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
tc_cbq_calc_maxidle(unsigned bndw,unsigned rate,unsigned avpkt,int ewma_log,unsigned maxburst)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 }
41 return tc_core_time2tick(maxidle*(1<<ewma_log)*TIME_UNITS_PER_SEC);
42 }
43
tc_cbq_calc_offtime(unsigned bndw,unsigned rate,unsigned avpkt,int ewma_log,unsigned minburst)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);
56 return tc_core_time2tick(offtime*TIME_UNITS_PER_SEC);
57 }
58