kernel - Add usched_dfly algorith, set as default for now (6)

[dragonfly.git] / sys / kern / usched_dfly.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.
 * 3. Neither the name of The DragonFly Project nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific, prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
 * COPYRIGHT HOLDERS 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/mplock2.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.
 */

int dfly_rebalanced;

#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.dfly.priority
#define lwp_forked      lwp_usdata.dfly.forked
#define lwp_rqindex     lwp_usdata.dfly.rqindex
#define lwp_estcpu      lwp_usdata.dfly.estcpu
#define lwp_batch       lwp_usdata.dfly.batch
#define lwp_rqtype      lwp_usdata.dfly.rqtype
#define lwp_qcpu        lwp_usdata.dfly.qcpu

struct usched_dfly_pcpu {
        struct spinlock spin;
        struct thread   helper_thread;
        short           rrcount;
        short           upri;
        int             uload;
        struct lwp      *uschedcp;
        struct rq       queues[NQS];
        struct rq       rtqueues[NQS];
        struct rq       idqueues[NQS];
        u_int32_t       queuebits;
        u_int32_t       rtqueuebits;
        u_int32_t       idqueuebits;
        int             runqcount;
        int             cpuid;
        cpumask_t       cpumask;
#ifdef SMP
        cpu_node_t      *cpunode;
#endif
};

typedef struct usched_dfly_pcpu *dfly_pcpu_t;

static void dfly_acquire_curproc(struct lwp *lp);
static void dfly_release_curproc(struct lwp *lp);
static void dfly_select_curproc(globaldata_t gd);
static void dfly_setrunqueue(struct lwp *lp);
static void dfly_setrunqueue_dd(dfly_pcpu_t rdd, struct lwp *lp);
static void dfly_schedulerclock(struct lwp *lp, sysclock_t period,
                                sysclock_t cpstamp);
static void dfly_recalculate_estcpu(struct lwp *lp);
static void dfly_resetpriority(struct lwp *lp);
static void dfly_forking(struct lwp *plp, struct lwp *lp);
static void dfly_exiting(struct lwp *lp, struct proc *);
static void dfly_uload_update(struct lwp *lp);
static void dfly_yield(struct lwp *lp);
#ifdef SMP
static dfly_pcpu_t dfly_choose_best_queue(struct lwp *lp);
static dfly_pcpu_t dfly_choose_worst_queue(dfly_pcpu_t dd);
static dfly_pcpu_t dfly_choose_queue_simple(dfly_pcpu_t dd, struct lwp *lp);
#if 0
static void dfly_wakeup_random_helper(dfly_pcpu_t notdd);
#endif
#endif

#ifdef SMP
static void dfly_need_user_resched_remote(void *dummy);
#endif
static struct lwp *dfly_chooseproc_locked(dfly_pcpu_t dd, struct lwp *chklp,
                                        int isremote);
static void dfly_remrunqueue_locked(dfly_pcpu_t dd, struct lwp *lp);
static void dfly_setrunqueue_locked(dfly_pcpu_t dd, struct lwp *lp);

struct usched usched_dfly = {
        { NULL },
        "dfly", "Original DragonFly Scheduler",
        NULL,                   /* default registration */
        NULL,                   /* default deregistration */
        dfly_acquire_curproc,
        dfly_release_curproc,
        dfly_setrunqueue,
        dfly_schedulerclock,
        dfly_recalculate_estcpu,
        dfly_resetpriority,
        dfly_forking,
        dfly_exiting,
        dfly_uload_update,
        NULL,                   /* setcpumask not supported */
        dfly_yield
};

/*
 * 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 cpumask_t dfly_curprocmask = -1; /* currently running a user process */
static cpumask_t dfly_rdyprocmask;      /* ready to accept a user process */
#ifdef SMP
static volatile int dfly_scancpu;
#endif
static struct usched_dfly_pcpu dfly_pcpu[MAXCPU];
static struct sysctl_ctx_list usched_dfly_sysctl_ctx;
static struct sysctl_oid *usched_dfly_sysctl_tree;

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

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

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

static int usched_dfly_chooser = 0;
SYSCTL_INT(_debug, OID_AUTO, dfly_chooser, CTLFLAG_RW,
           &usched_dfly_chooser, 0,
           "Print KTR debug information for this pid");

/* Tunning usched_dfly - configurable through kern.usched_dfly.* */
#ifdef SMP
static int usched_dfly_smt = 0;
static int usched_dfly_cache_coherent = 0;
static int usched_dfly_weight1 = 25;    /* thread's current cpu */
static int usched_dfly_weight2 = 0;     /* synchronous peer's current cpu */
                                        /* XXX can cause cpu flapping */
static int usched_dfly_weight3 = 10;    /* number of threads on queue */
static int usched_dfly_pull_enable = 1; /* allow pulls */
#endif
static int usched_dfly_rrinterval = (ESTCPUFREQ + 9) / 10;
static int usched_dfly_decay = 8;
static int usched_dfly_batch_time = 10;

/* KTR debug printings */

KTR_INFO_MASTER(usched);

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

#if 0
KTR_INFO(KTR_USCHED_DFLY, usched, dfly_acquire_curproc_urw, 0,
    "USCHED_DFLY(dfly_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_DFLY, usched, dfly_acquire_curproc_before_loop, 0,
    "USCHED_DFLY(dfly_acquire_curproc before loop: pid %d, cpuid %d, "
    "curr_cpuid %d)",
    pid_t pid, int cpuid, int curr);
KTR_INFO(KTR_USCHED_DFLY, usched, dfly_acquire_curproc_not, 0,
    "USCHED_DFLY(dfly_acquire_curproc couldn't acquire after "
    "dfly_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_DFLY, usched, dfly_acquire_curproc_switch, 0,
    "USCHED_DFLY(dfly_acquire_curproc after lwkt_switch: pid %d, "
    "cpuid %d, curr_cpuid %d)",
    pid_t pid, int cpuid, int curr);

KTR_INFO(KTR_USCHED_DFLY, usched, dfly_release_curproc, 0,
    "USCHED_DFLY(dfly_release_curproc before select: pid %d, "
    "cpuid %d, curr_cpuid %d)",
    pid_t pid, int cpuid, int curr);

KTR_INFO(KTR_USCHED_DFLY, usched, dfly_select_curproc, 0,
    "USCHED_DFLY(dfly_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);

#ifdef SMP
KTR_INFO(KTR_USCHED_DFLY, usched, batchy_test_false, 0,
    "USCHED_DFLY(batchy_looser_pri_test false: pid %d, "
    "cpuid %d, verify_mask %lu)",
    pid_t pid, int cpuid, cpumask_t mask);
KTR_INFO(KTR_USCHED_DFLY, usched, batchy_test_true, 0,
    "USCHED_DFLY(batchy_looser_pri_test true: pid %d, "
    "cpuid %d, verify_mask %lu)",
    pid_t pid, int cpuid, cpumask_t mask);

KTR_INFO(KTR_USCHED_DFLY, usched, dfly_setrunqueue_fc_smt, 0,
    "USCHED_DFLY(dfly_setrunqueue free cpus smt: pid %d, cpuid %d, "
    "mask %lu, curr_cpuid %d)",
    pid_t pid, int cpuid, cpumask_t mask, int curr);
KTR_INFO(KTR_USCHED_DFLY, usched, dfly_setrunqueue_fc_non_smt, 0,
    "USCHED_DFLY(dfly_setrunqueue free cpus check non_smt: pid %d, "
    "cpuid %d, mask %lu, curr_cpuid %d)",
    pid_t pid, int cpuid, cpumask_t mask, int curr);
KTR_INFO(KTR_USCHED_DFLY, usched, dfly_setrunqueue_rc, 0,
    "USCHED_DFLY(dfly_setrunqueue running cpus check: pid %d, "
    "cpuid %d, mask %lu, curr_cpuid %d)",
    pid_t pid, int cpuid, cpumask_t mask, int curr);
KTR_INFO(KTR_USCHED_DFLY, usched, dfly_setrunqueue_found, 0,
    "USCHED_DFLY(dfly_setrunqueue found cpu: pid %d, cpuid %d, "
    "mask %lu, found_cpuid %d, curr_cpuid %d)",
    pid_t pid, int cpuid, cpumask_t mask, int found_cpuid, int curr);
KTR_INFO(KTR_USCHED_DFLY, usched, dfly_setrunqueue_not_found, 0,
    "USCHED_DFLY(dfly_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_DFLY, usched, dfly_setrunqueue_found_best_cpuid, 0,
    "USCHED_DFLY(dfly_setrunqueue found cpu: pid %d, cpuid %d, "
    "mask %lu, found_cpuid %d, curr_cpuid %d)",
    pid_t pid, int cpuid, cpumask_t mask, int found_cpuid, int curr);
#endif
#endif

KTR_INFO(KTR_USCHED_DFLY, usched, chooseproc, 0,
    "USCHED_DFLY(chooseproc: pid %d, old_cpuid %d, curr_cpuid %d)",
    pid_t pid, int old_cpuid, int curr);
#ifdef SMP
#if 0
KTR_INFO(KTR_USCHED_DFLY, usched, chooseproc_cc, 0,
    "USCHED_DFLY(chooseproc_cc: pid %d, old_cpuid %d, curr_cpuid %d)",
    pid_t pid, int old_cpuid, int curr);
KTR_INFO(KTR_USCHED_DFLY, usched, chooseproc_cc_not_good, 0,
    "USCHED_DFLY(chooseproc_cc not good: pid %d, old_cpumask %lu, "
    "sibling_mask %lu, curr_cpumask %lu)",
    pid_t pid, cpumask_t old_cpumask, cpumask_t sibling_mask, cpumask_t curr);
KTR_INFO(KTR_USCHED_DFLY, usched, chooseproc_cc_elected, 0,
    "USCHED_DFLY(chooseproc_cc elected: pid %d, old_cpumask %lu, "
    "sibling_mask %lu, curr_cpumask: %lu)",
    pid_t pid, cpumask_t old_cpumask, cpumask_t sibling_mask, cpumask_t curr);
#endif

KTR_INFO(KTR_USCHED_DFLY, usched, sched_thread_no_process, 0,
    "USCHED_DFLY(sched_thread %d no process scheduled: pid %d, old_cpuid %d)",
    int id, pid_t pid, int cpuid);
KTR_INFO(KTR_USCHED_DFLY, usched, sched_thread_process, 0,
    "USCHED_DFLY(sched_thread %d process scheduled: pid %d, old_cpuid %d)",
    int id, pid_t pid, int cpuid);
#if 0
KTR_INFO(KTR_USCHED_DFLY, usched, sched_thread_no_process_found, 0,
    "USCHED_DFLY(sched_thread %d no process found; tmpmask %lu)",
    int id, cpumask_t tmpmask);
#endif
#endif

/*
 * DFLY_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 has already depressed our LWKT priority so we must not switch
 * until we have either assigned or disposed of the thread.
 *
 * 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.
 */
static void
dfly_acquire_curproc(struct lwp *lp)
{
        globaldata_t gd;
        dfly_pcpu_t dd;
        dfly_pcpu_t rdd;
        thread_t td;

        /*
         * 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);
        dfly_recalculate_estcpu(lp);

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

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

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

                /*
                 * 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 ((rdd = dfly_choose_best_queue(lp)) != dd) {
                        lwkt_deschedule(lp->lwp_thread);
                        dfly_setrunqueue_dd(rdd, lp);
                        lwkt_switch();
                        gd = mycpu;
                        dd = &dfly_pcpu[gd->gd_cpuid];
                } else if (dd->uschedcp == NULL) {
                        /*
                         * We can trivially become the current lwp.
                         */
                        atomic_set_cpumask(&dfly_curprocmask, gd->gd_cpumask);
                        dd->uschedcp = lp;
                        dd->upri = lp->lwp_priority;
                        KKASSERT(lp->lwp_qcpu == dd->cpuid);
                } else if (dd->uschedcp && (dd->upri & ~PPQMASK) >
                                           (lp->lwp_priority & ~PPQMASK)) {
                        /*
                         * 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,
                         * possibly rescheduling elsewhere when it calls
                         * setrunqueue.
                         *
                         * It is important to do a masked test to avoid the
                         * edge case where two near-equal-priority threads
                         * are constantly interrupting each other.
                         */
                        dd->uschedcp = lp;
                        dd->upri = lp->lwp_priority;
                        KKASSERT(lp->lwp_qcpu == dd->cpuid);
                } else {
                        /*
                         * We cannot become the current lwp, place the lp
                         * on the run-queue of this or another cpu and
                         * deschedule ourselves.
                         *
                         * When we are reactivated we will have another
                         * chance.
                         *
                         * Reload after a switch or setrunqueue/switch possibly
                         * moved us to another cpu.
                         */
                        lwkt_deschedule(lp->lwp_thread);
                        dfly_setrunqueue_dd(dd, lp);
                        lwkt_switch();
                        gd = mycpu;
                        dd = &dfly_pcpu[gd->gd_cpuid];
                }
        } while (dd->uschedcp != lp);

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

/*
 * DFLY_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
 * dfly_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 dfly_setrunqueue().
 */
static void
dfly_release_curproc(struct lwp *lp)
{
        globaldata_t gd = mycpu;
        dfly_pcpu_t dd = &dfly_pcpu[gd->gd_cpuid];

        /*
         * Make sure td_wakefromcpu is defaulted.  This will be overwritten
         * by wakeup().
         */
        lp->lwp_thread->td_wakefromcpu = gd->gd_cpuid;

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

                dd->uschedcp = NULL;    /* don't let lp be selected */
                dd->upri = PRIBASE_NULL;
                atomic_clear_cpumask(&dfly_curprocmask, gd->gd_cpumask);
                spin_unlock(&dd->spin);
                dfly_select_curproc(gd);
        }
}

/*
 * DFLY_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 dfly_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.
 */
static
void
dfly_select_curproc(globaldata_t gd)
{
        dfly_pcpu_t dd = &dfly_pcpu[gd->gd_cpuid];
        struct lwp *nlp;
        int cpuid = gd->gd_cpuid;

        crit_enter_gd(gd);

        spin_lock(&dd->spin);
        nlp = dfly_chooseproc_locked(dd, dd->uschedcp, 1);

        if (nlp) {
                atomic_set_cpumask(&dfly_curprocmask, CPUMASK(cpuid));
                dd->upri = nlp->lwp_priority;
                dd->uschedcp = nlp;
                dd->rrcount = 0;                /* reset round robin */
                spin_unlock(&dd->spin);
#ifdef SMP
                lwkt_acquire(nlp->lwp_thread);
#endif
                lwkt_schedule(nlp->lwp_thread);
        } else {
                spin_unlock(&dd->spin);
        }
        crit_exit_gd(gd);
}

/*
 * 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.
 * It must not be possible for anyone else to explicitly schedule this thread.
 *
 * The thread may be the current thread as a special case.
 */
static void
dfly_setrunqueue(struct lwp *lp)
{
        dfly_pcpu_t rdd;

        /*
         * First validate the process LWKT state.
         */
        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: rdd does not necessarily represent the current cpu.
         *       Instead it represents the cpu the thread was last
         *       scheduled on.
         */
        rdd = &dfly_pcpu[lp->lwp_qcpu];

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

#ifndef SMP
        /*
         * If we are not SMP we do not have a scheduler helper to kick
         * and must directly activate the process if none are scheduled.
         *
         * This is really only an issue when bootstrapping init since
         * the caller in all other cases will be a user process, and
         * even if released (rdd->uschedcp == NULL), that process will
         * kickstart the scheduler when it returns to user mode from
         * the kernel.
         *
         * NOTE: On SMP we can't just set some other cpu's uschedcp.
         */
        if (rdd->uschedcp == NULL) {
                spin_lock(&rdd->spin);
                if (rdd->uschedcp == NULL) {
                        atomic_set_cpumask(&dfly_curprocmask, 1);
                        rdd->uschedcp = lp;
                        rdd->upri = lp->lwp_priority;
                        spin_unlock(&rdd->spin);
                        lwkt_schedule(lp->lwp_thread);
                        return;
                }
                spin_unlock(&rdd->spin);
        }
#endif

#ifdef SMP
        /*
         * Ok, we have to setrunqueue some target cpu and request a reschedule
         * if necessary.
         *
         * We have to choose the best target cpu.  It might not be the current
         * target even if the current cpu has no running user thread (for
         * example, because the current cpu might be a hyperthread and its
         * sibling has a thread assigned).
         *
         * If we just forked it is most optimal to run the child on the same
         * cpu just in case the parent decides to wait for it (thus getting
         * off that cpu).  As long as there is nothing else runnable on the
         * cpu, that is.  If we did this unconditionally a parent forking
         * multiple children before waiting (e.g. make -j N) leaves other
         * cpus idle that could be working.
         */
        if (lp->lwp_forked) {
                lp->lwp_forked = 0;
                if (dfly_pcpu[lp->lwp_qcpu].runqcount)
                        rdd = dfly_choose_best_queue(lp);
                else
                        rdd = &dfly_pcpu[lp->lwp_qcpu];
                /* dfly_wakeup_random_helper(rdd); */
        } else {
                rdd = dfly_choose_best_queue(lp);
                /* rdd = &dfly_pcpu[lp->lwp_qcpu]; */
        }
#endif
        dfly_setrunqueue_dd(rdd, lp);
}

static void
dfly_setrunqueue_dd(dfly_pcpu_t rdd, struct lwp *lp)
{
#ifdef SMP
        globaldata_t rgd;

        /*
         * We might be moving the lp to another cpu's run queue, and once
         * on the runqueue (even if it is our cpu's), another cpu can rip
         * it away from us.
         *
         * TDF_MIGRATING might already be set if this is part of a
         * remrunqueue+setrunqueue sequence.
         */
        if ((lp->lwp_thread->td_flags & TDF_MIGRATING) == 0)
                lwkt_giveaway(lp->lwp_thread);

        rgd = globaldata_find(rdd->cpuid);

        /*
         * We lose control of the lp the moment we release the spinlock
         * after having placed it on the queue.  i.e. another cpu could pick
         * it up, or it could exit, or its priority could be further
         * adjusted, or something like that.
         *
         * WARNING! rdd can point to a foreign cpu!
         */
        spin_lock(&rdd->spin);
        dfly_setrunqueue_locked(rdd, lp);

        if (rgd == mycpu) {
                if ((rdd->upri & ~PPQMASK) > (lp->lwp_priority & ~PPQMASK)) {
                        spin_unlock(&rdd->spin);
                        if (rdd->uschedcp == NULL) {
                                wakeup_mycpu(&rdd->helper_thread); /* XXX */
                                need_user_resched();
                        } else {
                                need_user_resched();
                        }
                } else {
                        spin_unlock(&rdd->spin);
                }
        } else {
                atomic_clear_cpumask(&dfly_rdyprocmask, rgd->gd_cpumask);
                if ((rdd->upri & ~PPQMASK) > (lp->lwp_priority & ~PPQMASK)) {
                        spin_unlock(&rdd->spin);
                        lwkt_send_ipiq(rgd, dfly_need_user_resched_remote,
                                       NULL);
                } else {
                        spin_unlock(&rdd->spin);
                        wakeup(&rdd->helper_thread);
                }
        }
#else
        /*
         * Request a reschedule if appropriate.
         */
        spin_lock(&rdd->spin);
        dfly_setrunqueue_locked(rdd, lp);
        spin_unlock(&rdd->spin);
        if ((rdd->upri & ~PPQMASK) > (lp->lwp_priority & ~PPQMASK)) {
                need_user_resched();
        }
#endif
}

#if 0

/*
 * This wakes up a random helper that might have no work on its cpu to do.
 * The idea is to improve fork/fork-exec/fork-wait/exec and similar
 * process-spawning sequences by first scheduling the forked process
 * on the same cpu as the parent, in case the parent is just going to
 * wait*().  But if the parent does not wait we want another cpu to pick
 * the forked process up ASAP.
 *
 * The ipi/helper-scheduling sequence typically takes a lot longer to run
 * than a return-from-procedure-call and the parent then entering a
 * wait*().  There's a race here that we want the parent to win ONLY if
 * it is going to wait*().
 *
 * If a process sticks around for long enough normal scheduling action
 * will move it to the right place.
 */
static
void
dfly_wakeup_random_helper(dfly_pcpu_t notdd)
{
        cpumask_t tmpmask;
        cpumask_t mask;
        int cpuid;

        mask = dfly_rdyprocmask & ~dfly_curprocmask & smp_active_mask &
               usched_global_cpumask & ~notdd->cpumask;
        ++dfly_scancpu;
        cpuid = (dfly_scancpu & 0xFFFF) % ncpus;

        if (mask) {
                tmpmask = ~(CPUMASK(cpuid) - 1);
                if (mask & tmpmask)
                        cpuid = BSFCPUMASK(mask & tmpmask);
                else
                        cpuid = BSFCPUMASK(mask);
                atomic_clear_cpumask(&dfly_rdyprocmask, CPUMASK(cpuid));
                wakeup(&dfly_pcpu[cpuid].helper_thread);
        }
}

#endif

/*
 * 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.
 */
static
void
dfly_schedulerclock(struct lwp *lp, sysclock_t period, sysclock_t cpstamp)
{
        globaldata_t gd = mycpu;
        dfly_pcpu_t dd = &dfly_pcpu[gd->gd_cpuid];

        /*
         * 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_dfly_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_wr == 0);

        dfly_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.
 */
static
void
dfly_recalculate_estcpu(struct lwp *lp)
{
        globaldata_t gd = mycpu;
        dfly_pcpu_t dd = &dfly_pcpu[gd->gd_cpuid];
        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;
                dfly_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 (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 runqcount.
                 *
                 * estcpu is scaled by ESTCPUMAX.
                 *
                 * 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) *
                         (dd->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_dfly_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 dfly_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_dfly_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_dfly_debug == lp->lwp_proc->p_pid)
                        kprintf(" finalestcpu %d\n", lp->lwp_estcpu);
                dfly_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.
 */
static void
dfly_resetpriority(struct lwp *lp)
{
        dfly_pcpu_t rdd;
        int newpriority;
        u_short newrqtype;
        int rcpu;
        int checkpri;
        int estcpu;

        crit_enter();

        /*
         * Lock the scheduler (lp) belongs to.  This can be on a different
         * cpu.  Handle races.  This loop breaks out with the appropriate
         * rdd locked.
         */
        for (;;) {
                rcpu = lp->lwp_qcpu;
                cpu_ccfence();
                rdd = &dfly_pcpu[rcpu];
                spin_lock(&rdd->spin);
                if (rcpu == lp->lwp_qcpu)
                        break;
                spin_unlock(&rdd->spin);
        }

        /*
         * Calculate the new priority and queue type
         */
        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.
         *
         * Since uload is ~PPQMASK masked, no modifications are necessary if
         * we end up in the same run queue.
         */
        if ((lp->lwp_priority ^ newpriority) & ~PPQMASK) {
                int delta_uload;

                /*
                 * uload can change, calculate the adjustment to reduce
                 * edge cases since choosers scan the cpu topology without
                 * locks.
                 */
                if (lp->lwp_mpflags & LWP_MP_ULOAD) {
                        delta_uload =
                                -((lp->lwp_priority & ~PPQMASK) & PRIMASK) +
                                ((newpriority & ~PPQMASK) & PRIMASK);
                        atomic_add_int(&dfly_pcpu[lp->lwp_qcpu].uload,
                                       delta_uload);
                }
                if (lp->lwp_mpflags & LWP_MP_ONRUNQ) {
                        dfly_remrunqueue_locked(rdd, lp);
                        lp->lwp_priority = newpriority;
                        lp->lwp_rqtype = newrqtype;
                        lp->lwp_rqindex = (newpriority & PRIMASK) / PPQ;
                        dfly_setrunqueue_locked(rdd, lp);
                        checkpri = 1;
                } else {
                        lp->lwp_priority = newpriority;
                        lp->lwp_rqtype = newrqtype;
                        lp->lwp_rqindex = (newpriority & PRIMASK) / PPQ;
                        checkpri = 0;
                }
        } else {
                /*
                 * In the same PPQ, uload cannot change.
                 */
                lp->lwp_priority = newpriority;
                checkpri = 1;
                rcpu = -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 (rcpu >= 0) {
                if ((dfly_rdyprocmask & CPUMASK(rcpu)) &&
                    (checkpri == 0 ||
                     (rdd->upri & ~PRIMASK) > (lp->lwp_priority & ~PRIMASK))) {
#ifdef SMP
                        if (rcpu == mycpu->gd_cpuid) {
                                spin_unlock(&rdd->spin);
                                need_user_resched();
                        } else {
                                atomic_clear_cpumask(&dfly_rdyprocmask,
                                                     CPUMASK(rcpu));
                                spin_unlock(&rdd->spin);
                                lwkt_send_ipiq(globaldata_find(rcpu),
                                               dfly_need_user_resched_remote,
                                               NULL);
                        }
#else
                        spin_unlock(&rdd->spin);
                        need_user_resched();
#endif
                } else {
                        spin_unlock(&rdd->spin);
                }
        } else {
                spin_unlock(&rdd->spin);
        }
        crit_exit();
}

static
void
dfly_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();
}

/*
 * 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"
 */
static void
dfly_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);
        lp->lwp_forked = 1;

        /*
         * 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
dfly_exiting(struct lwp *lp, struct proc *child_proc)
{
        dfly_pcpu_t dd = &dfly_pcpu[lp->lwp_qcpu];

        if (lp->lwp_mpflags & LWP_MP_ULOAD) {
                atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ULOAD);
                atomic_add_int(&dd->uload,
                               -((lp->lwp_priority & ~PPQMASK) & PRIMASK));
        }
}

/*
 * This function cannot block in any way
 */
static void
dfly_uload_update(struct lwp *lp)
{
        dfly_pcpu_t dd = &dfly_pcpu[lp->lwp_qcpu];

        if (lp->lwp_thread->td_flags & TDF_RUNQ) {
                if ((lp->lwp_mpflags & LWP_MP_ULOAD) == 0) {
                        atomic_set_int(&lp->lwp_mpflags, LWP_MP_ULOAD);
                        atomic_add_int(&dd->uload,
                                   ((lp->lwp_priority & ~PPQMASK) & PRIMASK));
                }
        } else {
                if (lp->lwp_mpflags & LWP_MP_ULOAD) {
                        atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ULOAD);
                        atomic_add_int(&dd->uload,
                                   -((lp->lwp_priority & ~PPQMASK) & PRIMASK));
                }
        }
}

/*
 * 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.
 *
 * Must be called with dd->spin locked.  The spinlock is left intact through
 * the entire routine.
 *
 * if chklp is NULL this function will dive other cpu's queues looking
 * for work if the current queue is empty.
 */
static
struct lwp *
dfly_chooseproc_locked(dfly_pcpu_t dd, struct lwp *chklp, int isremote)
{
#ifdef SMP
        dfly_pcpu_t xdd;
#endif
        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;

        rtqbits = dd->rtqueuebits;
        tsqbits = dd->queuebits;
        idqbits = dd->idqueuebits;

        if (rtqbits) {
                pri = bsfl(rtqbits);
                q = &dd->rtqueues[pri];
                which = &dd->rtqueuebits;
                which2 = &rtqbits;
        } else if (tsqbits) {
                pri = bsfl(tsqbits);
                q = &dd->queues[pri];
                which = &dd->queuebits;
                which2 = &tsqbits;
        } else if (idqbits) {
                pri = bsfl(idqbits);
                q = &dd->idqueues[pri];
                which = &dd->idqueuebits;
                which2 = &idqbits;
        } else
#ifdef SMP
        if (isremote || usched_dfly_pull_enable == 0) {
                /*
                 * Queue is empty, disallow remote->remote recursion and
                 * do not pull if threads are active.
                 */
                return (NULL);
        } else {
                /*
                 * Pull a runnable thread from a remote run queue.  We have
                 * to adjust qcpu and uload manually because the lp we return
                 * might be assigned directly to uschedcp (setrunqueue might
                 * not be called).
                 */
                xdd = dfly_choose_worst_queue(dd);
                if (xdd && xdd != dd && spin_trylock(&xdd->spin)) {
                        lp = dfly_chooseproc_locked(xdd, NULL, 1);
                        if (lp) {
                                if (lp->lwp_mpflags & LWP_MP_ULOAD) {
                                        atomic_add_int(&xdd->uload,
                                            -((lp->lwp_priority & ~PPQMASK) &
                                              PRIMASK));
                                }
                                lp->lwp_qcpu = dd->cpuid;
                                atomic_add_int(&dd->uload,
                                    ((lp->lwp_priority & ~PPQMASK) & PRIMASK));
                                atomic_set_int(&lp->lwp_mpflags, LWP_MP_ULOAD);
                        }
                        spin_unlock(&xdd->spin);
                } else {
                        lp = NULL;
                }
                return (lp);
        }
#else
        {
                return NULL;
        }
#endif
        lp = TAILQ_FIRST(q);
        KASSERT(lp, ("chooseproc: no lwp on busy queue"));

        /*
         * 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);
        }

        KTR_COND_LOG(usched_chooseproc,
            lp->lwp_proc->p_pid == usched_dfly_pid_debug,
            lp->lwp_proc->p_pid,
            lp->lwp_thread->td_gd->gd_cpuid,
            mycpu->gd_cpuid);

        TAILQ_REMOVE(q, lp, lwp_procq);
        --dd->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;
}

#ifdef SMP

/*
 * USED TO PUSH RUNNABLE LWPS TO THE LEAST LOADED CPU.
 *
 * Choose a cpu node to schedule lp on, hopefully nearby its current
 * node.  We give the current node a modest advantage for obvious reasons.
 *
 * We also give the node the thread was woken up FROM a slight advantage
 * in order to try to schedule paired threads which synchronize/block waiting
 * for each other fairly close to each other.  Similarly in a network setting
 * this feature will also attempt to place a user process near the kernel
 * protocol thread that is feeding it data.  THIS IS A CRITICAL PART of the
 * algorithm as it heuristically groups synchronizing processes for locality
 * of reference in multi-socket systems.
 *
 * The caller will normally dfly_setrunqueue() lp on the returned queue.
 *
 * When the topology is known choose a cpu whos group has, in aggregate,
 * has the lowest weighted load.
 */
static
dfly_pcpu_t
dfly_choose_best_queue(struct lwp *lp)
{
        cpumask_t mask;
        cpu_node_t *cpup;
        cpu_node_t *cpun;
        cpu_node_t *cpub;
        dfly_pcpu_t dd1 = &dfly_pcpu[lp->lwp_qcpu];
        dfly_pcpu_t dd2 = &dfly_pcpu[lp->lwp_thread->td_wakefromcpu];
        dfly_pcpu_t rdd;
        int cpuid;
        int n;
        int count;
        int load;
        int lowest_load;

        /*
         * When the topology is unknown choose a random cpu that is hopefully
         * idle.
         */
        if (dd1->cpunode == NULL)
                return (dfly_choose_queue_simple(dd1, lp));

        /*
         * When the topology is known choose a cpu whos group has, in
         * aggregate, has the lowest weighted load.
         */
        cpup = root_cpu_node;
        rdd = dd1;

        while (cpup) {
                /*
                 * Degenerate case super-root
                 */
                if (cpup->child_node && cpup->child_no == 1) {
                        cpup = cpup->child_node;
                        continue;
                }

                /*
                 * Terminal cpunode
                 */
                if (cpup->child_node == NULL) {
                        rdd = &dfly_pcpu[BSFCPUMASK(cpup->members)];
                        break;
                }

                cpub = NULL;
                lowest_load = 0x7FFFFFFF;

                for (n = 0; n < cpup->child_no; ++n) {
                        /*
                         * Accumulate load information for all cpus
                         * which are members of this node.
                         */
                        cpun = &cpup->child_node[n];
                        mask = cpun->members & usched_global_cpumask &
                               smp_active_mask & lp->lwp_cpumask;
                        if (mask == 0)
                                continue;

                        /*
                         * Compensate if the lp is already accounted for in
                         * the aggregate uload for this mask set.  We want
                         * to calculate the loads as if lp was not present.
                         */
                        if ((lp->lwp_mpflags & LWP_MP_ULOAD) &&
                            CPUMASK(lp->lwp_qcpu) & mask) {
                                load = -((lp->lwp_priority & ~PPQMASK) &
                                         PRIMASK);
                        } else {
                                load = 0;
                        }

                        count = 0;
                        while (mask) {
                                cpuid = BSFCPUMASK(mask);
                                load += dfly_pcpu[cpuid].uload;
                                load += dfly_pcpu[cpuid].runqcount *
                                        usched_dfly_weight3;
                                mask &= ~CPUMASK(cpuid);
                                ++count;
                        }
                        load /= count;

                        /*
                         * Give a slight advantage to the cpu groups (lp)
                         * belongs to, and a very slight advantage to the
                         * cpu groups our synchronous partner belongs to.
                         */
                        if (cpun->members & dd1->cpumask)
                                load -= usched_dfly_weight1;
                        else if (cpun->members & dd2->cpumask)
                                load -= usched_dfly_weight2;

                        /*
                         * Calculate the best load
                         */
                        if (cpub == NULL || lowest_load > load ||
                            (lowest_load == load &&
                             (cpun->members & dd1->cpumask))
                        ) {
                                lowest_load = load;
                                cpub = cpun;
                        }
                }
                cpup = cpub;
        }
        if (usched_dfly_chooser)
                kprintf("lp %02d->%02d %s\n",
                        lp->lwp_qcpu, rdd->cpuid, lp->lwp_proc->p_comm);
        return (rdd);
}

/*
 * USED TO PULL RUNNABLE LWPS FROM THE MOST LOADED CPU.
 *
 * Choose the worst queue close to dd's cpu node with a non-empty runq.
 *
 * This is used by the thread chooser when the current cpu's queues are
 * empty to steal a thread from another cpu's queue.  We want to offload
 * the most heavily-loaded queue.
 */
static
dfly_pcpu_t
dfly_choose_worst_queue(dfly_pcpu_t dd)
{
        cpumask_t mask;
        cpu_node_t *cpup;
        cpu_node_t *cpun;
        cpu_node_t *cpub;
        dfly_pcpu_t rdd;
        int cpuid;
        int n;
        int count;
        int load;
        int highest_load;

        /*
         * When the topology is unknown choose a random cpu that is hopefully
         * idle.
         */
        if (dd->cpunode == NULL) {
                return (NULL);
        }

        /*
         * When the topology is known choose a cpu whos group has, in
         * aggregate, has the lowest weighted load.
         */
        cpup = root_cpu_node;
        rdd = dd;
        while (cpup) {
                /*
                 * Degenerate case super-root
                 */
                if (cpup->child_node && cpup->child_no == 1) {
                        cpup = cpup->child_node;
                        continue;
                }

                /*
                 * Terminal cpunode
                 */
                if (cpup->child_node == NULL) {
                        rdd = &dfly_pcpu[BSFCPUMASK(cpup->members)];
                        break;
                }

                cpub = NULL;
                highest_load = 0;

                for (n = 0; n < cpup->child_no; ++n) {
                        /*
                         * Accumulate load information for all cpus
                         * which are members of this node.
                         */
                        cpun = &cpup->child_node[n];
                        mask = cpun->members & usched_global_cpumask &
                               smp_active_mask;
                        if (mask == 0)
                                continue;
                        count = 0;
                        load = 0;
                        while (mask) {
                                cpuid = BSFCPUMASK(mask);
                                load += dfly_pcpu[cpuid].uload;
                                load += dfly_pcpu[cpuid].runqcount *
                                        usched_dfly_weight3;
                                mask &= ~CPUMASK(cpuid);
                                ++count;
                        }
                        load /= count;

                        /*
                         * Give a slight advantage to nearby cpus.
                         */
                        if (cpun->members & dd->cpumask)
                                load += usched_dfly_weight1;

                        /*
                         * The best candidate is the one with the worst
                         * (highest) load.  Prefer candiates that are
                         * closer to our cpu.
                         */
                        if (cpub == NULL || highest_load < load ||
                             (highest_load == load &&
                              (cpun->members & dd->cpumask))
                        ) {
                                highest_load = load;
                                cpub = cpun;
                        }
                }
                cpup = cpub;
        }
        return (rdd);
}

static
dfly_pcpu_t
dfly_choose_queue_simple(dfly_pcpu_t dd, struct lwp *lp)
{
        dfly_pcpu_t rdd;
        cpumask_t tmpmask;
        cpumask_t mask;
        int cpuid;

        /*
         * Fallback to the original heuristic, select random cpu,
         * first checking cpus not currently running a user thread.
         */
        ++dfly_scancpu;
        cpuid = (dfly_scancpu & 0xFFFF) % ncpus;
        mask = ~dfly_curprocmask & dfly_rdyprocmask & lp->lwp_cpumask &
               smp_active_mask & usched_global_cpumask;

        while (mask) {
                tmpmask = ~(CPUMASK(cpuid) - 1);
                if (mask & tmpmask)
                        cpuid = BSFCPUMASK(mask & tmpmask);
                else
                        cpuid = BSFCPUMASK(mask);
                rdd = &dfly_pcpu[cpuid];

                if ((rdd->upri & ~PPQMASK) >= (lp->lwp_priority & ~PPQMASK))
                        goto found;
                mask &= ~CPUMASK(cpuid);
        }

        /*
         * Then cpus which might have a currently running lp
         */
        cpuid = (dfly_scancpu & 0xFFFF) % ncpus;
        mask = dfly_curprocmask & dfly_rdyprocmask &
               lp->lwp_cpumask & smp_active_mask & usched_global_cpumask;

        while (mask) {
                tmpmask = ~(CPUMASK(cpuid) - 1);
                if (mask & tmpmask)
                        cpuid = BSFCPUMASK(mask & tmpmask);
                else
                        cpuid = BSFCPUMASK(mask);
                rdd = &dfly_pcpu[cpuid];

                if ((rdd->upri & ~PPQMASK) > (lp->lwp_priority & ~PPQMASK))
                        goto found;
                mask &= ~CPUMASK(cpuid);
        }

        /*
         * If we cannot find a suitable cpu we reload from dfly_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 = (dfly_scancpu & 0xFFFF) % ncpus;
        if ((CPUMASK(cpuid) & usched_global_cpumask) == 0)
                cpuid = 0;
        rdd = &dfly_pcpu[cpuid];
found:
        return (rdd);
}

static
void
dfly_need_user_resched_remote(void *dummy)
{
        globaldata_t gd = mycpu;
        dfly_pcpu_t  dd = &dfly_pcpu[gd->gd_cpuid];

        need_user_resched();

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

#endif

/*
 * dfly_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.
 *
 * uload is NOT adjusted here.  It is only adjusted if the lwkt_thread goes
 * to sleep or the lwp is moved to a different runq.
 */
static void
dfly_remrunqueue_locked(dfly_pcpu_t rdd, 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);
        --rdd->runqcount;
        /*rdd->uload -= (lp->lwp_priority & ~PPQMASK) & PRIMASK;*/
        KKASSERT(rdd->runqcount >= 0);

        pri = lp->lwp_rqindex;
        switch(lp->lwp_rqtype) {
        case RTP_PRIO_NORMAL:
                q = &rdd->queues[pri];
                which = &rdd->queuebits;
                break;
        case RTP_PRIO_REALTIME:
        case RTP_PRIO_FIFO:
                q = &rdd->rtqueues[pri];
                which = &rdd->rtqueuebits;
                break;
        case RTP_PRIO_IDLE:
                q = &rdd->idqueues[pri];
                which = &rdd->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);
        }
}

/*
 * dfly_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.
 *
 * NOTE ON ULOAD: This variable specifies the aggregate load on a cpu, the
 *                sum of the rough lwp_priority for all running and runnable
 *                processes.  Lower priority processes (higher lwp_priority
 *                values) actually DO count as more load, not less, because
 *                these are the programs which require the most care with
 *                regards to cpu selection.
 */
static void
dfly_setrunqueue_locked(dfly_pcpu_t rdd, struct lwp *lp)
{
        struct rq *q;
        u_int32_t *which;
        int pri;

        if (lp->lwp_qcpu != rdd->cpuid) {
                if (lp->lwp_mpflags & LWP_MP_ULOAD) {
                        atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ULOAD);
                        atomic_add_int(&dfly_pcpu[lp->lwp_qcpu].uload,
                                   -((lp->lwp_priority & ~PPQMASK) & PRIMASK));
                }
                lp->lwp_qcpu = rdd->cpuid;
        }

        KKASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0);
        atomic_set_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ);
        ++rdd->runqcount;
        if ((lp->lwp_mpflags & LWP_MP_ULOAD) == 0) {
                atomic_set_int(&lp->lwp_mpflags, LWP_MP_ULOAD);
                atomic_add_int(&dfly_pcpu[lp->lwp_qcpu].uload,
                               (lp->lwp_priority & ~PPQMASK) & PRIMASK);
        }

        pri = lp->lwp_rqindex;

        switch(lp->lwp_rqtype) {
        case RTP_PRIO_NORMAL:
                q = &rdd->queues[pri];
                which = &rdd->queuebits;
                break;
        case RTP_PRIO_REALTIME:
        case RTP_PRIO_FIFO:
                q = &rdd->rtqueues[pri];
                which = &rdd->rtqueuebits;
                break;
        case RTP_PRIO_IDLE:
                q = &rdd->idqueues[pri];
                which = &rdd->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;
}

#ifdef SMP

/*
 * 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.
 */
static void
dfly_helper_thread(void *dummy)
{
    globaldata_t gd;
    dfly_pcpu_t  dd;
    struct lwp *nlp;
    cpumask_t mask;
    int cpuid;

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

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

    tsleep(&dd->helper_thread, 0, "schslp", hz);

    for (;;) {
        /*
         * We use the LWKT deschedule-interlock trick to avoid racing
         * dfly_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(&dd->spin);

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

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

                        atomic_set_cpumask(&dfly_curprocmask, mask);
                        dd->upri = nlp->lwp_priority;
                        dd->uschedcp = nlp;
                        dd->rrcount = 0;        /* reset round robin */
                        spin_unlock(&dd->spin);
                        lwkt_acquire(nlp->lwp_thread);
                        lwkt_schedule(nlp->lwp_thread);
                } else {
                        spin_unlock(&dd->spin);
                }
        } else if (dd->runqcount) {
                /*
                 * Possibly find a better process to schedule.
                 */
                nlp = dfly_chooseproc_locked(dd, dd->uschedcp, 0);
                if (nlp) {
                        KTR_COND_LOG(usched_sched_thread_process,
                            nlp->lwp_proc->p_pid == usched_dfly_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(&dd->spin);
                        lwkt_acquire(nlp->lwp_thread);
                        lwkt_schedule(nlp->lwp_thread);
                } else {
                        /*
                         * Leave the thread on our run queue.  Another
                         * scheduler will try to pull it later.
                         */
                        spin_unlock(&dd->spin);
                }
        } else {
                /*
                 * The runq is empty.
                 */
                spin_unlock(&dd->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", hz);
    }
}

#if 0
static int
sysctl_usched_dfly_stick_to_level(SYSCTL_HANDLER_ARGS)
{
        int error, new_val;

        new_val = usched_dfly_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_dfly_stick_to_level = new_val;
        return (0);
}
#endif

/*
 * 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
dfly_helper_thread_cpu_init(void)
{
        int i;
        int j;
        int cpuid;
        int smt_not_supported = 0;
        int cache_coherent_not_supported = 0;

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

        sysctl_ctx_init(&usched_dfly_sysctl_ctx);
        usched_dfly_sysctl_tree =
                SYSCTL_ADD_NODE(&usched_dfly_sysctl_ctx,
                                SYSCTL_STATIC_CHILDREN(_kern), OID_AUTO,
                                "usched_dfly", CTLFLAG_RD, 0, "");

        for (i = 0; i < ncpus; ++i) {
                dfly_pcpu_t dd = &dfly_pcpu[i];
                cpumask_t mask = CPUMASK(i);

                if ((mask & smp_active_mask) == 0)
                    continue;

                spin_init(&dd->spin);
                dd->cpunode = get_cpu_node_by_cpuid(i);
                dd->cpuid = i;
                dd->cpumask = CPUMASK(i);
                for (j = 0; j < NQS; j++) {
                        TAILQ_INIT(&dd->queues[j]);
                        TAILQ_INIT(&dd->rtqueues[j]);
                        TAILQ_INIT(&dd->idqueues[j]);
                }
                atomic_clear_cpumask(&dfly_curprocmask, 1);

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

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

                                if (bootverbose)
                                        kprintf ("\tcpu%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 ("\tcpu%d - Unknown cpunode->"
                                                 "type=%u. Siblings: ",
                                                 i,
                                                 (u_int)dd->cpunode->type);
                                break;
                        }

                        if (bootverbose) {
                                if (dd->cpunode->parent_node != NULL) {
                                        CPUSET_FOREACH(cpuid, dd->cpunode->parent_node->members)
                                                kprintf("cpu%d ", cpuid);
                                        kprintf("\n");
                                } else {
                                        kprintf(" no siblings\n");
                                }
                        }
                }

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

                /*
                 * Allow user scheduling on the target cpu.  cpu #0 has already
                 * been enabled in rqinit().
                 */
                if (i)
                    atomic_clear_cpumask(&dfly_curprocmask, mask);
                atomic_set_cpumask(&dfly_rdyprocmask, mask);
                dd->upri = PRIBASE_NULL;

        }

        /* usched_dfly sysctl configurable parameters */

        SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx,
                       SYSCTL_CHILDREN(usched_dfly_sysctl_tree),
                       OID_AUTO, "rrinterval", CTLFLAG_RW,
                       &usched_dfly_rrinterval, 0, "");
        SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx,
                       SYSCTL_CHILDREN(usched_dfly_sysctl_tree),
                       OID_AUTO, "decay", CTLFLAG_RW,
                       &usched_dfly_decay, 0, "Extra decay when not running");
        SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx,
                       SYSCTL_CHILDREN(usched_dfly_sysctl_tree),
                       OID_AUTO, "batch_time", CTLFLAG_RW,
                       &usched_dfly_batch_time, 0, "Min batch counter value");

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

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

                SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx,
                               SYSCTL_CHILDREN(usched_dfly_sysctl_tree),
                               OID_AUTO, "weight1", CTLFLAG_RW,
                               &usched_dfly_weight1, 10,
                               "Weight selection for current cpu");

                SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx,
                               SYSCTL_CHILDREN(usched_dfly_sysctl_tree),
                               OID_AUTO, "weight2", CTLFLAG_RW,
                               &usched_dfly_weight2, 5,
                               "Weight selection for wakefrom cpu");

                SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx,
                               SYSCTL_CHILDREN(usched_dfly_sysctl_tree),
                               OID_AUTO, "weight3", CTLFLAG_RW,
                               &usched_dfly_weight3, 50,
                               "Weight selection for num threads on queue");

                SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx,
                               SYSCTL_CHILDREN(usched_dfly_sysctl_tree),
                               OID_AUTO, "pull_enable", CTLFLAG_RW,
                               &usched_dfly_pull_enable, 1,
                               "Allow pulls into empty queues");


#if 0
                SYSCTL_ADD_PROC(&usched_dfly_sysctl_ctx,
                                SYSCTL_CHILDREN(usched_dfly_sysctl_tree),
                                OID_AUTO, "stick_to_level",
                                CTLTYPE_INT | CTLFLAG_RW,
                                NULL, sizeof usched_dfly_stick_to_level,
                                sysctl_usched_dfly_stick_to_level, "I",
                                "Stick a process to this level. See sysctl"
                                "paremter hw.cpu_topology.level_description");
#endif
        }
}
SYSINIT(uschedtd, SI_BOOT2_USCHED, SI_ORDER_SECOND,
        dfly_helper_thread_cpu_init, NULL)

#else /* No SMP options - just add the configurable parameters to sysctl */

static void
sched_sysctl_tree_init(void)
{
        sysctl_ctx_init(&usched_dfly_sysctl_ctx);
        usched_dfly_sysctl_tree =
                SYSCTL_ADD_NODE(&usched_dfly_sysctl_ctx,
                                SYSCTL_STATIC_CHILDREN(_kern), OID_AUTO,
                                "usched_dfly", CTLFLAG_RD, 0, "");

        /* usched_dfly sysctl configurable parameters */
        SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx,
                       SYSCTL_CHILDREN(usched_dfly_sysctl_tree),
                       OID_AUTO, "rrinterval", CTLFLAG_RW,
                       &usched_dfly_rrinterval, 0, "");
        SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx,
                       SYSCTL_CHILDREN(usched_dfly_sysctl_tree),
                       OID_AUTO, "decay", CTLFLAG_RW,
                       &usched_dfly_decay, 0, "Extra decay when not running");
        SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx,
                       SYSCTL_CHILDREN(usched_dfly_sysctl_tree),
                       OID_AUTO, "batch_time", CTLFLAG_RW,
                       &usched_dfly_batch_time, 0, "Min batch counter value");
}
SYSINIT(uschedtd, SI_BOOT2_USCHED, SI_ORDER_SECOND,
        sched_sysctl_tree_init, NULL)
#endif