FreeBSD/Linux Kernel Cross Reference
sys/net/altq/altq_rmclass.c

     /*-
      * Copyright (c) 1991-1997 Regents of the University of California.
      * All rights reserved.
      *
      * 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. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the Network Research
     *      Group at Lawrence Berkeley Laboratory.
     * 4. Neither the name of the University nor of the Laboratory may be used
     *    to endorse or promote products derived from this software without
     *    specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
     *
     * LBL code modified by speer@eng.sun.com, May 1977.
     * For questions and/or comments, please send mail to cbq@ee.lbl.gov
     *
     * @(#)rm_class.c  1.48     97/12/05 SMI
     * $KAME: altq_rmclass.c,v 1.19 2005/04/13 03:44:25 suz Exp $
     * $FreeBSD$
     */
    #include "opt_altq.h"
    #include "opt_inet.h"
    #include "opt_inet6.h"
    #ifdef ALTQ_CBQ /* cbq is enabled by ALTQ_CBQ option in opt_altq.h */
    
    #include <sys/param.h>
    #include <sys/malloc.h>
    #include <sys/mbuf.h>
    #include <sys/socket.h>
    #include <sys/systm.h>
    #include <sys/errno.h>
    #include <sys/time.h>
    
    #include <net/if.h>
    #include <net/if_var.h>
    #include <net/if_private.h>
    
    #include <net/altq/if_altq.h>
    #include <net/altq/altq.h>
    #include <net/altq/altq_codel.h>
    #include <net/altq/altq_rmclass.h>
    #include <net/altq/altq_rmclass_debug.h>
    #include <net/altq/altq_red.h>
    #include <net/altq/altq_rio.h>
    
    /*
     * Local Macros
     */
    #define reset_cutoff(ifd)       { ifd->cutoff_ = RM_MAXDEPTH; }
    
    /*
     * Local routines.
     */
    
    static int      rmc_satisfied(struct rm_class *, struct timeval *);
    static void     rmc_wrr_set_weights(struct rm_ifdat *);
    static void     rmc_depth_compute(struct rm_class *);
    static void     rmc_depth_recompute(rm_class_t *);
    
    static mbuf_t   *_rmc_wrr_dequeue_next(struct rm_ifdat *, int);
    static mbuf_t   *_rmc_prr_dequeue_next(struct rm_ifdat *, int);
    
    static int      _rmc_addq(rm_class_t *, mbuf_t *);
    static void     _rmc_dropq(rm_class_t *);
    static mbuf_t   *_rmc_getq(rm_class_t *);
    static mbuf_t   *_rmc_pollq(rm_class_t *);
    
    static int      rmc_under_limit(struct rm_class *, struct timeval *);
    static void     rmc_tl_satisfied(struct rm_ifdat *, struct timeval *);
    static void     rmc_drop_action(struct rm_class *);
    static void     rmc_restart(void *);
    static void     rmc_root_overlimit(struct rm_class *, struct rm_class *);
    
    #define BORROW_OFFTIME
    /*
     * BORROW_OFFTIME (experimental):
     * borrow the offtime of the class borrowing from.
     * the reason is that when its own offtime is set, the class is unable
     * to borrow much, especially when cutoff is taking effect.
     * but when the borrowed class is overloaded (advidle is close to minidle),
    * use the borrowing class's offtime to avoid overload.
    */
   #define ADJUST_CUTOFF
   /*
    * ADJUST_CUTOFF (experimental):
    * if no underlimit class is found due to cutoff, increase cutoff and
    * retry the scheduling loop.
    * also, don't invoke delay_actions while cutoff is taking effect,
    * since a sleeping class won't have a chance to be scheduled in the
    * next loop.
    *
    * now heuristics for setting the top-level variable (cutoff_) becomes:
    *      1. if a packet arrives for a not-overlimit class, set cutoff
    *         to the depth of the class.
    *      2. if cutoff is i, and a packet arrives for an overlimit class
    *         with an underlimit ancestor at a lower level than i (say j),
    *         then set cutoff to j.
    *      3. at scheduling a packet, if there is no underlimit class
    *         due to the current cutoff level, increase cutoff by 1 and
    *         then try to schedule again.
    */
   
   /*
    * rm_class_t *
    * rmc_newclass(...) - Create a new resource management class at priority
    * 'pri' on the interface given by 'ifd'.
    *
    * nsecPerByte  is the data rate of the interface in nanoseconds/byte.
    *              E.g., 800 for a 10Mb/s ethernet.  If the class gets less
    *              than 100% of the bandwidth, this number should be the
    *              'effective' rate for the class.  Let f be the
    *              bandwidth fraction allocated to this class, and let
    *              nsPerByte be the data rate of the output link in
    *              nanoseconds/byte.  Then nsecPerByte is set to
    *              nsPerByte / f.  E.g., 1600 (= 800 / .5)
    *              for a class that gets 50% of an ethernet's bandwidth.
    *
    * action       the routine to call when the class is over limit.
    *
    * maxq         max allowable queue size for class (in packets).
    *
    * parent       parent class pointer.
    *
    * borrow       class to borrow from (should be either 'parent' or null).
    *
    * maxidle      max value allowed for class 'idle' time estimate (this
    *              parameter determines how large an initial burst of packets
    *              can be before overlimit action is invoked.
    *
    * offtime      how long 'delay' action will delay when class goes over
    *              limit (this parameter determines the steady-state burst
    *              size when a class is running over its limit).
    *
    * Maxidle and offtime have to be computed from the following:  If the
    * average packet size is s, the bandwidth fraction allocated to this
    * class is f, we want to allow b packet bursts, and the gain of the
    * averaging filter is g (= 1 - 2^(-RM_FILTER_GAIN)), then:
    *
    *   ptime = s * nsPerByte * (1 - f) / f
    *   maxidle = ptime * (1 - g^b) / g^b
    *   minidle = -ptime * (1 / (f - 1))
    *   offtime = ptime * (1 + 1/(1 - g) * (1 - g^(b - 1)) / g^(b - 1)
    *
    * Operationally, it's convenient to specify maxidle & offtime in units
    * independent of the link bandwidth so the maxidle & offtime passed to
    * this routine are the above values multiplied by 8*f/(1000*nsPerByte).
    * (The constant factor is a scale factor needed to make the parameters
    * integers.  This scaling also means that the 'unscaled' values of
    * maxidle*nsecPerByte/8 and offtime*nsecPerByte/8 will be in microseconds,
    * not nanoseconds.)  Also note that the 'idle' filter computation keeps
    * an estimate scaled upward by 2^RM_FILTER_GAIN so the passed value of
    * maxidle also must be scaled upward by this value.  Thus, the passed
    * values for maxidle and offtime can be computed as follows:
    *
    * maxidle = maxidle * 2^RM_FILTER_GAIN * 8 / (1000 * nsecPerByte)
    * offtime = offtime * 8 / (1000 * nsecPerByte)
    *
    * When USE_HRTIME is employed, then maxidle and offtime become:
    *      maxidle = maxilde * (8.0 / nsecPerByte);
    *      offtime = offtime * (8.0 / nsecPerByte);
    */
   struct rm_class *
   rmc_newclass(int pri, struct rm_ifdat *ifd, u_int nsecPerByte,
       void (*action)(rm_class_t *, rm_class_t *), int maxq,
       struct rm_class *parent, struct rm_class *borrow, u_int maxidle,
       int minidle, u_int offtime, int pktsize, int flags)
   {
           struct rm_class *cl;
           struct rm_class *peer;
           int              s;
   
           if (pri >= RM_MAXPRIO)
                   return (NULL);
   #ifndef ALTQ_RED
           if (flags & RMCF_RED) {
   #ifdef ALTQ_DEBUG
                   printf("rmc_newclass: RED not configured for CBQ!\n");
   #endif
                   return (NULL);
           }
   #endif
   #ifndef ALTQ_RIO
           if (flags & RMCF_RIO) {
   #ifdef ALTQ_DEBUG
                   printf("rmc_newclass: RIO not configured for CBQ!\n");
   #endif
                   return (NULL);
           }
   #endif
   #ifndef ALTQ_CODEL
           if (flags & RMCF_CODEL) {
   #ifdef ALTQ_DEBUG
                   printf("rmc_newclass: CODEL not configured for CBQ!\n");
   #endif
                   return (NULL);
           }
   #endif
   
           cl = malloc(sizeof(struct rm_class), M_DEVBUF, M_NOWAIT | M_ZERO);
           if (cl == NULL)
                   return (NULL);
           CALLOUT_INIT(&cl->callout_);
           cl->q_ = malloc(sizeof(class_queue_t), M_DEVBUF, M_NOWAIT | M_ZERO);
           if (cl->q_ == NULL) {
                   free(cl, M_DEVBUF);
                   return (NULL);
           }
   
           /*
            * Class initialization.
            */
           cl->children_ = NULL;
           cl->parent_ = parent;
           cl->borrow_ = borrow;
           cl->leaf_ = 1;
           cl->ifdat_ = ifd;
           cl->pri_ = pri;
           cl->allotment_ = RM_NS_PER_SEC / nsecPerByte; /* Bytes per sec */
           cl->depth_ = 0;
           cl->qthresh_ = 0;
           cl->ns_per_byte_ = nsecPerByte;
   
           qlimit(cl->q_) = maxq;
           qtype(cl->q_) = Q_DROPHEAD;
           qlen(cl->q_) = 0;
           cl->flags_ = flags;
   
   #if 1 /* minidle is also scaled in ALTQ */
           cl->minidle_ = (minidle * (int)nsecPerByte) / 8;
           if (cl->minidle_ > 0)
                   cl->minidle_ = 0;
   #else
           cl->minidle_ = minidle;
   #endif
           cl->maxidle_ = (maxidle * nsecPerByte) / 8;
           if (cl->maxidle_ == 0)
                   cl->maxidle_ = 1;
   #if 1 /* offtime is also scaled in ALTQ */
           cl->avgidle_ = cl->maxidle_;
           cl->offtime_ = ((offtime * nsecPerByte) / 8) >> RM_FILTER_GAIN;
           if (cl->offtime_ == 0)
                   cl->offtime_ = 1;
   #else
           cl->avgidle_ = 0;
           cl->offtime_ = (offtime * nsecPerByte) / 8;
   #endif
           cl->overlimit = action;
   
   #ifdef ALTQ_RED
           if (flags & (RMCF_RED|RMCF_RIO)) {
                   int red_flags, red_pkttime;
   
                   red_flags = 0;
                   if (flags & RMCF_ECN)
                           red_flags |= REDF_ECN;
                   if (flags & RMCF_FLOWVALVE)
                           red_flags |= REDF_FLOWVALVE;
   #ifdef ALTQ_RIO
                   if (flags & RMCF_CLEARDSCP)
                           red_flags |= RIOF_CLEARDSCP;
   #endif
                   red_pkttime = nsecPerByte * pktsize  / 1000;
   
                   if (flags & RMCF_RED) {
                           cl->red_ = red_alloc(0, 0,
                               qlimit(cl->q_) * 10/100,
                               qlimit(cl->q_) * 30/100,
                               red_flags, red_pkttime);
                           if (cl->red_ != NULL)
                                   qtype(cl->q_) = Q_RED;
                   }
   #ifdef ALTQ_RIO
                   else {
                           cl->red_ = (red_t *)rio_alloc(0, NULL,
                                                         red_flags, red_pkttime);
                           if (cl->red_ != NULL)
                                   qtype(cl->q_) = Q_RIO;
                   }
   #endif
           }
   #endif /* ALTQ_RED */
   #ifdef ALTQ_CODEL
           if (flags & RMCF_CODEL) {
                   cl->codel_ = codel_alloc(5, 100, 0);
                   if (cl->codel_ != NULL)
                           qtype(cl->q_) = Q_CODEL;
           }
   #endif
   
           /*
            * put the class into the class tree
            */
           s = splnet();
           IFQ_LOCK(ifd->ifq_);
           if ((peer = ifd->active_[pri]) != NULL) {
                   /* find the last class at this pri */
                   cl->peer_ = peer;
                   while (peer->peer_ != ifd->active_[pri])
                           peer = peer->peer_;
                   peer->peer_ = cl;
           } else {
                   ifd->active_[pri] = cl;
                   cl->peer_ = cl;
           }
   
           if (cl->parent_) {
                   cl->next_ = parent->children_;
                   parent->children_ = cl;
                   parent->leaf_ = 0;
           }
   
           /*
            * Compute the depth of this class and its ancestors in the class
            * hierarchy.
            */
           rmc_depth_compute(cl);
   
           /*
            * If CBQ's WRR is enabled, then initialize the class WRR state.
            */
           if (ifd->wrr_) {
                   ifd->num_[pri]++;
                   ifd->alloc_[pri] += cl->allotment_;
                   rmc_wrr_set_weights(ifd);
           }
           IFQ_UNLOCK(ifd->ifq_);
           splx(s);
           return (cl);
   }
   
   int
   rmc_modclass(struct rm_class *cl, u_int nsecPerByte, int maxq, u_int maxidle,
       int minidle, u_int offtime, int pktsize)
   {
           struct rm_ifdat *ifd;
           u_int            old_allotment;
           int              s;
   
           ifd = cl->ifdat_;
           old_allotment = cl->allotment_;
   
           s = splnet();
           IFQ_LOCK(ifd->ifq_);
           cl->allotment_ = RM_NS_PER_SEC / nsecPerByte; /* Bytes per sec */
           cl->qthresh_ = 0;
           cl->ns_per_byte_ = nsecPerByte;
   
           qlimit(cl->q_) = maxq;
   
   #if 1 /* minidle is also scaled in ALTQ */
           cl->minidle_ = (minidle * nsecPerByte) / 8;
           if (cl->minidle_ > 0)
                   cl->minidle_ = 0;
   #else
           cl->minidle_ = minidle;
   #endif
           cl->maxidle_ = (maxidle * nsecPerByte) / 8;
           if (cl->maxidle_ == 0)
                   cl->maxidle_ = 1;
   #if 1 /* offtime is also scaled in ALTQ */
           cl->avgidle_ = cl->maxidle_;
           cl->offtime_ = ((offtime * nsecPerByte) / 8) >> RM_FILTER_GAIN;
           if (cl->offtime_ == 0)
                   cl->offtime_ = 1;
   #else
           cl->avgidle_ = 0;
           cl->offtime_ = (offtime * nsecPerByte) / 8;
   #endif
   
           /*
            * If CBQ's WRR is enabled, then initialize the class WRR state.
            */
           if (ifd->wrr_) {
                   ifd->alloc_[cl->pri_] += cl->allotment_ - old_allotment;
                   rmc_wrr_set_weights(ifd);
           }
           IFQ_UNLOCK(ifd->ifq_);
           splx(s);
           return (0);
   }
   
   /*
    * static void
    * rmc_wrr_set_weights(struct rm_ifdat *ifdat) - This function computes
    *      the appropriate run robin weights for the CBQ weighted round robin
    *      algorithm.
    *
    *      Returns: NONE
    */
   
   static void
   rmc_wrr_set_weights(struct rm_ifdat *ifd)
   {
           int             i;
           struct rm_class *cl, *clh;
   
           for (i = 0; i < RM_MAXPRIO; i++) {
                   /*
                    * This is inverted from that of the simulator to
                    * maintain precision.
                    */
                   if (ifd->num_[i] == 0)
                           ifd->M_[i] = 0;
                   else
                           ifd->M_[i] = ifd->alloc_[i] /
                                   (ifd->num_[i] * ifd->maxpkt_);
                   /*
                    * Compute the weighted allotment for each class.
                    * This takes the expensive div instruction out
                    * of the main loop for the wrr scheduling path.
                    * These only get recomputed when a class comes or
                    * goes.
                    */
                   if (ifd->active_[i] != NULL) {
                           clh = cl = ifd->active_[i];
                           do {
                                   /* safe-guard for slow link or alloc_ == 0 */
                                   if (ifd->M_[i] == 0)
                                           cl->w_allotment_ = 0;
                                   else
                                           cl->w_allotment_ = cl->allotment_ /
                                                   ifd->M_[i];
                                   cl = cl->peer_;
                           } while ((cl != NULL) && (cl != clh));
                   }
           }
   }
   
   int
   rmc_get_weight(struct rm_ifdat *ifd, int pri)
   {
           if ((pri >= 0) && (pri < RM_MAXPRIO))
                   return (ifd->M_[pri]);
           else
                   return (0);
   }
   
   /*
    * static void
    * rmc_depth_compute(struct rm_class *cl) - This function computes the
    *      appropriate depth of class 'cl' and its ancestors.
    *
    *      Returns:        NONE
    */
   
   static void
   rmc_depth_compute(struct rm_class *cl)
   {
           rm_class_t      *t = cl, *p;
   
           /*
            * Recompute the depth for the branch of the tree.
            */
           while (t != NULL) {
                   p = t->parent_;
                   if (p && (t->depth_ >= p->depth_)) {
                           p->depth_ = t->depth_ + 1;
                           t = p;
                   } else
                           t = NULL;
           }
   }
   
   /*
    * static void
    * rmc_depth_recompute(struct rm_class *cl) - This function re-computes
    *      the depth of the tree after a class has been deleted.
    *
    *      Returns:        NONE
    */
   
   static void
   rmc_depth_recompute(rm_class_t *cl)
   {
   #if 1 /* ALTQ */
           rm_class_t      *p, *t;
   
           p = cl;
           while (p != NULL) {
                   if ((t = p->children_) == NULL) {
                           p->depth_ = 0;
                   } else {
                           int cdepth = 0;
   
                           while (t != NULL) {
                                   if (t->depth_ > cdepth)
                                           cdepth = t->depth_;
                                   t = t->next_;
                           }
   
                           if (p->depth_ == cdepth + 1)
                                   /* no change to this parent */
                                   return;
   
                           p->depth_ = cdepth + 1;
                   }
   
                   p = p->parent_;
           }
   #else
           rm_class_t      *t;
   
           if (cl->depth_ >= 1) {
                   if (cl->children_ == NULL) {
                           cl->depth_ = 0;
                   } else if ((t = cl->children_) != NULL) {
                           while (t != NULL) {
                                   if (t->children_ != NULL)
                                           rmc_depth_recompute(t);
                                   t = t->next_;
                           }
                   } else
                           rmc_depth_compute(cl);
           }
   #endif
   }
   
   /*
    * void
    * rmc_delete_class(struct rm_ifdat *ifdat, struct rm_class *cl) - This
    *      function deletes a class from the link-sharing structure and frees
    *      all resources associated with the class.
    *
    *      Returns: NONE
    */
   
   void
   rmc_delete_class(struct rm_ifdat *ifd, struct rm_class *cl)
   {
           struct rm_class *p, *head, *previous;
           int              s;
   
           ASSERT(cl->children_ == NULL);
   
           if (cl->sleeping_)
                   CALLOUT_STOP(&cl->callout_);
   
           s = splnet();
           IFQ_LOCK(ifd->ifq_);
           /*
            * Free packets in the packet queue.
            * XXX - this may not be a desired behavior.  Packets should be
            *              re-queued.
            */
           rmc_dropall(cl);
   
           /*
            * If the class has a parent, then remove the class from the
            * class from the parent's children chain.
            */
           if (cl->parent_ != NULL) {
                   head = cl->parent_->children_;
                   p = previous = head;
                   if (head->next_ == NULL) {
                           ASSERT(head == cl);
                           cl->parent_->children_ = NULL;
                           cl->parent_->leaf_ = 1;
                   } else while (p != NULL) {
                           if (p == cl) {
                                   if (cl == head)
                                           cl->parent_->children_ = cl->next_;
                                   else
                                           previous->next_ = cl->next_;
                                   cl->next_ = NULL;
                                   p = NULL;
                           } else {
                                   previous = p;
                                   p = p->next_;
                           }
                   }
           }
   
           /*
            * Delete class from class priority peer list.
            */
           if ((p = ifd->active_[cl->pri_]) != NULL) {
                   /*
                    * If there is more than one member of this priority
                    * level, then look for class(cl) in the priority level.
                    */
                   if (p != p->peer_) {
                           while (p->peer_ != cl)
                                   p = p->peer_;
                           p->peer_ = cl->peer_;
   
                           if (ifd->active_[cl->pri_] == cl)
                                   ifd->active_[cl->pri_] = cl->peer_;
                   } else {
                           ASSERT(p == cl);
                           ifd->active_[cl->pri_] = NULL;
                   }
           }
   
           /*
            * Recompute the WRR weights.
            */
           if (ifd->wrr_) {
                   ifd->alloc_[cl->pri_] -= cl->allotment_;
                   ifd->num_[cl->pri_]--;
                   rmc_wrr_set_weights(ifd);
           }
   
           /*
            * Re-compute the depth of the tree.
            */
   #if 1 /* ALTQ */
           rmc_depth_recompute(cl->parent_);
   #else
           rmc_depth_recompute(ifd->root_);
   #endif
   
           IFQ_UNLOCK(ifd->ifq_);
           splx(s);
   
           /*
            * Free the class structure.
            */
           if (cl->red_ != NULL) {
   #ifdef ALTQ_RIO
                   if (q_is_rio(cl->q_))
                           rio_destroy((rio_t *)cl->red_);
   #endif
   #ifdef ALTQ_RED
                   if (q_is_red(cl->q_))
                           red_destroy(cl->red_);
   #endif
   #ifdef ALTQ_CODEL
                   if (q_is_codel(cl->q_))
                           codel_destroy(cl->codel_);
   #endif
           }
           free(cl->q_, M_DEVBUF);
           free(cl, M_DEVBUF);
   }
   
   /*
    * void
    * rmc_init(...) - Initialize the resource management data structures
    *      associated with the output portion of interface 'ifp'.  'ifd' is
    *      where the structures will be built (for backwards compatibility, the
    *      structures aren't kept in the ifnet struct).  'nsecPerByte'
    *      gives the link speed (inverse of bandwidth) in nanoseconds/byte.
    *      'restart' is the driver-specific routine that the generic 'delay
    *      until under limit' action will call to restart output.  `maxq'
    *      is the queue size of the 'link' & 'default' classes.  'maxqueued'
    *      is the maximum number of packets that the resource management
    *      code will allow to be queued 'downstream' (this is typically 1).
    *
    *      Returns:        NONE
    */
   
   void
   rmc_init(struct ifaltq *ifq, struct rm_ifdat *ifd, u_int nsecPerByte,
       void (*restart)(struct ifaltq *), int maxq, int maxqueued, u_int maxidle,
       int minidle, u_int offtime, int flags)
   {
           int             i, mtu;
   
           /*
            * Initialize the CBQ tracing/debug facility.
            */
           CBQTRACEINIT();
   
           bzero((char *)ifd, sizeof (*ifd));
           mtu = ifq->altq_ifp->if_mtu;
           ifd->ifq_ = ifq;
           ifd->restart = restart;
           ifd->maxqueued_ = maxqueued;
           ifd->ns_per_byte_ = nsecPerByte;
           ifd->maxpkt_ = mtu;
           ifd->wrr_ = (flags & RMCF_WRR) ? 1 : 0;
           ifd->efficient_ = (flags & RMCF_EFFICIENT) ? 1 : 0;
   #if 1
           ifd->maxiftime_ = mtu * nsecPerByte / 1000 * 16;
           if (mtu * nsecPerByte > 10 * 1000000)
                   ifd->maxiftime_ /= 4;
   #endif
   
           reset_cutoff(ifd);
           CBQTRACE(rmc_init, 'INIT', ifd->cutoff_);
   
           /*
            * Initialize the CBQ's WRR state.
            */
           for (i = 0; i < RM_MAXPRIO; i++) {
                   ifd->alloc_[i] = 0;
                   ifd->M_[i] = 0;
                   ifd->num_[i] = 0;
                   ifd->na_[i] = 0;
                   ifd->active_[i] = NULL;
           }
   
           /*
            * Initialize current packet state.
            */
           ifd->qi_ = 0;
           ifd->qo_ = 0;
           for (i = 0; i < RM_MAXQUEUED; i++) {
                   ifd->class_[i] = NULL;
                   ifd->curlen_[i] = 0;
                   ifd->borrowed_[i] = NULL;
           }
   
           /*
            * Create the root class of the link-sharing structure.
            */
           if ((ifd->root_ = rmc_newclass(0, ifd,
                                          nsecPerByte,
                                          rmc_root_overlimit, maxq, 0, 0,
                                          maxidle, minidle, offtime,
                                          0, 0)) == NULL) {
                   printf("rmc_init: root class not allocated\n");
                   return ;
           }
           ifd->root_->depth_ = 0;
   }
   
   /*
    * void
    * rmc_queue_packet(struct rm_class *cl, mbuf_t *m) - Add packet given by
    *      mbuf 'm' to queue for resource class 'cl'.  This routine is called
    *      by a driver's if_output routine.  This routine must be called with
    *      output packet completion interrupts locked out (to avoid racing with
    *      rmc_dequeue_next).
    *
    *      Returns:        0 on successful queueing
    *                      -1 when packet drop occurs
    */
   int
   rmc_queue_packet(struct rm_class *cl, mbuf_t *m)
   {
           struct timeval   now;
           struct rm_ifdat *ifd = cl->ifdat_;
           int              cpri = cl->pri_;
           int              is_empty = qempty(cl->q_);
   
           RM_GETTIME(now);
           if (ifd->cutoff_ > 0) {
                   if (TV_LT(&cl->undertime_, &now)) {
                           if (ifd->cutoff_ > cl->depth_)
                                   ifd->cutoff_ = cl->depth_;
                           CBQTRACE(rmc_queue_packet, 'ffoc', cl->depth_);
                   }
   #if 1 /* ALTQ */
                   else {
                           /*
                            * the class is overlimit. if the class has
                            * underlimit ancestors, set cutoff to the lowest
                            * depth among them.
                            */
                           struct rm_class *borrow = cl->borrow_;
   
                           while (borrow != NULL &&
                                  borrow->depth_ < ifd->cutoff_) {
                                   if (TV_LT(&borrow->undertime_, &now)) {
                                           ifd->cutoff_ = borrow->depth_;
                                           CBQTRACE(rmc_queue_packet, 'ffob', ifd->cutoff_);
                                           break;
                                   }
                                   borrow = borrow->borrow_;
                           }
                   }
   #else /* !ALTQ */
                   else if ((ifd->cutoff_ > 1) && cl->borrow_) {
                           if (TV_LT(&cl->borrow_->undertime_, &now)) {
                                   ifd->cutoff_ = cl->borrow_->depth_;
                                   CBQTRACE(rmc_queue_packet, 'ffob',
                                            cl->borrow_->depth_);
                           }
                   }
   #endif /* !ALTQ */
           }
   
           if (_rmc_addq(cl, m) < 0)
                   /* failed */
                   return (-1);
   
           if (is_empty) {
                   CBQTRACE(rmc_queue_packet, 'ytpe', cl->stats_.handle);
                   ifd->na_[cpri]++;
           }
   
           if (qlen(cl->q_) > qlimit(cl->q_)) {
                   /* note: qlimit can be set to 0 or 1 */
                   rmc_drop_action(cl);
                   return (-1);
           }
           return (0);
   }
   
   /*
    * void
    * rmc_tl_satisfied(struct rm_ifdat *ifd, struct timeval *now) - Check all
    *      classes to see if there are satified.
    */
   
   static void
   rmc_tl_satisfied(struct rm_ifdat *ifd, struct timeval *now)
   {
           int              i;
           rm_class_t      *p, *bp;
   
           for (i = RM_MAXPRIO - 1; i >= 0; i--) {
                   if ((bp = ifd->active_[i]) != NULL) {
                           p = bp;
                           do {
                                   if (!rmc_satisfied(p, now)) {
                                           ifd->cutoff_ = p->depth_;
                                           return;
                                   }
                                   p = p->peer_;
                           } while (p != bp);
                   }
           }
   
           reset_cutoff(ifd);
   }
   
   /*
    * rmc_satisfied - Return 1 of the class is satisfied.  O, otherwise.
    */
   
   static int
   rmc_satisfied(struct rm_class *cl, struct timeval *now)
   {
           rm_class_t      *p;
   
           if (cl == NULL)
                   return (1);
           if (TV_LT(now, &cl->undertime_))
                   return (1);
           if (cl->depth_ == 0) {
                   if (!cl->sleeping_ && (qlen(cl->q_) > cl->qthresh_))
                           return (0);
                   else
                           return (1);
           }
           if (cl->children_ != NULL) {
                   p = cl->children_;
                   while (p != NULL) {
                           if (!rmc_satisfied(p, now))
                                   return (0);
                           p = p->next_;
                   }
           }
   
           return (1);
   }
   
   /*
    * Return 1 if class 'cl' is under limit or can borrow from a parent,
    * 0 if overlimit.  As a side-effect, this routine will invoke the
    * class overlimit action if the class if overlimit.
    */
   
   static int
   rmc_under_limit(struct rm_class *cl, struct timeval *now)
   {
           rm_class_t      *p = cl;
           rm_class_t      *top;
           struct rm_ifdat *ifd = cl->ifdat_;
   
           ifd->borrowed_[ifd->qi_] = NULL;
           /*
            * If cl is the root class, then always return that it is
            * underlimit.  Otherwise, check to see if the class is underlimit.
            */
           if (cl->parent_ == NULL)
                   return (1);
   
           if (cl->sleeping_) {
                   if (TV_LT(now, &cl->undertime_))
                           return (0);
   
                   CALLOUT_STOP(&cl->callout_);
                   cl->sleeping_ = 0;
                   cl->undertime_.tv_sec = 0;
                   return (1);
           }
   
           top = NULL;
           while (cl->undertime_.tv_sec && TV_LT(now, &cl->undertime_)) {
                   if (((cl = cl->borrow_) == NULL) ||
                       (cl->depth_ > ifd->cutoff_)) {
   #ifdef ADJUST_CUTOFF
                           if (cl != NULL)
                                   /* cutoff is taking effect, just
                                      return false without calling
                                      the delay action. */
                                   return (0);
   #endif
   #ifdef BORROW_OFFTIME
                           /*
                            * check if the class can borrow offtime too.
                            * borrow offtime from the top of the borrow
                            * chain if the top class is not overloaded.
                            */
                           if (cl != NULL) {
                                   /* cutoff is taking effect, use this class as top. */
                                   top = cl;
                                   CBQTRACE(rmc_under_limit, 'ffou', ifd->cutoff_);
                           }
                           if (top != NULL && top->avgidle_ == top->minidle_)
                                   top = NULL;
                           p->overtime_ = *now;
                           (p->overlimit)(p, top);
   #else
                           p->overtime_ = *now;
                           (p->overlimit)(p, NULL);
   #endif
                           return (0);
                   }
                   top = cl;
           }
   
           if (cl != p)
                   ifd->borrowed_[ifd->qi_] = cl;
           return (1);
   }
   
   /*
    * _rmc_wrr_dequeue_next() - This is scheduler for WRR as opposed to
    *      Packet-by-packet round robin.
    *
    * The heart of the weighted round-robin scheduler, which decides which
    * class next gets to send a packet.  Highest priority first, then
    * weighted round-robin within priorites.
    *
    * Each able-to-send class gets to send until its byte allocation is
    * exhausted.  Thus, the active pointer is only changed after a class has
    * exhausted its allocation.
    *
    * If the scheduler finds no class that is underlimit or able to borrow,
    * then the first class found that had a nonzero queue and is allowed to
    * borrow gets to send.
    */
   
   static mbuf_t *
   _rmc_wrr_dequeue_next(struct rm_ifdat *ifd, int op)
   {
           struct rm_class *cl = NULL, *first = NULL;
           u_int            deficit;
           int              cpri;
           mbuf_t          *m;
           struct timeval   now;
   
           RM_GETTIME(now);
   
           /*
            * if the driver polls the top of the queue and then removes
            * the polled packet, we must return the same packet.
            */
           if (op == ALTDQ_REMOVE && ifd->pollcache_) {
                   cl = ifd->pollcache_;
                   cpri = cl->pri_;
                   if (ifd->efficient_) {
                           /* check if this class is overlimit */
                           if (cl->undertime_.tv_sec != 0 &&
                               rmc_under_limit(cl, &now) == 0)
                                   first = cl;
                   }
                   ifd->pollcache_ = NULL;
                   goto _wrr_out;
           }
           else {
                   /* mode == ALTDQ_POLL || pollcache == NULL */
                   ifd->pollcache_ = NULL;
                   ifd->borrowed_[ifd->qi_] = NULL;
           }
   #ifdef ADJUST_CUTOFF
    _again:
   #endif
           for (cpri = RM_MAXPRIO - 1; cpri >= 0; cpri--) {
                   if (ifd->na_[cpri] == 0)
                           continue;
                   deficit = 0;
                   /*
                    * Loop through twice for a priority level, if some class
                    * was unable to send a packet the first round because
                    * of the weighted round-robin mechanism.
                   * During the second loop at this level, deficit==2.
                   * (This second loop is not needed if for every class,
                   * "M[cl->pri_])" times "cl->allotment" is greater than
                   * the byte size for the largest packet in the class.)
                   */
   _wrr_loop:
                  cl = ifd->active_[cpri];
                  ASSERT(cl != NULL);
                  do {
                          if ((deficit < 2) && (cl->bytes_alloc_ <= 0))
                                  cl->bytes_alloc_ += cl->w_allotment_;
                          if (!qempty(cl->q_)) {
                                  if ((cl->undertime_.tv_sec == 0) ||
                                      rmc_under_limit(cl, &now)) {
                                          if (cl->bytes_alloc_ > 0 || deficit > 1)
                                                  goto _wrr_out;
  
                                          /* underlimit but no alloc */
                                          deficit = 1;
  #if 1
                                          ifd->borrowed_[ifd->qi_] = NULL;
  #endif
                                  }
                                  else if (first == NULL && cl->borrow_ != NULL)
                                          first = cl; /* borrowing candidate */
                          }
  
                          cl->bytes_alloc_ = 0;
                          cl = cl->peer_;
                  } while (cl != ifd->active_[cpri]);
  
                  if (deficit == 1) {
                          /* first loop found an underlimit class with deficit */
                          /* Loop on same priority level, with new deficit.  */
                          deficit = 2;
                          goto _wrr_loop;
                  }
          }
  
  #ifdef ADJUST_CUTOFF
          /*
           * no underlimit class found.  if cutoff is taking effect,
           * increase cutoff and try again.
           */
          if (first != NULL && ifd->cutoff_ < ifd->root_->depth_) {
                  ifd->cutoff_++;
                  CBQTRACE(_rmc_wrr_dequeue_next, 'ojda', ifd->cutoff_);
                  goto _again;
          }
  #endif /* ADJUST_CUTOFF */
          /*
           * If LINK_EFFICIENCY is turned on, then the first overlimit
           * class we encounter will send a packet if all the classes
           * of the link-sharing structure are overlimit.
           */
          reset_cutoff(ifd);
          CBQTRACE(_rmc_wrr_dequeue_next, 'otsr', ifd->cutoff_);
  
          if (!ifd->efficient_ || first == NULL)
                  return (NULL);
  
          cl = first;
          cpri = cl->pri_;
  #if 0   /* too time-consuming for nothing */
          if (cl->sleeping_)
                  CALLOUT_STOP(&cl->callout_);
          cl->sleeping_ = 0;
          cl->undertime_.tv_sec = 0;
  #endif
          ifd->borrowed_[ifd->qi_] = cl->borrow_;
          ifd->cutoff_ = cl->borrow_->depth_;
  
          /*
           * Deque the packet and do the book keeping...
           */
   _wrr_out:
          if (op == ALTDQ_REMOVE) {
                  m = _rmc_getq(cl);
                  if (m == NULL)
                          panic("_rmc_wrr_dequeue_next");
                  if (qempty(cl->q_))
                          ifd->na_[cpri]--;
  
                  /*
                   * Update class statistics and link data.
                   */
                  if (cl->bytes_alloc_ > 0)
                          cl->bytes_alloc_ -= m_pktlen(m);
  
                  if ((cl->bytes_alloc_ <= 0) || first == cl)
                          ifd->active_[cl->pri_] = cl->peer_;
                  else
                          ifd->active_[cl->pri_] = cl;
  
                  ifd->class_[ifd->qi_] = cl;
                  ifd->curlen_[ifd->qi_] = m_pktlen(m);
                  ifd->now_[ifd->qi_] = now;
                  ifd->qi_ = (ifd->qi_ + 1) % ifd->maxqueued_;
                  ifd->queued_++;
          } else {
                  /* mode == ALTDQ_PPOLL */
                  m = _rmc_pollq(cl);
                  ifd->pollcache_ = cl;
          }
          return (m);
  }
  
  /*
   * Dequeue & return next packet from the highest priority class that
   * has a packet to send & has enough allocation to send it.  This
   * routine is called by a driver whenever it needs a new packet to
   * output.
   */
  static mbuf_t *
  _rmc_prr_dequeue_next(struct rm_ifdat *ifd, int op)
  {
          mbuf_t          *m;
          int              cpri;
          struct rm_class *cl, *first = NULL;
          struct timeval   now;
  
          RM_GETTIME(now);
  
          /*
           * if the driver polls the top of the queue and then removes
           * the polled packet, we must return the same packet.
           */
          if (op == ALTDQ_REMOVE && ifd->pollcache_) {
                  cl = ifd->pollcache_;
                  cpri = cl->pri_;
                  ifd->pollcache_ = NULL;
                  goto _prr_out;
          } else {
                  /* mode == ALTDQ_POLL || pollcache == NULL */
                  ifd->pollcache_ = NULL;
                  ifd->borrowed_[ifd->qi_] = NULL;
          }
  #ifdef ADJUST_CUTOFF
   _again:
  #endif
          for (cpri = RM_MAXPRIO - 1; cpri >= 0; cpri--) {
                  if (ifd->na_[cpri] == 0)
                          continue;
                  cl = ifd->active_[cpri];
                  ASSERT(cl != NULL);
                  do {
                          if (!qempty(cl->q_)) {
                                  if ((cl->undertime_.tv_sec == 0) ||
                                      rmc_under_limit(cl, &now))
                                          goto _prr_out;
                                  if (first == NULL && cl->borrow_ != NULL)
                                          first = cl;
                          }
                          cl = cl->peer_;
                  } while (cl != ifd->active_[cpri]);
          }
  
  #ifdef ADJUST_CUTOFF
          /*
           * no underlimit class found.  if cutoff is taking effect, increase
           * cutoff and try again.
           */
          if (first != NULL && ifd->cutoff_ < ifd->root_->depth_) {
                  ifd->cutoff_++;
                  goto _again;
          }
  #endif /* ADJUST_CUTOFF */
          /*
           * If LINK_EFFICIENCY is turned on, then the first overlimit
           * class we encounter will send a packet if all the classes
           * of the link-sharing structure are overlimit.
           */
          reset_cutoff(ifd);
          if (!ifd->efficient_ || first == NULL)
                  return (NULL);
  
          cl = first;
          cpri = cl->pri_;
  #if 0   /* too time-consuming for nothing */
          if (cl->sleeping_)
                  CALLOUT_STOP(&cl->callout_);
          cl->sleeping_ = 0;
          cl->undertime_.tv_sec = 0;
  #endif
          ifd->borrowed_[ifd->qi_] = cl->borrow_;
          ifd->cutoff_ = cl->borrow_->depth_;
  
          /*
           * Deque the packet and do the book keeping...
           */
   _prr_out:
          if (op == ALTDQ_REMOVE) {
                  m = _rmc_getq(cl);
                  if (m == NULL)
                          panic("_rmc_prr_dequeue_next");
                  if (qempty(cl->q_))
                          ifd->na_[cpri]--;
  
                  ifd->active_[cpri] = cl->peer_;
  
                  ifd->class_[ifd->qi_] = cl;
                  ifd->curlen_[ifd->qi_] = m_pktlen(m);
                  ifd->now_[ifd->qi_] = now;
                  ifd->qi_ = (ifd->qi_ + 1) % ifd->maxqueued_;
                  ifd->queued_++;
          } else {
                  /* mode == ALTDQ_POLL */
                  m = _rmc_pollq(cl);
                  ifd->pollcache_ = cl;
          }
          return (m);
  }
  
  /*
   * mbuf_t *
   * rmc_dequeue_next(struct rm_ifdat *ifd, struct timeval *now) - this function
   *      is invoked by the packet driver to get the next packet to be
   *      dequeued and output on the link.  If WRR is enabled, then the
   *      WRR dequeue next routine will determine the next packet to sent.
   *      Otherwise, packet-by-packet round robin is invoked.
   *
   *      Returns:        NULL, if a packet is not available or if all
   *                      classes are overlimit.
   *
   *                      Otherwise, Pointer to the next packet.
   */
  
  mbuf_t *
  rmc_dequeue_next(struct rm_ifdat *ifd, int mode)
  {
          if (ifd->queued_ >= ifd->maxqueued_)
                  return (NULL);
          else if (ifd->wrr_)
                  return (_rmc_wrr_dequeue_next(ifd, mode));
          else
                  return (_rmc_prr_dequeue_next(ifd, mode));
  }
  
  /*
   * Update the utilization estimate for the packet that just completed.
   * The packet's class & the parent(s) of that class all get their
   * estimators updated.  This routine is called by the driver's output-
   * packet-completion interrupt service routine.
   */
  
  /*
   * a macro to approximate "divide by 1000" that gives 0.000999,
   * if a value has enough effective digits.
   * (on pentium, mul takes 9 cycles but div takes 46!)
   */
  #define NSEC_TO_USEC(t) (((t) >> 10) + ((t) >> 16) + ((t) >> 17))
  void
  rmc_update_class_util(struct rm_ifdat *ifd)
  {
          int              idle, avgidle, pktlen;
          int              pkt_time, tidle;
          rm_class_t      *cl, *borrowed;
          rm_class_t      *borrows;
          struct timeval  *nowp;
  
          /*
           * Get the most recent completed class.
           */
          if ((cl = ifd->class_[ifd->qo_]) == NULL)
                  return;
  
          pktlen = ifd->curlen_[ifd->qo_];
          borrowed = ifd->borrowed_[ifd->qo_];
          borrows = borrowed;
  
          PKTCNTR_ADD(&cl->stats_.xmit_cnt, pktlen);
  
          /*
           * Run estimator on class and its ancestors.
           */
          /*
           * rm_update_class_util is designed to be called when the
           * transfer is completed from a xmit complete interrupt,
           * but most drivers don't implement an upcall for that.
           * so, just use estimated completion time.
           * as a result, ifd->qi_ and ifd->qo_ are always synced.
           */
          nowp = &ifd->now_[ifd->qo_];
          /* get pkt_time (for link) in usec */
  #if 1  /* use approximation */
          pkt_time = ifd->curlen_[ifd->qo_] * ifd->ns_per_byte_;
          pkt_time = NSEC_TO_USEC(pkt_time);
  #else
          pkt_time = ifd->curlen_[ifd->qo_] * ifd->ns_per_byte_ / 1000;
  #endif
  #if 1 /* ALTQ4PPP */
          if (TV_LT(nowp, &ifd->ifnow_)) {
                  int iftime;
  
                  /*
                   * make sure the estimated completion time does not go
                   * too far.  it can happen when the link layer supports
                   * data compression or the interface speed is set to
                   * a much lower value.
                   */
                  TV_DELTA(&ifd->ifnow_, nowp, iftime);
                  if (iftime+pkt_time < ifd->maxiftime_) {
                          TV_ADD_DELTA(&ifd->ifnow_, pkt_time, &ifd->ifnow_);
                  } else {
                          TV_ADD_DELTA(nowp, ifd->maxiftime_, &ifd->ifnow_);
                  }
          } else {
                  TV_ADD_DELTA(nowp, pkt_time, &ifd->ifnow_);
          }
  #else
          if (TV_LT(nowp, &ifd->ifnow_)) {
                  TV_ADD_DELTA(&ifd->ifnow_, pkt_time, &ifd->ifnow_);
          } else {
                  TV_ADD_DELTA(nowp, pkt_time, &ifd->ifnow_);
          }
  #endif
  
          while (cl != NULL) {
                  TV_DELTA(&ifd->ifnow_, &cl->last_, idle);
                  if (idle >= 2000000)
                          /*
                           * this class is idle enough, reset avgidle.
                           * (TV_DELTA returns 2000000 us when delta is large.)
                           */
                          cl->avgidle_ = cl->maxidle_;
  
                  /* get pkt_time (for class) in usec */
  #if 1  /* use approximation */
                  pkt_time = pktlen * cl->ns_per_byte_;
                  pkt_time = NSEC_TO_USEC(pkt_time);
  #else
                  pkt_time = pktlen * cl->ns_per_byte_ / 1000;
  #endif
                  idle -= pkt_time;
  
                  avgidle = cl->avgidle_;
                  avgidle += idle - (avgidle >> RM_FILTER_GAIN);
                  cl->avgidle_ = avgidle;
  
                  /* Are we overlimit ? */
                  if (avgidle <= 0) {
                          CBQTRACE(rmc_update_class_util, 'milo', cl->stats_.handle);
  #if 1 /* ALTQ */
                          /*
                           * need some lower bound for avgidle, otherwise
                           * a borrowing class gets unbounded penalty.
                           */
                          if (avgidle < cl->minidle_)
                                  avgidle = cl->avgidle_ = cl->minidle_;
  #endif
                          /* set next idle to make avgidle 0 */
                          tidle = pkt_time +
                                  (((1 - RM_POWER) * avgidle) >> RM_FILTER_GAIN);
                          TV_ADD_DELTA(nowp, tidle, &cl->undertime_);
                          ++cl->stats_.over;
                  } else {
                          cl->avgidle_ =
                              (avgidle > cl->maxidle_) ? cl->maxidle_ : avgidle;
                          cl->undertime_.tv_sec = 0;
                          if (cl->sleeping_) {
                                  CALLOUT_STOP(&cl->callout_);
                                  cl->sleeping_ = 0;
                          }
                  }
  
                  if (borrows != NULL) {
                          if (borrows != cl)
                                  ++cl->stats_.borrows;
                          else
                                  borrows = NULL;
                  }
                  cl->last_ = ifd->ifnow_;
                  cl->last_pkttime_ = pkt_time;
  
  #if 1
                  if (cl->parent_ == NULL) {
                          /* take stats of root class */
                          PKTCNTR_ADD(&cl->stats_.xmit_cnt, pktlen);
                  }
  #endif
  
                  cl = cl->parent_;
          }
  
          /*
           * Check to see if cutoff needs to set to a new level.
           */
          cl = ifd->class_[ifd->qo_];
          if (borrowed && (ifd->cutoff_ >= borrowed->depth_)) {
  #if 1 /* ALTQ */
                  if ((qlen(cl->q_) <= 0) || TV_LT(nowp, &borrowed->undertime_)) {
                          rmc_tl_satisfied(ifd, nowp);
                          CBQTRACE(rmc_update_class_util, 'broe', ifd->cutoff_);
                  } else {
                          ifd->cutoff_ = borrowed->depth_;
                          CBQTRACE(rmc_update_class_util, 'ffob', borrowed->depth_);
                  }
  #else /* !ALTQ */
                  if ((qlen(cl->q_) <= 1) || TV_LT(&now, &borrowed->undertime_)) {
                          reset_cutoff(ifd);
  #ifdef notdef
                          rmc_tl_satisfied(ifd, &now);
  #endif
                          CBQTRACE(rmc_update_class_util, 'broe', ifd->cutoff_);
                  } else {
                          ifd->cutoff_ = borrowed->depth_;
                          CBQTRACE(rmc_update_class_util, 'ffob', borrowed->depth_);
                  }
  #endif /* !ALTQ */
          }
  
          /*
           * Release class slot
           */
          ifd->borrowed_[ifd->qo_] = NULL;
          ifd->class_[ifd->qo_] = NULL;
          ifd->qo_ = (ifd->qo_ + 1) % ifd->maxqueued_;
          ifd->queued_--;
  }
  
  /*
   * void
   * rmc_drop_action(struct rm_class *cl) - Generic (not protocol-specific)
   *      over-limit action routines.  These get invoked by rmc_under_limit()
   *      if a class with packets to send if over its bandwidth limit & can't
   *      borrow from a parent class.
   *
   *      Returns: NONE
   */
  
  static void
  rmc_drop_action(struct rm_class *cl)
  {
          struct rm_ifdat *ifd = cl->ifdat_;
  
          ASSERT(qlen(cl->q_) > 0);
          _rmc_dropq(cl);
          if (qempty(cl->q_))
                  ifd->na_[cl->pri_]--;
  }
  
  void rmc_dropall(struct rm_class *cl)
  {
          struct rm_ifdat *ifd = cl->ifdat_;
  
          if (!qempty(cl->q_)) {
                  _flushq(cl->q_);
  
                  ifd->na_[cl->pri_]--;
          }
  }
  
  #if (__FreeBSD_version > 300000)
  /* hzto() is removed from FreeBSD-3.0 */
  static int hzto(struct timeval *);
  
  static int
  hzto(tv)
          struct timeval *tv;
  {
          struct timeval t2;
  
          getmicrotime(&t2);
          t2.tv_sec = tv->tv_sec - t2.tv_sec;
          t2.tv_usec = tv->tv_usec - t2.tv_usec;
          return (tvtohz(&t2));
  }
  #endif /* __FreeBSD_version > 300000 */
  
  /*
   * void
   * rmc_delay_action(struct rm_class *cl) - This function is the generic CBQ
   *      delay action routine.  It is invoked via rmc_under_limit when the
   *      packet is discoverd to be overlimit.
   *
   *      If the delay action is result of borrow class being overlimit, then
   *      delay for the offtime of the borrowing class that is overlimit.
   *
   *      Returns: NONE
   */
  
  void
  rmc_delay_action(struct rm_class *cl, struct rm_class *borrow)
  {
          int     delay, t, extradelay;
  
          cl->stats_.overactions++;
          TV_DELTA(&cl->undertime_, &cl->overtime_, delay);
  #ifndef BORROW_OFFTIME
          delay += cl->offtime_;
  #endif
  
          if (!cl->sleeping_) {
                  CBQTRACE(rmc_delay_action, 'yled', cl->stats_.handle);
  #ifdef BORROW_OFFTIME
                  if (borrow != NULL)
                          extradelay = borrow->offtime_;
                  else
  #endif
                          extradelay = cl->offtime_;
  
  #ifdef ALTQ
                  /*
                   * XXX recalculate suspend time:
                   * current undertime is (tidle + pkt_time) calculated
                   * from the last transmission.
                   *      tidle: time required to bring avgidle back to 0
                   *      pkt_time: target waiting time for this class
                   * we need to replace pkt_time by offtime
                   */
                  extradelay -= cl->last_pkttime_;
  #endif
                  if (extradelay > 0) {
                          TV_ADD_DELTA(&cl->undertime_, extradelay, &cl->undertime_);
                          delay += extradelay;
                  }
  
                  cl->sleeping_ = 1;
                  cl->stats_.delays++;
  
                  /*
                   * Since packets are phased randomly with respect to the
                   * clock, 1 tick (the next clock tick) can be an arbitrarily
                   * short time so we have to wait for at least two ticks.
                   * NOTE:  If there's no other traffic, we need the timer as
                   * a 'backstop' to restart this class.
                   */
                  if (delay > tick * 2) {
                          /* FreeBSD rounds up the tick */
                          t = hzto(&cl->undertime_);
                  } else
                          t = 2;
                  CALLOUT_RESET(&cl->callout_, t, rmc_restart, cl);
          }
  }
  
  /*
   * void
   * rmc_restart() - is just a helper routine for rmc_delay_action -- it is
   *      called by the system timer code & is responsible checking if the
   *      class is still sleeping (it might have been restarted as a side
   *      effect of the queue scan on a packet arrival) and, if so, restarting
   *      output for the class.  Inspecting the class state & restarting output
   *      require locking the class structure.  In general the driver is
   *      responsible for locking but this is the only routine that is not
   *      called directly or indirectly from the interface driver so it has
   *      know about system locking conventions.  Under bsd, locking is done
   *      by raising IPL to splimp so that's what's implemented here.  On a
   *      different system this would probably need to be changed.
   *
   *      Returns:        NONE
   */
  
  static void
  rmc_restart(void *arg)
  {
          struct rm_class *cl = arg;
          struct rm_ifdat *ifd = cl->ifdat_;
          struct epoch_tracker et;
          int              s;
  
          s = splnet();
          NET_EPOCH_ENTER(et);
          IFQ_LOCK(ifd->ifq_);
          CURVNET_SET(ifd->ifq_->altq_ifp->if_vnet);
          if (cl->sleeping_) {
                  cl->sleeping_ = 0;
                  cl->undertime_.tv_sec = 0;
  
                  if (ifd->queued_ < ifd->maxqueued_ && ifd->restart != NULL) {
                          CBQTRACE(rmc_restart, 'trts', cl->stats_.handle);
                          (ifd->restart)(ifd->ifq_);
                  }
          }
          CURVNET_RESTORE();
          IFQ_UNLOCK(ifd->ifq_);
          NET_EPOCH_EXIT(et);
          splx(s);
  }
  
  /*
   * void
   * rmc_root_overlimit(struct rm_class *cl) - This the generic overlimit
   *      handling routine for the root class of the link sharing structure.
   *
   *      Returns: NONE
   */
  
  static void
  rmc_root_overlimit(struct rm_class *cl, struct rm_class *borrow)
  {
      panic("rmc_root_overlimit");
  }
  
  /*
   * Packet Queue handling routines.  Eventually, this is to localize the
   *      effects on the code whether queues are red queues or droptail
   *      queues.
   */
  
  static int
  _rmc_addq(rm_class_t *cl, mbuf_t *m)
  {
  #ifdef ALTQ_RIO
          if (q_is_rio(cl->q_))
                  return rio_addq((rio_t *)cl->red_, cl->q_, m, cl->pktattr_);
  #endif
  #ifdef ALTQ_RED
          if (q_is_red(cl->q_))
                  return red_addq(cl->red_, cl->q_, m, cl->pktattr_);
  #endif /* ALTQ_RED */
  #ifdef ALTQ_CODEL
          if (q_is_codel(cl->q_))
                  return codel_addq(cl->codel_, cl->q_, m);
  #endif
  
          if (cl->flags_ & RMCF_CLEARDSCP)
                  write_dsfield(m, cl->pktattr_, 0);
  
          _addq(cl->q_, m);
          return (0);
  }
  
  /* note: _rmc_dropq is not called for red */
  static void
  _rmc_dropq(rm_class_t *cl)
  {
          mbuf_t  *m;
  
          if ((m = _getq(cl->q_)) != NULL)
                  m_freem(m);
  }
  
  static mbuf_t *
  _rmc_getq(rm_class_t *cl)
  {
  #ifdef ALTQ_RIO
          if (q_is_rio(cl->q_))
                  return rio_getq((rio_t *)cl->red_, cl->q_);
  #endif
  #ifdef ALTQ_RED
          if (q_is_red(cl->q_))
                  return red_getq(cl->red_, cl->q_);
  #endif
  #ifdef ALTQ_CODEL
          if (q_is_codel(cl->q_))
                  return codel_getq(cl->codel_, cl->q_);
  #endif
          return _getq(cl->q_);
  }
  
  static mbuf_t *
  _rmc_pollq(rm_class_t *cl)
  {
          return qhead(cl->q_);
  }
  
  #ifdef CBQ_TRACE
  
  struct cbqtrace          cbqtrace_buffer[NCBQTRACE+1];
  struct cbqtrace         *cbqtrace_ptr = NULL;
  int                      cbqtrace_count;
  
  /*
   * DDB hook to trace cbq events:
   *  the last 1024 events are held in a circular buffer.
   *  use "call cbqtrace_dump(N)" to display 20 events from Nth event.
   */
  void cbqtrace_dump(int);
  static char *rmc_funcname(void *);
  
  static struct rmc_funcs {
          void    *func;
          char    *name;
  } rmc_funcs[] =
  {
          rmc_init,               "rmc_init",
          rmc_queue_packet,       "rmc_queue_packet",
          rmc_under_limit,        "rmc_under_limit",
          rmc_update_class_util,  "rmc_update_class_util",
          rmc_delay_action,       "rmc_delay_action",
          rmc_restart,            "rmc_restart",
          _rmc_wrr_dequeue_next,  "_rmc_wrr_dequeue_next",
          NULL,                   NULL
  };
  
  static char *rmc_funcname(void *func)
  {
          struct rmc_funcs *fp;
  
          for (fp = rmc_funcs; fp->func != NULL; fp++)
                  if (fp->func == func)
                          return (fp->name);
          return ("unknown");
  }
  
  void cbqtrace_dump(int counter)
  {
          int      i, *p;
          char    *cp;
  
          counter = counter % NCBQTRACE;
          p = (int *)&cbqtrace_buffer[counter];
  
          for (i=0; i<20; i++) {
                  printf("[0x%x] ", *p++);
                  printf("%s: ", rmc_funcname((void *)*p++));
                  cp = (char *)p++;
                  printf("%c%c%c%c: ", cp[0], cp[1], cp[2], cp[3]);
                  printf("%d\n",*p++);
  
                  if (p >= (int *)&cbqtrace_buffer[NCBQTRACE])
                          p = (int *)cbqtrace_buffer;
          }
  }
  #endif /* CBQ_TRACE */
  #endif /* ALTQ_CBQ */
  
  #if defined(ALTQ_CBQ) || defined(ALTQ_RED) || defined(ALTQ_RIO) || \
      defined(ALTQ_HFSC) || defined(ALTQ_PRIQ) || defined(ALTQ_CODEL)
  #if !defined(__GNUC__) || defined(ALTQ_DEBUG)
  
  void
  _addq(class_queue_t *q, mbuf_t *m)
  {
          mbuf_t  *m0;
  
          if ((m0 = qtail(q)) != NULL)
                  m->m_nextpkt = m0->m_nextpkt;
          else
                  m0 = m;
          m0->m_nextpkt = m;
          qtail(q) = m;
          qlen(q)++;
  }
  
  mbuf_t *
  _getq(class_queue_t *q)
  {
          mbuf_t  *m, *m0;
  
          if ((m = qtail(q)) == NULL)
                  return (NULL);
          if ((m0 = m->m_nextpkt) != m)
                  m->m_nextpkt = m0->m_nextpkt;
          else {
                  ASSERT(qlen(q) == 1);
                  qtail(q) = NULL;
          }
          qlen(q)--;
          m0->m_nextpkt = NULL;
          return (m0);
  }
  
  /* drop a packet at the tail of the queue */
  mbuf_t *
  _getq_tail(class_queue_t *q)
  {
          mbuf_t  *m, *m0, *prev;
  
          if ((m = m0 = qtail(q)) == NULL)
                  return NULL;
          do {
                  prev = m0;
                  m0 = m0->m_nextpkt;
          } while (m0 != m);
          prev->m_nextpkt = m->m_nextpkt;
          if (prev == m)  {
                  ASSERT(qlen(q) == 1);
                  qtail(q) = NULL;
          } else
                  qtail(q) = prev;
          qlen(q)--;
          m->m_nextpkt = NULL;
          return (m);
  }
  
  /* randomly select a packet in the queue */
  mbuf_t *
  _getq_random(class_queue_t *q)
  {
          struct mbuf     *m;
          int              i, n;
  
          if ((m = qtail(q)) == NULL)
                  return NULL;
          if (m->m_nextpkt == m) {
                  ASSERT(qlen(q) == 1);
                  qtail(q) = NULL;
          } else {
                  struct mbuf *prev = NULL;
  
                  n = arc4random() % qlen(q) + 1;
                  for (i = 0; i < n; i++) {
                          prev = m;
                          m = m->m_nextpkt;
                  }
                  prev->m_nextpkt = m->m_nextpkt;
                  if (m == qtail(q))
                          qtail(q) = prev;
          }
          qlen(q)--;
          m->m_nextpkt = NULL;
          return (m);
  }
  
  void
  _removeq(class_queue_t *q, mbuf_t *m)
  {
          mbuf_t  *m0, *prev;
  
          m0 = qtail(q);
          do {
                  prev = m0;
                  m0 = m0->m_nextpkt;
          } while (m0 != m);
          prev->m_nextpkt = m->m_nextpkt;
          if (prev == m)
                  qtail(q) = NULL;
          else if (qtail(q) == m)
                  qtail(q) = prev;
          qlen(q)--;
  }
  
  void
  _flushq(class_queue_t *q)
  {
          mbuf_t *m;
  
          while ((m = _getq(q)) != NULL)
                  m_freem(m);
          ASSERT(qlen(q) == 0);
  }
  
  #endif /* !__GNUC__ || ALTQ_DEBUG */
  #endif /* ALTQ_CBQ || ALTQ_RED || ALTQ_RIO || ALTQ_HFSC || ALTQ_PRIQ */

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