tc/tc_red.c

   1 /*
   2  * tc_red.c             RED maintanance routines.
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  *
  11  */
  12
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <unistd.h>
  16 #include <fcntl.h>
  17 #include <math.h>
  18 #include <sys/socket.h>
  19 #include <netinet/in.h>
  20 #include <arpa/inet.h>
  21 #include <string.h>
  22
  23 #include "utils.h"
  24 #include "tc_core.h"
  25 #include "tc_util.h"
  26 #include "tc_red.h"
  27
  28 /*
  29    Plog = log(prob/(qmax - qmin))
  30  */
  31 int tc_red_eval_P(unsigned int qmin, unsigned int qmax, double prob)
  32 {
  33         int i = qmax - qmin;
  34
  35         if (!i)
  36                 return 0;
  37         if (i < 0)
  38                 return -1;
  39
  40         prob /= i;
  41
  42         for (i = 0; i < 32; i++) {
  43                 if (prob > 1.0)
  44                         break;
  45                 prob *= 2;
  46         }
  47         if (i >= 32)
  48                 return -1;
  49         return i;
  50 }
  51
  52 /*
  53    burst + 1 - qmin/avpkt < (1-(1-W)^burst)/W
  54  */
  55
  56 int tc_red_eval_ewma(unsigned int qmin, unsigned int burst, unsigned int avpkt)
  57 {
  58         int wlog = 1;
  59         double W = 0.5;
  60         double a = (double)burst + 1 - (double)qmin/avpkt;
  61
  62         if (a < 1.0) {
  63                 fprintf(stderr, "tc_red_eval_ewma() burst %u is too small ? Try burst %u\n",
  64                                 burst, 1 + qmin/avpkt);
  65                 return -1;
  66         }
  67         for (wlog = 1; wlog < 32; wlog++, W /= 2) {
  68                 if (a <= (1 - pow(1-W, burst))/W)
  69                         return wlog;
  70         }
  71         return -1;
  72 }
  73
  74 /*
  75    Stab[t>>Scell_log] = -log(1-W) * t/xmit_time
  76  */
  77
  78 int tc_red_eval_idle_damping(int Wlog, unsigned int avpkt, unsigned int bps, __u8 *sbuf)
  79 {
  80         double xmit_time = tc_calc_xmittime(bps, avpkt);
  81         double lW = -log(1.0 - 1.0/(1<<Wlog))/xmit_time;
  82         double maxtime = 31/lW;
  83         int clog;
  84         int i;
  85
  86         for (clog = 0; clog < 32; clog++) {
  87                 if (maxtime/(1<<clog) < 512)
  88                         break;
  89         }
  90         if (clog >= 32)
  91                 return -1;
  92
  93         sbuf[0] = 0;
  94         for (i = 1; i < 255; i++) {
  95                 sbuf[i] = (i<<clog)*lW;
  96                 if (sbuf[i] > 31)
  97                         sbuf[i] = 31;
  98         }
  99         sbuf[255] = 31;
 100         return clog;
 101 }
 102
 103 void tc_red_print_flags(__u32 flags)
 104 {
 105         if (flags & TC_RED_ECN)
 106                 print_bool(PRINT_ANY, "ecn", "ecn ", true);
 107         else
 108                 print_bool(PRINT_ANY, "ecn", NULL, false);
 109
 110         if (flags & TC_RED_HARDDROP)
 111                 print_bool(PRINT_ANY, "harddrop", "harddrop ", true);
 112         else
 113                 print_bool(PRINT_ANY, "harddrop", NULL, false);
 114
 115         if (flags & TC_RED_ADAPTATIVE)
 116                 print_bool(PRINT_ANY, "adaptive", "adaptive ", true);
 117         else
 118                 print_bool(PRINT_ANY, "adaptive", NULL, false);
 119 }