be selected.
 *
 * MPSAFE
 */
static
void
bsd4_select_curproc(globaldata_t gd)
{
        bsd4_pcpu_t dd = &bsd4_pcpu[gd->gd_cpuid];
        struct lwp *nlp;
        int cpuid = gd->gd_cpuid;

        crit_enter_gd(gd);

        spin_lock(&bsd4_spin);
        if(usched_bsd4_cache_coherent)
                nlp = bsd4_chooseproc_locked_cache_coherent(dd->uschedcp);
        else
                nlp = bsd4_chooseproc_locked(dd->uschedcp);

        if (nlp) {

                KTR_COND_LOG(usched_bsd4_select_curproc,
                    nlp->lwp_proc->p_pid == usched_bsd4_pid_debug,
                    nlp->lwp_proc->p_pid,
                    nlp->lwp_thread->td_gd->gd_cpuid,
                    dd->old_uschedcp->lwp_proc->p_pid,
                    dd->old_uschedcp->lwp_thread->td_gd->gd_cpuid,
                    gd->gd_cpuid);

                ATOMIC_CPUMASK_ORBIT(bsd4_curprocmask, cpuid);
                dd->upri = nlp->lwp_priority;
                dd->uschedcp = nlp;
                dd->rrcount = 0;                /* reset round robin */
                spin_unlock(&bsd4_spin);
                lwkt_acquire(nlp->lwp_thread);
                lwkt_schedule(nlp->lwp_thread);
        } else {
                spin_unlock(&bsd4_spin);
        }

#if 0
        } else if (bsd4_runqcount && CPUMASK_TESTBIT(bsd4_rdyprocmask, cpuid)) {
                ATOMIC_CPUMASK_NANDBIT(bsd4_rdyprocmask, cpuid);
                spin_unlock(&bsd4_spin);
                lwkt_schedule(dd->helper_thread);
        } else {
                spin_unlock(&bsd4_spin);
        }
#endif
        crit_exit_gd(gd);
}

/*
 * batchy_looser_pri_test() - determine if a process is batchy or not
 * relative to the other processes running in the system
 */
static int
bsd4_batchy_looser_pri_test(struct lwp* lp)
{
        cpumask_t mask;
        bsd4_pcpu_t other_dd;
        int cpu;

        /* Current running processes */
        mask = bsd4_curprocmask;
        CPUMASK_ANDMASK(mask, smp_active_mask);
        CPUMASK_ANDMASK(mask, usched_global_cpumask);

        while (CPUMASK_TESTNZERO(mask)) {
                cpu = BSFCPUMASK(mask);
                other_dd = &bsd4_pcpu[cpu];
                if (other_dd->upri - lp->lwp_priority > usched_bsd4_upri_affinity * PPQ) {

                        KTR_COND_LOG(usched_batchy_test_false,
                            lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
                            lp->lwp_proc->p_pid,
                            lp->lwp_thread->td_gd->gd_cpuid,
                            (unsigned long)CPUMASK_LOWMASK(mask));

                        return 0;
                }
                CPUMASK_NANDBIT(mask, cpu);
        }

        KTR_COND_LOG(usched_batchy_test_true,
            lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
            lp->lwp_proc->p_pid,
            lp->lwp_thread->td_gd->gd_cpuid,
            (unsigned long)CPUMASK_LOWMASK(mask));

        return 1;
}

/*
 *
 * BSD4_SETRUNQUEUE
 *
 * Place the specified lwp on the user scheduler's run queue.  This routine
 * must be called with the thread descheduled.  The lwp must be runnable.
 *
 * The thread may be the current thread as a special case.
 *
 * MPSAFE
 */
static void
bsd4_setrunqueue(struct lwp *lp)
{
        globaldata_t gd;
        bsd4_pcpu_t dd;
        int cpuid;
        cpumask_t mask;
        cpumask_t tmpmask;

        /*
         * First validate the process state relative to the current cpu.
         * We don't need the spinlock for this, just a critical section.
         * We are in control of the process.
         */
        crit_enter();
        KASSERT(lp->lwp_stat == LSRUN, ("setrunqueue: lwp not LSRUN"));
        KASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0,
            ("lwp %d/%d already on runq! flag %08x/%08x", lp->lwp_proc->p_pid,
             lp->lwp_tid, lp->lwp_proc->p_flags, lp->lwp_flags));
        KKASSERT((lp->lwp_thread->td_flags & TDF_RUNQ) == 0);

        /*
         * Note: gd and dd are relative to the target thread's last cpu,
         * NOT our current cpu.
         */
        gd = lp->lwp_thread->td_gd;
        dd = &bsd4_pcpu[gd->gd_cpuid];

        /*
         * This process is not supposed to be scheduled anywhere or assigned
         * as the current process anywhere.  Assert the condition.
         */
        KKASSERT(dd->uschedcp != lp);

        /*
         * XXX fixme.  Could be part of a remrunqueue/setrunqueue
         * operation when the priority is recalculated, so TDF_MIGRATING
         * may already be set.
         */
        if ((lp->lwp_thread->td_flags & TDF_MIGRATING) == 0)
                lwkt_giveaway(lp->lwp_thread);

        /*
         * We lose control of lp the moment we release the spinlock after
         * having placed lp on the queue.  i.e. another cpu could pick it
         * up and it could exit, or its priority could be further adjusted,
         * or something like that.
         */
        spin_lock(&bsd4_spin);
        bsd4_setrunqueue_locked(lp);
        lp->lwp_rebal_ticks = sched_ticks;

        /*
         * Kick the scheduler helper on one of the other cpu's
         * and request a reschedule if appropriate.
         *
         * NOTE: We check all cpus whos rdyprocmask is set.  First we
         *       look for cpus without designated lps, then we look for
         *       cpus with designated lps with a worse priority than our
         *       process.
         */
        ++bsd4_scancpu;

        if (usched_bsd4_smt) {

                /*
                 * SMT heuristic - Try to schedule on a free physical core.
                 * If no physical core found than choose the one that has
                 * an interactive thread.
                 */

                int best_cpuid = -1;
                int min_prio = MAXPRI * MAXPRI;
                int sibling;

                cpuid = (bsd4_scancpu & 0xFFFF) % ncpus;
                mask = bsd4_rdyprocmask;
                CPUMASK_NANDMASK(mask, bsd4_curprocmask);
                CPUMASK_ANDMASK(mask, lp->lwp_cpumask);
                CPUMASK_ANDMASK(mask, smp_active_mask);
                CPUMASK_ANDMASK(mask, usched_global_cpumask);

                KTR_COND_LOG(usched_bsd4_setrunqueue_fc_smt,
                    lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
                    lp->lwp_proc->p_pid,
                    lp->lwp_thread->td_gd->gd_cpuid,
                    (unsigned long)CPUMASK_LOWMASK(mask),
                    mycpu->gd_cpuid);

                while (CPUMASK_TESTNZERO(mask)) {
                        CPUMASK_ASSNBMASK(tmpmask, cpuid);
                        if (CPUMASK_TESTMASK(tmpmask, mask)) {
                                CPUMASK_ANDMASK(tmpmask, mask);
                                cpuid = BSFCPUMASK(tmpmask);
                        } else {
                                cpuid = BSFCPUMASK(mask);
                        }
                        gd = globaldata_find(cpuid);
                        dd = &bsd4_pcpu[cpuid];

                        if ((dd->upri & ~PPQMASK) >= (lp->lwp_priority & ~PPQMASK)) {
                                tmpmask = dd->cpunode->parent_node->members;
                                CPUMASK_NANDMASK(tmpmask, dd->cpunode->members);
                                CPUMASK_ANDMASK(tmpmask, mask);
                                if (CPUMASK_TESTNZERO(tmpmask)) {
                                        KTR_COND_LOG(usched_bsd4_setrunqueue_found,
                                            lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
                                            lp->lwp_proc->p_pid,
                                            lp->lwp_thread->td_gd->gd_cpuid,
                                            (unsigned long)CPUMASK_LOWMASK(mask),
                                            cpuid,
                                            mycpu->gd_cpuid);

                                        goto found;
                                } else {
                                        tmpmask =
                                            dd->cpunode->parent_node->members;
                                        CPUMASK_NANDMASK(tmpmask,
                                            dd->cpunode->members);
                                        sibling = BSFCPUMASK(tmpmask);
                                        if (min_prio >
                                            bsd4_pcpu[sibling].upri) {
                                                min_prio =
                                                        bsd4_pcpu[sibling].upri;
                                                best_cpuid = cpuid;
                                        }
                                }
                        }
                        CPUMASK_NANDBIT(mask, cpuid);
                }

                if (best_cpuid != -1) {
                        cpuid = best_cpuid;
                        gd = globaldata_find(cpuid);
                        dd = &bsd4_pcpu[cpuid];

                        KTR_COND_LOG(usched_bsd4_setrunqueue_found_best_cpuid,
                            lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
                            lp->lwp_proc->p_pid,
                            lp->lwp_thread->td_gd->gd_cpuid,
                            (unsigned long)CPUMASK_LOWMASK(mask),
                            cpuid,
                            mycpu->gd_cpuid);

                        goto found;
                }
        } else {
                /* Fallback to the original heuristic */
                cpuid = (bsd4_scancpu & 0xFFFF) % ncpus;
                mask = bsd4_rdyprocmask;
                CPUMASK_NANDMASK(mask, bsd4_curprocmask);
                CPUMASK_ANDMASK(mask, lp->lwp_cpumask);
                CPUMASK_ANDMASK(mask, smp_active_mask);
                CPUMASK_ANDMASK(mask, usched_global_cpumask);

                KTR_COND_LOG(usched_bsd4_setrunqueue_fc_non_smt,
                    lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
                    lp->lwp_proc->p_pid,
                    lp->lwp_thread->td_gd->gd_cpuid,
                    (unsigned long)CPUMASK_LOWMASK(mask),
                    mycpu->gd_cpuid);

                while (CPUMASK_TESTNZERO(mask)) {
                        CPUMASK_ASSNBMASK(tmpmask, cpuid);
                        if (CPUMASK_TESTMASK(tmpmask, mask)) {
                                CPUMASK_ANDMASK(tmpmask, mask);
                                cpuid = BSFCPUMASK(tmpmask);
                        } else {
                                cpuid = BSFCPUMASK(mask);
                        }
                        gd = globaldata_find(cpuid);
                        dd = &bsd4_pcpu[cpuid];

                        if ((dd->upri & ~PPQMASK) >=
                            (lp->lwp_priority & ~PPQMASK)) {
                                KTR_COND_LOG(usched_bsd4_setrunqueue_found,
                                    lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
                                    lp->lwp_proc->p_pid,
                                    lp->lwp_thread->td_gd->gd_cpuid,
                                    (unsigned long)CPUMASK_LOWMASK(mask),
                                    cpuid,
                                    mycpu->gd_cpuid);

                                goto found;
                        }
                        CPUMASK_NANDBIT(mask, cpuid);
                }
        }

        /*
         * Then cpus which might have a currently running lp
         */
        mask = bsd4_curprocmask;
        CPUMASK_ANDMASK(mask, bsd4_rdyprocmask);
        CPUMASK_ANDMASK(mask, lp->lwp_cpumask);
        CPUMASK_ANDMASK(mask, smp_active_mask);
        CPUMASK_ANDMASK(mask, usched_global_cpumask);

        KTR_COND_LOG(usched_bsd4_setrunqueue_rc,
            lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
            lp->lwp_proc->p_pid,
            lp->lwp_thread->td_gd->gd_cpuid,
            (unsigned long)CPUMASK_LOWMASK(mask),
            mycpu->gd_cpuid);

        while (CPUMASK_TESTNZERO(mask)) {
                CPUMASK_ASSNBMASK(tmpmask, cpuid);
                if (CPUMASK_TESTMASK(tmpmask, mask)) {
                        CPUMASK_ANDMASK(tmpmask, mask);
                        cpuid = BSFCPUMASK(tmpmask);
                } else {
                        cpuid = BSFCPUMASK(mask);
                }
                gd = globaldata_find(cpuid);
                dd = &bsd4_pcpu[cpuid];

                if ((dd->upri & ~PPQMASK) > (lp->lwp_priority & ~PPQMASK)) {
                        KTR_COND_LOG(usched_bsd4_setrunqueue_found,
                            lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
                            lp->lwp_proc->p_pid,
                            lp->lwp_thread->td_gd->gd_cpuid,
                            (unsigned long)CPUMASK_LOWMASK(mask),
                            cpuid,
                            mycpu->gd_cpuid);

                        goto found;
                }
                CPUMASK_NANDBIT(mask, cpuid);
        }

        /*
         * If we cannot find a suitable cpu we reload from bsd4_scancpu
         * and round-robin.  Other cpus will pickup as they release their
         * current lwps or become ready.
         *
         * Avoid a degenerate system lockup case if usched_global_cpumask
         * is set to 0 or otherwise does not cover lwp_cpumask.
         *
         * We only kick the target helper thread in this case, we do not
         * set the user resched flag because
         */
        cpuid = (bsd4_scancpu & 0xFFFF) % ncpus;
        if (CPUMASK_TESTBIT(lp->lwp_cpumask, cpuid) == 0)
                cpuid = BSFCPUMASK(lp->lwp_cpumask);
        else if (CPUMASK_TESTBIT(usched_global_cpumask, cpuid) == 0)
                cpuid = 0;
        gd = globaldata_find(cpuid);
        dd = &bsd4_pcpu[cpuid];

        KTR_COND_LOG(usched_bsd4_setrunqueue_not_found,
            lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
            lp->lwp_proc->p_pid,
            lp->lwp_thread->td_gd->gd_cpuid,
            cpuid,
            mycpu->gd_cpuid);

found:
        if (gd == mycpu) {
                spin_unlock(&bsd4_spin);
                if ((dd->upri & ~PPQMASK) > (lp->lwp_priority & ~PPQMASK)) {
                        if (dd->uschedcp == NULL) {
                                wakeup_mycpu(dd->helper_thread);
                        } else {
                                need_user_resched();
                        }
                }
        } else {
                ATOMIC_CPUMASK_NANDBIT(bsd4_rdyprocmask, cpuid);
                spin_unlock(&bsd4_spin);
                if ((dd->upri & ~PPQMASK) > (lp->lwp_priority & ~PPQMASK))
                        lwkt_send_ipiq(gd, bsd4_need_user_resched_remote, NULL);
                else
                        wakeup(dd->helper_thread);
        }
        crit_exit();
}

/*
 * This routine is called from a systimer IPI.  It MUST be MP-safe and
 * the BGL IS NOT HELD ON ENTRY.  This routine is called at ESTCPUFREQ on
 * each cpu.
 *
 * This routine is called on every sched tick.  If the currently running
 * thread belongs to this scheduler it will be called with a non-NULL lp,
 * otherwise it will be called with a NULL lp.
 *
 * MPSAFE
 */
static
void
bsd4_schedulerclock(struct lwp *lp, sysclock_t period, sysclock_t cpstamp)
{
        globaldata_t gd = mycpu;
        bsd4_pcpu_t dd = &bsd4_pcpu[gd->gd_cpuid];

        /*
         * No impl if no lp running.
         */
        if (lp == NULL)
                return;

        /*
         * Do we need to round-robin?  We round-robin 10 times a second.
         * This should only occur for cpu-bound batch processes.
         */
        if (++dd->rrcount >= usched_bsd4_rrinterval) {
                dd->rrcount = 0;
                need_user_resched();
        }

        /*
         * Adjust estcpu upward using a real time equivalent calculation.
         */
        lp->lwp_estcpu = ESTCPULIM(lp->lwp_estcpu + ESTCPUMAX / ESTCPUFREQ + 1);

        /*
         * Spinlocks also hold a critical section so there should not be
         * any active.
         */
        KKASSERT(gd->gd_spinlocks == 0);

        bsd4_resetpriority(lp);
}

/*
 * Called from acquire and from kern_synch's one-second timer (one of the
 * callout helper threads) with a critical section held.
 *
 * Decay p_estcpu based on the number of ticks we haven't been running
 * and our p_nice.  As the load increases each process observes a larger
 * number of idle ticks (because other processes are running in them).
 * This observation leads to a larger correction which tends to make the
 * system more 'batchy'.
 *
 * Note that no recalculation occurs for a process which sleeps and wakes
 * up in the same tick.  That is, a system doing thousands of context
 * switches per second will still only do serious estcpu calculations
 * ESTCPUFREQ times per second.
 *
 * MPSAFE
 */
static
void
bsd4_recalculate_estcpu(struct lwp *lp)
{
        globaldata_t gd = mycpu;
        sysclock_t cpbase;
        sysclock_t ttlticks;
        int estcpu;
        int decay_factor;

        /*
         * We have to subtract periodic to get the last schedclock
         * timeout time, otherwise we would get the upcoming timeout.
         * Keep in mind that a process can migrate between cpus and
         * while the scheduler clock should be very close, boundary
         * conditions could lead to a small negative delta.
         */
        cpbase = gd->gd_schedclock.time - gd->gd_schedclock.periodic;

        if (lp->lwp_slptime > 1) {
                /*
                 * Too much time has passed, do a coarse correction.
                 */
                lp->lwp_estcpu = lp->lwp_estcpu >> 1;
                bsd4_resetpriority(lp);
                lp->lwp_cpbase = cpbase;
                lp->lwp_cpticks = 0;
                lp->lwp_batch -= ESTCPUFREQ;
                if (lp->lwp_batch < 0)
                        lp->lwp_batch = 0;
        } else if (lp->lwp_cpbase != cpbase) {
                /*
                 * Adjust estcpu if we are in a different tick.  Don't waste
                 * time if we are in the same tick.
                 *
                 * First calculate the number of ticks in the measurement
                 * interval.  The ttlticks calculation can wind up 0 due to
                 * a bug in the handling of lwp_slptime  (as yet not found),
                 * so make sure we do not get a divide by 0 panic.
                 */
                ttlticks = (cpbase - lp->lwp_cpbase) /
                           gd->gd_schedclock.periodic;
                if ((ssysclock_t)ttlticks < 0) {
                        ttlticks = 0;
                        lp->lwp_cpbase = cpbase;
                }
                if (ttlticks == 0)
                        return;
                updatepcpu(lp, lp->lwp_cpticks, ttlticks);

                /*
                 * Calculate the percentage of one cpu used factoring in ncpus
                 * and the load and adjust estcpu.  Handle degenerate cases
                 * by adding 1 to bsd4_runqcount.
                 *
                 * estcpu is scaled by ESTCPUMAX.
                 *
                 * bsd4_runqcount is the excess number of user processes
                 * that cannot be immediately scheduled to cpus.  We want
                 * to count these as running to avoid range compression
                 * in the base calculation (which is the actual percentage
                 * of one cpu used).
                 */
                estcpu = (lp->lwp_cpticks * ESTCPUMAX) *
                         (bsd4_runqcount + ncpus) / (ncpus * ttlticks);

                /*
                 * If estcpu is > 50% we become more batch-like
                 * If estcpu is <= 50% we become less batch-like
                 *
                 * It takes 30 cpu seconds to traverse the entire range.
                 */
                if (estcpu > ESTCPUMAX / 2) {
                        lp->lwp_batch += ttlticks;
                        if (lp->lwp_batch > BATCHMAX)
                                lp->lwp_batch = BATCHMAX;
                } else {
                        lp->lwp_batch -= ttlticks;
                        if (lp->lwp_batch < 0)
                                lp->lwp_batch = 0;
                }

                if (usched_bsd4_debug == lp->lwp_proc->p_pid) {
                        kprintf("pid %d lwp %p estcpu %3d %3d bat %d cp %d/%d",
                                lp->lwp_proc->p_pid, lp,
                                estcpu, lp->lwp_estcpu,
                                lp->lwp_batch,
                                lp->lwp_cpticks, ttlticks);
                }

                /*
                 * Adjust lp->lwp_esetcpu.  The decay factor determines how
                 * quickly lwp_estcpu collapses to its realtime calculation.
                 * A slower collapse gives us a more accurate number but
                 * can cause a cpu hog to eat too much cpu before the
                 * scheduler decides to downgrade it.
                 *
                 * NOTE: p_nice is accounted for in bsd4_resetpriority(),
                 *       and not here, but we must still ensure that a
                 *       cpu-bound nice -20 process does not completely
                 *       override a cpu-bound nice +20 process.
                 *
                 * NOTE: We must use ESTCPULIM() here to deal with any
                 *       overshoot.
                 */
                decay_factor = usched_bsd4_decay;
                if (decay_factor < 1)
                        decay_factor = 1;
                if (decay_factor > 1024)
                        decay_factor = 1024;

                lp->lwp_estcpu = ESTCPULIM(
                        (lp->lwp_estcpu * decay_factor + estcpu) /
                        (decay_factor + 1));

                if (usched_bsd4_debug == lp->lwp_proc->p_pid)
                        kprintf(" finalestcpu %d\n", lp->lwp_estcpu);
                bsd4_resetpriority(lp);
                lp->lwp_cpbase += ttlticks * gd->gd_schedclock.periodic;
                lp->lwp_cpticks = 0;
        }
}

/*
 * Compute the priority of a process when running in user mode.
 * Arrange to reschedule if the resulting priority is better
 * than that of the current process.
 *
 * This routine may be called with any process.
 *
 * This routine is called by fork1() for initial setup with the process
 * of the run queue, and also may be called normally with the process on or
 * off the run queue.
 *
 * MPSAFE
 */
static void
bsd4_resetpriority(struct lwp *lp)
{
        bsd4_pcpu_t dd;
        int newpriority;
        u_short newrqtype;
        int reschedcpu;
        int checkpri;
        int estcpu;

        /*
         * Calculate the new priority and queue type
         */
        crit_enter();
        spin_lock(&bsd4_spin);

        newrqtype = lp->lwp_rtprio.type;

        switch(newrqtype) {
        case RTP_PRIO_REALTIME:
        case RTP_PRIO_FIFO:
                newpriority = PRIBASE_REALTIME +
                             (lp->lwp_rtprio.prio & PRIMASK);
                break;
        case RTP_PRIO_NORMAL:
                /*
                 * Detune estcpu based on batchiness.  lwp_batch ranges
                 * from 0 to  BATCHMAX.  Limit estcpu for the sake of
                 * the priority calculation to between 50% and 100%.
                 */
                estcpu = lp->lwp_estcpu * (lp->lwp_batch + BATCHMAX) /
                         (BATCHMAX * 2);

                /*
                 * p_nice piece         Adds (0-40) * 2         0-80
                 * estcpu               Adds 16384  * 4 / 512   0-128
                 */
                newpriority = (lp->lwp_proc->p_nice - PRIO_MIN) * PPQ / NICEPPQ;
                newpriority += estcpu * PPQ / ESTCPUPPQ;
                newpriority = newpriority * MAXPRI / (PRIO_RANGE * PPQ /
                              NICEPPQ + ESTCPUMAX * PPQ / ESTCPUPPQ);
                newpriority = PRIBASE_NORMAL + (newpriority & PRIMASK);
                break;
        case RTP_PRIO_IDLE:
                newpriority = PRIBASE_IDLE + (lp->lwp_rtprio.prio & PRIMASK);
                break;
        case RTP_PRIO_THREAD:
                newpriority = PRIBASE_THREAD + (lp->lwp_rtprio.prio & PRIMASK);
                break;
        default:
                panic("Bad RTP_PRIO %d", newrqtype);
                /* NOT REACHED */
        }

        /*
         * The newpriority incorporates the queue type so do a simple masked
         * check to determine if the process has moved to another queue.  If
         * it has, and it is currently on a run queue, then move it.
         *
         * td_upri has normal sense (higher values are more desireable), so
         * negate it.
         */
        lp->lwp_thread->td_upri = -(newpriority & ~PPQMASK);
        if ((lp->lwp_priority ^ newpriority) & ~PPQMASK) {
                lp->lwp_priority = newpriority;
                if (lp->lwp_mpflags & LWP_MP_ONRUNQ) {
                        bsd4_remrunqueue_locked(lp);
                        lp->lwp_rqtype = newrqtype;
                        lp->lwp_rqindex = (newpriority & PRIMASK) / PPQ;
                        bsd4_setrunqueue_locked(lp);
                        checkpri = 1;
                } else {
                        lp->lwp_rqtype = newrqtype;
                        lp->lwp_rqindex = (newpriority & PRIMASK) / PPQ;
                        checkpri = 0;
                }
                reschedcpu = lp->lwp_thread->td_gd->gd_cpuid;
        } else {
                lp->lwp_priority = newpriority;
                reschedcpu = -1;
                checkpri = 1;
        }

        /*
         * Determine if we need to reschedule the target cpu.  This only
         * occurs if the LWP is already on a scheduler queue, which means
         * that idle cpu notification has already occured.  At most we
         * need only issue a need_user_resched() on the appropriate cpu.
         *
         * The LWP may be owned by a CPU different from the current one,
         * in which case dd->uschedcp may be modified without an MP lock
         * or a spinlock held.  The worst that happens is that the code
         * below causes a spurious need_user_resched() on the target CPU
         * and dd->pri to be wrong for a short period of time, both of
         * which are harmless.
         *
         * If checkpri is 0 we are adjusting the priority of the current
         * process, possibly higher (less desireable), so ignore the upri
         * check which will fail in that case.
         */
        if (reschedcpu >= 0) {
                dd = &bsd4_pcpu[reschedcpu];
                if (CPUMASK_TESTBIT(bsd4_rdyprocmask, reschedcpu) &&
                    (checkpri == 0 ||
                     (dd->upri & ~PRIMASK) > (lp->lwp_priority & ~PRIMASK))) {
                        if (reschedcpu == mycpu->gd_cpuid) {
                                spin_unlock(&bsd4_spin);
                                need_user_resched();
                        } else {
                                spin_unlock(&bsd4_spin);
                                ATOMIC_CPUMASK_NANDBIT(bsd4_rdyprocmask,
                                                       reschedcpu);
                                lwkt_send_ipiq(lp->lwp_thread->td_gd,
                                               bsd4_need_user_resched_remote,
                                               NULL);
                        }
                } else {
                        spin_unlock(&bsd4_spin);
                }
        } else {
                spin_unlock(&bsd4_spin);
        }
        crit_exit();
}

/*
 * MPSAFE
 */
static
void
bsd4_yield(struct lwp *lp)
{
#if 0
        /* FUTURE (or something similar) */
        switch(lp->lwp_rqtype) {
        case RTP_PRIO_NORMAL:
                lp->lwp_estcpu = ESTCPULIM(lp->lwp_estcpu + ESTCPUINCR);
                break;
        default:
                break;
        }
#endif
        need_user_resched();
}

static
void
bsd4_changedcpu(struct lwp *lp __unused)
{
}

/*
 * Called from fork1() when a new child process is being created.
 *
 * Give the child process an initial estcpu that is more batch then
 * its parent and dock the parent for the fork (but do not
 * reschedule the parent).   This comprises the main part of our batch
 * detection heuristic for both parallel forking and sequential execs.
 *
 * XXX lwp should be "spawning" instead of "forking"
 *
 * MPSAFE
 */
static void
bsd4_forking(struct lwp *plp, struct lwp *lp)
{
        /*
         * Put the child 4 queue slots (out of 32) higher than the parent
         * (less desireable than the parent).
         */
        lp->lwp_estcpu = ESTCPULIM(plp->lwp_estcpu + ESTCPUPPQ * 4);

        /*
         * The batch status of children always starts out centerline
         * and will inch-up or inch-down as appropriate.  It takes roughly
         * ~15 seconds of >50% cpu to hit the limit.
         */
        lp->lwp_batch = BATCHMAX / 2;

        /*
         * Dock the parent a cost for the fork, protecting us from fork
         * bombs.  If the parent is forking quickly make the child more
         * batchy.
         */
        plp->lwp_estcpu = ESTCPULIM(plp->lwp_estcpu + ESTCPUPPQ / 16);
}

/*
 * Called when a lwp is being removed from this scheduler, typically
 * during lwp_exit().
 */
static void
bsd4_exiting(struct lwp *lp, struct proc *child_proc)
{
}

static void
bsd4_uload_update(struct lwp *lp)
{
}

/*
 * chooseproc() is called when a cpu needs a user process to LWKT schedule,
 * it selects a user process and returns it.  If chklp is non-NULL and chklp
 * has a better or equal priority then the process that would otherwise be
 * chosen, NULL is returned.
 *
 * Until we fix the RUNQ code the chklp test has to be strict or we may
 * bounce between processes trying to acquire the current process designation.
 *
 * MPSAFE - must be called with bsd4_spin exclusive held.  The spinlock is
 *          left intact through the entire routine.
 */
static
struct lwp *
bsd4_chooseproc_locked(struct lwp *chklp)
{
        struct lwp *lp;
        struct rq *q;
        u_int32_t *which, *which2;
        u_int32_t pri;
        u_int32_t rtqbits;
        u_int32_t tsqbits;
        u_int32_t idqbits;
        cpumask_t cpumask;

        rtqbits = bsd4_rtqueuebits;
        tsqbits = bsd4_queuebits;
        idqbits = bsd4_idqueuebits;
        cpumask = mycpu->gd_cpumask;


again:
        if (rtqbits) {
                pri = bsfl(rtqbits);
                q = &bsd4_rtqueues[pri];
                which = &bsd4_rtqueuebits;
                which2 = &rtqbits;
        } else if (tsqbits) {
                pri = bsfl(tsqbits);
                q = &bsd4_queues[pri];
                which = &bsd4_queuebits;
                which2 = &tsqbits;
        } else if (idqbits) {
                pri = bsfl(idqbits);
                q = &bsd4_idqueues[pri];
                which = &bsd4_idqueuebits;
                which2 = &idqbits;
        } else {
                return NULL;
        }
        lp = TAILQ_FIRST(q);
        KASSERT(lp, ("chooseproc: no lwp on busy queue"));

        while (CPUMASK_TESTMASK(lp->lwp_cpumask, cpumask) == 0) {
                lp = TAILQ_NEXT(lp, lwp_procq);
                if (lp == NULL) {
                        *which2 &= ~(1 << pri);
                        goto again;
                }
        }

        /*
         * If the passed lwp <chklp> is reasonably close to the selected
         * lwp <lp>, return NULL (indicating that <chklp> should be kept).
         *
         * Note that we must error on the side of <chklp> to avoid bouncing
         * between threads in the acquire code.
         */
        if (chklp) {
                if (chklp->lwp_priority < lp->lwp_priority + PPQ)
                        return(NULL);
        }

        /*
         * If the chosen lwp does not reside on this cpu spend a few
         * cycles looking for a better candidate at the same priority level.
         * This is a fallback check, setrunqueue() tries to wakeup the
         * correct cpu and is our front-line affinity.
         */
        if (lp->lwp_thread->td_gd != mycpu &&
            (chklp = TAILQ_NEXT(lp, lwp_procq)) != NULL
        ) {
                if (chklp->lwp_thread->td_gd == mycpu) {
                        lp = chklp;
                }
        }

        KTR_COND_LOG(usched_bsd4_chooseproc,
            lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
            lp->lwp_proc->p_pid,
            lp->lwp_thread->td_gd->gd_cpuid,
            mycpu->gd_cpuid);

        TAILQ_REMOVE(q, lp, lwp_procq);
        --bsd4_runqcount;
        if (TAILQ_EMPTY(q))
                *which &= ~(1 << pri);
        KASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) != 0, ("not on runq6!"));
        atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ);

        return lp;
}

/*
 * chooseproc() - with a cache coherence heuristic. Try to pull a process that
 * has its home on the current CPU> If the process doesn't have its home here
 * and is a batchy one (see batcy_looser_pri_test), we can wait for a
 * sched_tick, may be its home will become free and pull it in. Anyway,
 * we can't wait more than one tick. If that tick expired, we pull in that
 * process, no matter what.
 */
static
struct lwp *
bsd4_chooseproc_locked_cache_coherent(struct lwp *chklp)
{
        struct lwp *lp;
        struct rq *q;
        u_int32_t *which, *which2;
        u_int32_t pri;
        u_int32_t checks;
        u_int32_t rtqbits;
        u_int32_t tsqbits;
        u_int32_t idqbits;
        cpumask_t cpumask;

        struct lwp * min_level_lwp = NULL;
        struct rq *min_q = NULL;
        cpumask_t siblings;
        cpu_node_t* cpunode = NULL;
        u_int32_t min_level = MAXCPU;   /* number of levels < MAXCPU */
        u_int32_t *min_which = NULL;
        u_int32_t min_pri = 0;
        u_int32_t level = 0;

        rtqbits = bsd4_rtqueuebits;
        tsqbits = bsd4_queuebits;
        idqbits = bsd4_idqueuebits;
        cpumask = mycpu->gd_cpumask;

        /* Get the mask coresponding to the sysctl configured level */
        cpunode = bsd4_pcpu[mycpu->gd_cpuid].cpunode;
        level = usched_bsd4_stick_to_level;
        while (level) {
                cpunode = cpunode->parent_node;
                level--;
        }
        /* The cpus which can ellect a process */
        siblings = cpunode->members;
        checks = 0;

again:
        if (rtqbits) {
                pri = bsfl(rtqbits);
                q = &bsd4_rtqueues[pri];
                which = &bsd4_rtqueuebits;
                which2 = &rtqbits;
        } else if (tsqbits) {
                pri = bsfl(tsqbits);
                q = &bsd4_queues[pri];
                which = &bsd4_queuebits;
                which2 = &tsqbits;
        } else if (idqbits) {
                pri = bsfl(idqbits);
                q = &bsd4_idqueues[pri];
                which = &bsd4_idqueuebits;
                which2 = &idqbits;
        } else {
                /*
                 * No more left and we didn't reach the checks limit.
                 */
                bsd4_kick_helper(min_level_lwp);
                return NULL;
        }
        lp = TAILQ_FIRST(q);
        KASSERT(lp, ("chooseproc: no lwp on busy queue"));

        /*
         * Limit the number of checks/queue to a configurable value to
         * minimize the contention (we are in a locked region
         */
        while (checks < usched_bsd4_queue_checks) {
                if (CPUMASK_TESTMASK(lp->lwp_cpumask, cpumask) == 0 ||
                    (CPUMASK_TESTMASK(siblings,
                                      lp->lwp_thread->td_gd->gd_cpumask) == 0 &&
                      (lp->lwp_rebal_ticks == sched_ticks ||
                       lp->lwp_rebal_ticks == (int)(sched_ticks - 1)) &&
                      bsd4_batchy_looser_pri_test(lp))) {

                        KTR_COND_LOG(usched_chooseproc_cc_not_good,
                            lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
                            lp->lwp_proc->p_pid,
                            (unsigned long)CPUMASK_LOWMASK(
                                        lp->lwp_thread->td_gd->gd_cpumask),
                            (unsigned long)CPUMASK_LOWMASK(siblings),
                            (unsigned long)CPUMASK_LOWMASK(cpumask));

                        cpunode = bsd4_pcpu[lp->lwp_thread->td_gd->gd_cpuid].cpunode;
                        level = 0;
                        while (cpunode) {
                                if (CPUMASK_TESTMASK(cpunode->members,
                                                     cpumask)) {
                                        break;
                                }
                                cpunode = cpunode->parent_node;
                                level++;
                        }
                        if (level < min_level ||
                            (level == min_level && min_level_lwp &&
                             lp->lwp_priority < min_level_lwp->lwp_priority)) {
                                bsd4_kick_helper(min_level_lwp);
                                min_level_lwp = lp;
                                min_level = level;
                                min_q = q;
                                min_which = which;
                                min_pri = pri;
                        } else {
                                bsd4_kick_helper(lp);
                        }
                        lp = TAILQ_NEXT(lp, lwp_procq);
                        if (lp == NULL) {
                                *which2 &= ~(1 << pri);
                                goto again;
                        }
                } else {
                        KTR_COND_LOG(usched_chooseproc_cc_elected,
                            lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
                            lp->lwp_proc->p_pid,
                            (unsigned long)CPUMASK_LOWMASK(
                                        lp->lwp_thread->td_gd->gd_cpumask),
                            (unsigned long)CPUMASK_LOWMASK(siblings),
                            (unsigned long)CPUMASK_LOWMASK(cpumask));

                        goto found;
                }
                ++checks;
        }

        /*
         * Checks exhausted, we tried to defer too many threads, so schedule
         * the best of the worst.
         */
        lp = min_level_lwp;
        q = min_q;
        which = min_which;
        pri = min_pri;
        KASSERT(lp, ("chooseproc: at least the first lp was good"));

found:

        /*
         * If the passed lwp <chklp> is reasonably close to the selected
         * lwp <lp>, return NULL (indicating that <chklp> should be kept).
         *
         * Note that we must error on the side of <chklp> to avoid bouncing
         * between threads in the acquire code.
         */
        if (chklp) {
                if (chklp->lwp_priority < lp->lwp_priority + PPQ) {
                        bsd4_kick_helper(lp);
                        return(NULL);
                }
        }

        KTR_COND_LOG(usched_chooseproc_cc,
            lp->lwp_proc->p_pid == usched_bsd4_pid_debug,
            lp->lwp_proc->p_pid,
            lp->lwp_thread->td_gd->gd_cpuid,
            mycpu->gd_cpuid);

        TAILQ_REMOVE(q, lp, lwp_procq);
        --bsd4_runqcount;
        if (TAILQ_EMPTY(q))
                *which &= ~(1 << pri);
        KASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) != 0, ("not on runq6!"));
        atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ);

        return lp;
}

/*
 * If we aren't willing to schedule a ready process on our cpu, give it's
 * target cpu a kick rather than wait for the next tick.
 *
 * Called with bsd4_spin held.
 */
static
void
bsd4_kick_helper(struct lwp *lp)
{
        globaldata_t gd;
        bsd4_pcpu_t dd;
        cpumask_t tmpmask;

        if (lp == NULL)
                return;
        gd = lp->lwp_thread->td_gd;
        dd = &bsd4_pcpu[gd->gd_cpuid];

        tmpmask = smp_active_mask;
        CPUMASK_ANDMASK(tmpmask, usched_global_cpumask);
        CPUMASK_ANDMASK(tmpmask, bsd4_rdyprocmask);
        CPUMASK_ANDMASK(tmpmask, gd->gd_cpumask);
        if (CPUMASK_TESTZERO(tmpmask))
                return;

        ++usched_bsd4_kicks;
        ATOMIC_CPUMASK_NANDBIT(bsd4_rdyprocmask, gd->gd_cpuid);
        if ((dd->upri & ~PPQMASK) > (lp->lwp_priority & ~PPQMASK)) {
                lwkt_send_ipiq(gd, bsd4_need_user_resched_remote, NULL);
        } else {
                wakeup(dd->helper_thread);
        }
}

static
void
bsd4_need_user_resched_remote(void *dummy)
{
        globaldata_t gd = mycpu;
        bsd4_pcpu_t  dd = &bsd4_pcpu[gd->gd_cpuid];

        need_user_resched();

        /* Call wakeup_mycpu to avoid sending IPIs to other CPUs */
        wakeup_mycpu(dd->helper_thread);
}

/*
 * bsd4_remrunqueue_locked() removes a given process from the run queue
 * that it is on, clearing the queue busy bit if it becomes empty.
 *
 * Note that user process scheduler is different from the LWKT schedule.
 * The user process scheduler only manages user processes but it uses LWKT
 * underneath, and a user process operating in the kernel will often be
 * 'released' from our management.
 *
 * MPSAFE - bsd4_spin must be held exclusively on call
 */
static void
bsd4_remrunqueue_locked(struct lwp *lp)
{
        struct rq *q;
        u_int32_t *which;
        u_int8_t pri;

        KKASSERT(lp->lwp_mpflags & LWP_MP_ONRUNQ);
        atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ);
        --bsd4_runqcount;
        KKASSERT(bsd4_runqcount >= 0);

        pri = lp->lwp_rqindex;
        switch(lp->lwp_rqtype) {
        case RTP_PRIO_NORMAL:
                q = &bsd4_queues[pri];
                which = &bsd4_queuebits;
                break;
        case RTP_PRIO_REALTIME:
        case RTP_PRIO_FIFO:
                q = &bsd4_rtqueues[pri];
                which = &bsd4_rtqueuebits;
                break;
        case RTP_PRIO_IDLE:
                q = &bsd4_idqueues[pri];
                which = &bsd4_idqueuebits;
                break;
        default:
                panic("remrunqueue: invalid rtprio type");
                /* NOT REACHED */
        }
        TAILQ_REMOVE(q, lp, lwp_procq);
        if (TAILQ_EMPTY(q)) {
                KASSERT((*which & (1 << pri)) != 0,
                        ("remrunqueue: remove from empty queue"));
                *which &= ~(1 << pri);
        }
}

/*
 * bsd4_setrunqueue_locked()
 *
 * Add a process whos rqtype and rqindex had previously been calculated
 * onto the appropriate run queue.   Determine if the addition requires
 * a reschedule on a cpu and return the cpuid or -1.
 *
 * NOTE: Lower priorities are better priorities.
 *
 * MPSAFE - bsd4_spin must be held exclusively on call
 */
static void
bsd4_setrunqueue_locked(struct lwp *lp)
{
        struct rq *q;
        u_int32_t *which;
        int pri;

        KKASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0);
        atomic_set_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ);
        ++bsd4_runqcount;

        pri = lp->lwp_rqindex;

        switch(lp->lwp_rqtype) {
        case RTP_PRIO_NORMAL:
                q = &bsd4_queues[pri];
                which = &bsd4_queuebits;
                break;
        case RTP_PRIO_REALTIME:
        case RTP_PRIO_FIFO:
                q = &bsd4_rtqueues[pri];
                which = &bsd4_rtqueuebits;
                break;
        case RTP_PRIO_IDLE:
                q = &bsd4_idqueues[pri];
                which = &bsd4_idqueuebits;
                break;
        default:
                panic("remrunqueue: invalid rtprio type");
                /* NOT REACHED */
        }

        /*
         * Add to the correct queue and set the appropriate bit.  If no
         * lower priority (i.e. better) processes are in the queue then
         * we want a reschedule, calculate the best cpu for the job.
         *
         * Always run reschedules on the LWPs original cpu.
         */
        TAILQ_INSERT_TAIL(q, lp, lwp_procq);
        *which |= 1 << pri;
}

/*
 * For SMP systems a user scheduler helper thread is created for each
 * cpu and is used to allow one cpu to wakeup another for the purposes of
 * scheduling userland threads from setrunqueue().
 *
 * UP systems do not need the helper since there is only one cpu.
 *
 * We can't use the idle thread for this because we might block.
 * Additionally, doing things this way allows us to HLT idle cpus
 * on MP systems.
 *
 * MPSAFE
 */
static void
sched_thread(void *dummy)
{
    globaldata_t gd;
    bsd4_pcpu_t  dd;
    bsd4_pcpu_t  tmpdd;
    struct lwp *nlp;
    cpumask_t mask;
    int cpuid;
    cpumask_t tmpmask;
    int tmpid;

    gd = mycpu;
    cpuid = gd->gd_cpuid;       /* doesn't change */
    mask = gd->gd_cpumask;      /* doesn't change */
    dd = &bsd4_pcpu[cpuid];

    /*
     * Since we are woken up only when no user processes are scheduled
     * on a cpu, we can run at an ultra low priority.
     */
    lwkt_setpri_self(TDPRI_USER_SCHEDULER);

    tsleep(dd->helper_thread, 0, "sched_thread_sleep", 0);

    for (;;) {
        /*
         * We use the LWKT deschedule-interlock trick to avoid racing
         * bsd4_rdyprocmask.  This means we cannot block through to the
         * manual lwkt_switch() call we make below.
         */
        crit_enter_gd(gd);
        tsleep_interlock(dd->helper_thread, 0);
        spin_lock(&bsd4_spin);
        ATOMIC_CPUMASK_ORMASK(bsd4_rdyprocmask, mask);

        clear_user_resched();   /* This satisfied the reschedule request */
        dd->rrcount = 0;        /* Reset the round-robin counter */

        if (CPUMASK_TESTMASK(bsd4_curprocmask, mask) == 0) {
                /*
                 * No thread is currently scheduled.
                 */
                KKASSERT(dd->uschedcp == NULL);
                if ((nlp = bsd4_chooseproc_locked(NULL)) != NULL) {
                        KTR_COND_LOG(usched_sched_thread_no_process,
                            nlp->lwp_proc->p_pid == usched_bsd4_pid_debug,
                            gd->gd_cpuid,
                            nlp->lwp_proc->p_pid,
                            nlp->lwp_thread->td_gd->gd_cpuid);

                        ATOMIC_CPUMASK_ORMASK(bsd4_curprocmask, mask);
                        dd->upri = nlp->lwp_priority;
                        dd->uschedcp = nlp;
                        dd->rrcount = 0;        /* reset round robin */
                        spin_unlock(&bsd4_spin);
                        lwkt_acquire(nlp->lwp_thread);
                        lwkt_schedule(nlp->lwp_thread);
                } else {
                        spin_unlock(&bsd4_spin);
                }
        } else if (bsd4_runqcount) {
                if ((nlp = bsd4_chooseproc_locked(dd->uschedcp)) != NULL) {
                        KTR_COND_LOG(usched_sched_thread_process,
                            nlp->lwp_proc->p_pid == usched_bsd4_pid_debug,
                            gd->gd_cpuid,
                            nlp->lwp_proc->p_pid,
                            nlp->lwp_thread->td_gd->gd_cpuid);

                        dd->upri = nlp->lwp_priority;
                        dd->uschedcp = nlp;
                        dd->rrcount = 0;        /* reset round robin */
                        spin_unlock(&bsd4_spin);
                        lwkt_acquire(nlp->lwp_thread);
                        lwkt_schedule(nlp->lwp_thread);
                } else {
                        /*
                         * CHAINING CONDITION TRAIN
                         *
                         * We could not deal with the scheduler wakeup
                         * request on this cpu, locate a ready scheduler
                         * with no current lp assignment and chain to it.
                         *
                         * This ensures that a wakeup race which fails due
                         * to priority test does not leave other unscheduled
                         * cpus idle when the runqueue is not empty.
                         */
                        tmpmask = bsd4_rdyprocmask;
                        CPUMASK_NANDMASK(tmpmask, bsd4_curprocmask);
                        CPUMASK_ANDMASK(tmpmask, smp_active_mask);
                        if (CPUMASK_TESTNZERO(tmpmask)) {
                                tmpid = BSFCPUMASK(tmpmask);
                                tmpdd = &bsd4_pcpu[tmpid];
                                ATOMIC_CPUMASK_NANDBIT(bsd4_rdyprocmask, tmpid);
                                spin_unlock(&bsd4_spin);
                                wakeup(tmpdd->helper_thread);
                        } else {
                                spin_unlock(&bsd4_spin);
                        }

                        KTR_LOG(usched_sched_thread_no_process_found,
                                gd->gd_cpuid, (unsigned long)CPUMASK_LOWMASK(tmpmask));
                }
        } else {
                /*
                 * The runq is empty.
                 */
                spin_unlock(&bsd4_spin);
        }

        /*
         * We're descheduled unless someone scheduled us.  Switch away.
         * Exiting the critical section will cause splz() to be called
         * for us if interrupts and such are pending.
         */
        crit_exit_gd(gd);
        tsleep(dd->helper_thread, PINTERLOCKED, "schslp", 0);
    }
}

/* sysctl stick_to_level parameter */
static int
sysctl_usched_bsd4_stick_to_level(SYSCTL_HANDLER_ARGS)
{
        int error, new_val;

        new_val = usched_bsd4_stick_to_level;

        error = sysctl_handle_int(oidp, &new_val, 0, req);
        if (error != 0 || req->newptr == NULL)
                return (error);
        if (new_val > cpu_topology_levels_number - 1 || new_val < 0)
                return (EINVAL);
        usched_bsd4_stick_to_level = new_val;
        return (0);
}

/*
 * Setup our scheduler helpers.  Note that curprocmask bit 0 has already
 * been cleared by rqinit() and we should not mess with it further.
 */
static void
sched_thread_cpu_init(void)
{
        int i;
        int smt_not_supported = 0;
        int cache_coherent_not_supported = 0;

        if (bootverbose)
                kprintf("Start usched_bsd4 helpers on cpus:\n");

        sysctl_ctx_init(&usched_bsd4_sysctl_ctx);
        usched_bsd4_sysctl_tree =
                SYSCTL_ADD_NODE(&usched_bsd4_sysctl_ctx,
                                SYSCTL_STATIC_CHILDREN(_kern), OID_AUTO,
                                "usched_bsd4", CTLFLAG_RD, 0, "");

        for (i = 0; i < ncpus; ++i) {
                bsd4_pcpu_t dd = &bsd4_pcpu[i];
                cpumask_t mask;

                CPUMASK_ASSBIT(mask, i);

                if (CPUMASK_TESTMASK(mask, smp_active_mask) == 0)
                    continue;

                dd->cpunode = get_cpu_node_by_cpuid(i);

                if (dd->cpunode == NULL) {
                        smt_not_supported = 1;
                        cache_coherent_not_supported = 1;
                        if (bootverbose)
                                kprintf ("    cpu%d - WARNING: No CPU NODE "
                                         "found for cpu\n", i);
                } else {
                        switch (dd->cpunode->type) {
                        case THREAD_LEVEL:
                                if (bootverbose)
                                        kprintf ("    cpu%d - HyperThreading "
                                                 "available. Core siblings: ",
                                                 i);
                                break;
                        case CORE_LEVEL:
                                smt_not_supported = 1;

                                if (bootverbose)
                                        kprintf ("    cpu%d - No HT available, "
                                                 "multi-core/physical "
                                                 "cpu. Physical siblings: ",
                                                 i);
                                break;
                        case CHIP_LEVEL:
                                smt_not_supported = 1;

                                if (bootverbose)
                                        kprintf ("    cpu%d - No HT available, "
                                                 "single-core/physical cpu. "
                                                 "Package Siblings: ",
                                                 i);
                                break;
                        default:
                                /* Let's go for safe defaults here */
                                smt_not_supported = 1;
                                cache_coherent_not_supported = 1;
                                if (bootverbose)
                                        kprintf ("    cpu%d - Unknown cpunode->"
                                                 "type=%u. Siblings: ",
                                                 i,
                                                 (u_int)dd->cpunode->type);
                                break;
                        }

                        if (bootverbose) {
                                if (dd->cpunode->parent_node != NULL) {
                                        kprint_cpuset(&dd->cpunode->
                                                      parent_node->members);
                                        kprintf("\n");
                                } else {
                                        kprintf(" no siblings\n");
                                }
                        }
                }

                lwkt_create(sched_thread, NULL, &dd->helper_thread, NULL,
                            0, i, "usched %d", i);

                /*
                 * Allow user scheduling on the target cpu.  cpu #0 has already
                 * been enabled in rqinit().
                 */
                if (i)
                        ATOMIC_CPUMASK_NANDMASK(bsd4_curprocmask, mask);
                ATOMIC_CPUMASK_ORMASK(bsd4_rdyprocmask, mask);
                dd->upri = PRIBASE_NULL;

        }

        /* usched_bsd4 sysctl configurable parameters */

        SYSCTL_ADD_INT(&usched_bsd4_sysctl_ctx,
                       SYSCTL_CHILDREN(usched_bsd4_sysctl_tree),
                       OID_AUTO, "rrinterval", CTLFLAG_RW,
                       &usched_bsd4_rrinterval, 0, "");
        SYSCTL_ADD_INT(&usched_bsd4_sysctl_ctx,
                       SYSCTL_CHILDREN(usched_bsd4_sysctl_tree),
                       OID_AUTO, "decay", CTLFLAG_RW,
                       &usched_bsd4_decay, 0, "Extra decay when not running");
        SYSCTL_ADD_INT(&usched_bsd4_sysctl_ctx,
                       SYSCTL_CHILDREN(usched_bsd4_sysctl_tree),
                       OID_AUTO, "batch_time", CTLFLAG_RW,
                       &usched_bsd4_batch_time, 0, "Min batch counter value");
        SYSCTL_ADD_LONG(&usched_bsd4_sysctl_ctx,
                       SYSCTL_CHILDREN(usched_bsd4_sysctl_tree),
                       OID_AUTO, "kicks", CTLFLAG_RW,
                       &usched_bsd4_kicks, "Number of kickstarts");

        /* Add enable/disable option for SMT scheduling if supported */
        if (smt_not_supported) {
                usched_bsd4_smt = 0;
                SYSCTL_ADD_STRING(&usched_bsd4_sysctl_ctx,
                                  SYSCTL_CHILDREN(usched_bsd4_sysctl_tree),
                                  OID_AUTO, "smt", CTLFLAG_RD,
                                  "NOT SUPPORTED", 0, "SMT NOT SUPPORTED");
        } else {
                usched_bsd4_smt = 1;
                SYSCTL_ADD_INT(&usched_bsd4_sysctl_ctx,
                               SYSCTL_CHILDREN(usched_bsd4_sysctl_tree),
                               OID_AUTO, "smt", CTLFLAG_RW,
                               &usched_bsd4_smt, 0, "Enable SMT scheduling");
        }

        /*
         * Add enable/disable option for cache coherent scheduling
         * if supported
         */
        if (cache_coherent_not_supported) {
                usched_bsd4_cache_coherent = 0;
                SYSCTL_ADD_STRING(&usched_bsd4_sysctl_ctx,
                                  SYSCTL_CHILDREN(usched_bsd4_sysctl_tree),
                                  OID_AUTO, "cache_coherent", CTLFLAG_RD,
                                  "NOT SUPPORTED", 0,
                                  "Cache coherence NOT SUPPORTED");
        } else {
                usched_bsd4_cache_coherent = 1;
                SYSCTL_ADD_INT(&usched_bsd4_sysctl_ctx,
                               SYSCTL_CHILDREN(usched_bsd4_sysctl_tree),
                               OID_AUTO, "cache_coherent", CTLFLAG_RW,
                               &usched_bsd4_cache_coherent, 0,
                               "Enable/Disable cache coherent scheduling");

                SYSCTL_ADD_INT(&usched_bsd4_sysctl_ctx,
                               SYSCTL_CHILDREN(usched_bsd4_sysctl_tree),
                               OID_AUTO, "upri_affinity", CTLFLAG_RW,
                               &usched_bsd4_upri_affinity, 1,
                               "Number of PPQs in user priority check");

                SYSCTL_ADD_INT(&usched_bsd4_sysctl_ctx,
                               SYSCTL_CHILDREN(usched_bsd4_sysctl_tree),
                               OID_AUTO, "queue_checks", CTLFLAG_RW,
                               &usched_bsd4_queue_checks, 5,
                               "LWPs to check from a queue before giving up");

                SYSCTL_ADD_PROC(&usched_bsd4_sysctl_ctx,
                                SYSCTL_CHILDREN(usched_bsd4_sysctl_tree),
                                OID_AUTO, "stick_to_level",
                                CTLTYPE_INT | CTLFLAG_RW,
                                NULL, sizeof usched_bsd4_stick_to_level,
                                sysctl_usched_bsd4_stick_to_level, "I",
                                "Stick a process to this level. See sysctl"
                                "paremter hw.cpu_topology.level_description");
        }
}
SYSINIT(uschedtd, SI_BOOT2_USCHED, SI_ORDER_SECOND,
        sched_thread_cpu_init, NULL);