tc_core.c revision 57a800d45a5f8f46c9ce4950599f17545413c82d 
1/*
2 * tc_core.c		TC core library.
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
26static double tick_in_usec = 1;
27static double clock_factor = 1;
28
29int tc_core_time2big(long time)
30{
31	__u64 t = time;
32
33	t *= tick_in_usec;
34	return (t >> 32) != 0;
35}
36
37
38unsigned tc_core_time2tick(unsigned time)
39{
40	return time*tick_in_usec;
41}
42
43unsigned tc_core_tick2time(unsigned tick)
44{
45	return tick/tick_in_usec;
46}
47
48unsigned tc_core_time2ktime(unsigned time)
49{
50	return time * clock_factor;
51}
52
53unsigned tc_core_ktime2time(unsigned ktime)
54{
55	return ktime / clock_factor;
56}
57
58unsigned tc_calc_xmittime(unsigned rate, unsigned size)
59{
60	return tc_core_time2tick(TIME_UNITS_PER_SEC*((double)size/rate));
61}
62
63unsigned tc_calc_xmitsize(unsigned rate, unsigned ticks)
64{
65	return ((double)rate*tc_core_tick2time(ticks))/TIME_UNITS_PER_SEC;
66}
67
68/*
69   rtab[pkt_len>>cell_log] = pkt_xmit_time
70 */
71
72int tc_calc_rtable(unsigned bps, __u32 *rtab, int cell_log, unsigned mtu,
73		   unsigned mpu)
74{
75	int i;
76	unsigned overhead = (mpu >> 8) & 0xFF;
77	mpu = mpu & 0xFF;
78
79	if (mtu == 0)
80		mtu = 2047;
81
82	if (cell_log < 0) {
83		cell_log = 0;
84		while ((mtu>>cell_log) > 255)
85			cell_log++;
86	}
87	for (i=0; i<256; i++) {
88		unsigned sz = (i<<cell_log);
89		if (overhead)
90			sz += overhead;
91		if (sz < mpu)
92			sz = mpu;
93		rtab[i] = tc_calc_xmittime(bps, sz);
94	}
95	return cell_log;
96}
97
98int tc_core_init()
99{
100	FILE *fp;
101	__u32 clock_res;
102	__u32 t2us;
103	__u32 us2t;
104
105	fp = fopen("/proc/net/psched", "r");
106	if (fp == NULL)
107		return -1;
108
109	if (fscanf(fp, "%08x%08x%08x", &t2us, &us2t, &clock_res) != 3) {
110		fclose(fp);
111		return -1;
112	}
113	fclose(fp);
114
115	/* compatibility hack: for old iproute binaries (ignoring
116	 * the kernel clock resolution) the kernel advertises a
117	 * tick multiplier of 1000 in case of nano-second resolution,
118	 * which really is 1. */
119	if (clock_res == 1000000000)
120		t2us = us2t;
121
122	clock_factor  = (double)clock_res / TIME_UNITS_PER_SEC;
123	tick_in_usec = (double)t2us / us2t * clock_factor;
124	return 0;
125}
126