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aba5acdf SH |
1 | /* |
2 | * tc_cbq.c CBQ 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 <syslog.h> | |
17 | #include <fcntl.h> | |
18 | #include <math.h> | |
19 | #include <sys/socket.h> | |
20 | #include <netinet/in.h> | |
21 | #include <arpa/inet.h> | |
22 | #include <string.h> | |
23 | ||
24 | #include "tc_core.h" | |
25 | #include "tc_cbq.h" | |
26 | ||
27 | unsigned tc_cbq_calc_maxidle(unsigned bndw, unsigned rate, unsigned avpkt, | |
28 | int ewma_log, unsigned maxburst) | |
29 | { | |
30 | double maxidle; | |
31 | double g = 1.0 - 1.0/(1<<ewma_log); | |
32 | double xmt = (double)avpkt/bndw; | |
33 | ||
34 | maxidle = xmt*(1-g); | |
35 | if (bndw != rate && maxburst) { | |
36 | double vxmt = (double)avpkt/rate - xmt; | |
37 | vxmt *= (pow(g, -(double)maxburst) - 1); | |
38 | if (vxmt > maxidle) | |
39 | maxidle = vxmt; | |
40 | } | |
8f34caaf | 41 | return tc_core_time2tick(maxidle*(1<<ewma_log)*TIME_UNITS_PER_SEC); |
aba5acdf SH |
42 | } |
43 | ||
44 | unsigned tc_cbq_calc_offtime(unsigned bndw, unsigned rate, unsigned avpkt, | |
45 | int ewma_log, unsigned minburst) | |
46 | { | |
47 | double g = 1.0 - 1.0/(1<<ewma_log); | |
48 | double offtime = (double)avpkt/rate - (double)avpkt/bndw; | |
49 | ||
50 | if (minburst == 0) | |
51 | return 0; | |
52 | if (minburst == 1) | |
53 | offtime *= pow(g, -(double)minburst) - 1; | |
54 | else | |
55 | offtime *= 1 + (pow(g, -(double)(minburst-1)) - 1)/(1-g); | |
8f34caaf | 56 | return tc_core_time2tick(offtime*TIME_UNITS_PER_SEC); |
aba5acdf | 57 | } |