FreeBSD/Linux Kernel Cross Reference
sys/netpfil/ipfw/dn_aqm_pie.h

     /*
      * PIE - Proportional Integral controller Enhanced AQM algorithm.
      *
      * $FreeBSD$
      * 
      * Copyright (C) 2016 Centre for Advanced Internet Architectures,
      *  Swinburne University of Technology, Melbourne, Australia.
      * Portions of this code were made possible in part by a gift from 
      *  The Comcast Innovation Fund.
     * Implemented by Rasool Al-Saadi <ralsaadi@swin.edu.au>
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    #ifndef _IP_DN_AQM_PIE_H
    #define _IP_DN_AQM_PIE_H
    
    #define DN_AQM_PIE 2
    #define PIE_DQ_THRESHOLD_BITS 14
    /* 2^14 =16KB */
    #define PIE_DQ_THRESHOLD (1L << PIE_DQ_THRESHOLD_BITS) 
    #define MEAN_PKTSIZE 800
    
    /* 31-bits because random() generates range from 0->(2**31)-1 */
    #define PIE_PROB_BITS 31
    #define PIE_MAX_PROB ((1LL<<PIE_PROB_BITS) -1)
    
    /* for 16-bits, we have 3-bits for integer part and 13-bits for fraction */
    #define PIE_FIX_POINT_BITS 13
    #define PIE_SCALE (1L<<PIE_FIX_POINT_BITS)
    
    /* PIE options */
    enum {
            PIE_ECN_ENABLED =1,
            PIE_CAPDROP_ENABLED = 2,
            PIE_ON_OFF_MODE_ENABLED = 4,
            PIE_DEPRATEEST_ENABLED = 8,
            PIE_DERAND_ENABLED = 16
    };
    
    /* PIE parameters */
    struct dn_aqm_pie_parms {
            aqm_time_t      qdelay_ref;     /* AQM Latency Target (default: 15ms) */
            aqm_time_t      tupdate;                /* a period to calculate drop probability (default:15ms) */
            aqm_time_t      max_burst;      /* AQM Max Burst Allowance (default: 150ms) */
            uint16_t        max_ecnth;      /*AQM Max ECN Marking Threshold (default: 10%) */
            uint16_t        alpha;                  /* (default: 1/8) */
            uint16_t        beta;                   /* (default: 1+1/4) */
            uint32_t        flags;                  /* PIE options */
    };
    
    /* PIE status variables */
    struct pie_status{
            struct callout  aqm_pie_callout;
            aqm_time_t      burst_allowance;
            uint32_t        drop_prob;
            aqm_time_t      current_qdelay;
            aqm_time_t      qdelay_old;
            uint64_t        accu_prob;
            aqm_time_t      measurement_start;
            aqm_time_t      avg_dq_time;
            uint32_t        dq_count;
            uint32_t        sflags;
            struct dn_aqm_pie_parms *parms; /* pointer to PIE configurations */
            /* pointer to parent queue of FQ-PIE sub-queues, or  queue of owner fs. */
            struct dn_queue *pq;    
            struct mtx      lock_mtx;
            uint32_t one_third_q_size; /* 1/3 of queue size, for speed optization */
    };
    
    enum { 
            ENQUE = 1,
            DROP,
            MARKECN
    };
    
    /* PIE current state */
    enum { 
            PIE_ACTIVE = 1,
            PIE_INMEASUREMENT = 2
   };
   
   /* 
    * Check if eneque should drop packet to control delay or not based on
    * PIe algorithm.
    * return  DROP if it is time to drop or  ENQUE otherwise.
    * This function is used by PIE and FQ-PIE.
    */
   __inline static int
   drop_early(struct pie_status *pst, uint32_t qlen)
   {
           struct dn_aqm_pie_parms *pprms;
   
           pprms = pst->parms;
   
           /* queue is not congested */
   
           if ((pst->qdelay_old < (pprms->qdelay_ref >> 1)
                   && pst->drop_prob < PIE_MAX_PROB / 5 )
                   ||  qlen <= 2 * MEAN_PKTSIZE)
                   return ENQUE;
   
           if (pst->drop_prob == 0)
                   pst->accu_prob = 0;
   
           /* increment accu_prob */
           if (pprms->flags & PIE_DERAND_ENABLED)
                   pst->accu_prob += pst->drop_prob;
   
           /* De-randomize option 
            * if accu_prob < 0.85 -> enqueue
            * if accu_prob>8.5 ->drop
            * between 0.85 and 8.5 || !De-randomize --> drop on prob
            * 
            * (0.85 = 17/20 ,8.5 = 17/2)
            */
           if (pprms->flags & PIE_DERAND_ENABLED) {
                   if(pst->accu_prob < (uint64_t) (PIE_MAX_PROB * 17 / 20))
                           return ENQUE;
                    if( pst->accu_prob >= (uint64_t) (PIE_MAX_PROB * 17 / 2))
                           return DROP;
           }
   
           if (random() < pst->drop_prob) {
                   pst->accu_prob = 0;
                   return DROP;
           }
   
           return ENQUE;
   }
   
   #endif

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