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aba5acdf SH |
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> | |
aba5acdf SH |
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 "tc_core.h" | |
24 | #include "tc_red.h" | |
25 | ||
26 | /* | |
27 | Plog = log(prob/(qmax - qmin)) | |
28 | */ | |
32a121cb | 29 | int tc_red_eval_P(unsigned int qmin, unsigned int qmax, double prob) |
aba5acdf SH |
30 | { |
31 | int i = qmax - qmin; | |
32 | ||
e0850bde JK |
33 | if (!i) |
34 | return 0; | |
35 | if (i < 0) | |
aba5acdf SH |
36 | return -1; |
37 | ||
38 | prob /= i; | |
39 | ||
32a121cb | 40 | for (i = 0; i < 32; i++) { |
aba5acdf SH |
41 | if (prob > 1.0) |
42 | break; | |
43 | prob *= 2; | |
44 | } | |
32a121cb | 45 | if (i >= 32) |
aba5acdf SH |
46 | return -1; |
47 | return i; | |
48 | } | |
49 | ||
50 | /* | |
51 | burst + 1 - qmin/avpkt < (1-(1-W)^burst)/W | |
52 | */ | |
53 | ||
32a121cb | 54 | int tc_red_eval_ewma(unsigned int qmin, unsigned int burst, unsigned int avpkt) |
aba5acdf SH |
55 | { |
56 | int wlog = 1; | |
57 | double W = 0.5; | |
58 | double a = (double)burst + 1 - (double)qmin/avpkt; | |
59 | ||
0cf67ead | 60 | if (a < 1.0) { |
32a121cb SH |
61 | fprintf(stderr, "tc_red_eval_ewma() burst %u is too small ? Try burst %u\n", |
62 | burst, 1 + qmin/avpkt); | |
aba5acdf | 63 | return -1; |
0cf67ead | 64 | } |
32a121cb | 65 | for (wlog = 1; wlog < 32; wlog++, W /= 2) { |
aba5acdf SH |
66 | if (a <= (1 - pow(1-W, burst))/W) |
67 | return wlog; | |
68 | } | |
69 | return -1; | |
70 | } | |
71 | ||
72 | /* | |
73 | Stab[t>>Scell_log] = -log(1-W) * t/xmit_time | |
74 | */ | |
75 | ||
32a121cb | 76 | int tc_red_eval_idle_damping(int Wlog, unsigned int avpkt, unsigned int bps, __u8 *sbuf) |
aba5acdf | 77 | { |
476daa72 | 78 | double xmit_time = tc_calc_xmittime(bps, avpkt); |
aba5acdf SH |
79 | double lW = -log(1.0 - 1.0/(1<<Wlog))/xmit_time; |
80 | double maxtime = 31/lW; | |
81 | int clog; | |
82 | int i; | |
aba5acdf | 83 | |
32a121cb | 84 | for (clog = 0; clog < 32; clog++) { |
aba5acdf SH |
85 | if (maxtime/(1<<clog) < 512) |
86 | break; | |
87 | } | |
88 | if (clog >= 32) | |
89 | return -1; | |
90 | ||
91 | sbuf[0] = 0; | |
32a121cb | 92 | for (i = 1; i < 255; i++) { |
aba5acdf SH |
93 | sbuf[i] = (i<<clog)*lW; |
94 | if (sbuf[i] > 31) | |
95 | sbuf[i] = 31; | |
96 | } | |
97 | sbuf[255] = 31; | |
98 | return clog; | |
99 | } |