summaryrefslogtreecommitdiffstats
path: root/lib/librte_sched/rte_red.c
blob: fdf40576189d2d287db6248c22002daf097bb4e8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
/*-
 *   BSD LICENSE
 *
 *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
 *   All rights reserved.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *     * Neither the name of Intel Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <math.h>
#include "rte_red.h"
#include <rte_random.h>
#include <rte_common.h>

#ifdef __INTEL_COMPILER
#pragma warning(disable:2259) /* conversion may lose significant bits */
#endif

static int rte_red_init_done = 0;     /**< Flag to indicate that global initialisation is done */
uint32_t rte_red_rand_val = 0;        /**< Random value cache */
uint32_t rte_red_rand_seed = 0;       /**< Seed for random number generation */

/**
 * table[i] = log2(1-Wq) * Scale * -1
 *       Wq = 1/(2^i)
 */
uint16_t rte_red_log2_1_minus_Wq[RTE_RED_WQ_LOG2_NUM];

/**
 * table[i] = 2^(i/16) * Scale
 */
uint16_t rte_red_pow2_frac_inv[16];

/**
 * @brief Initialize tables used to compute average
 *        queue size when queue is empty.
 */
static void
__rte_red_init_tables(void)
{
	uint32_t i = 0;
	double scale = 0.0;
	double table_size = 0.0;

	scale = (double)(1 << RTE_RED_SCALING);
	table_size = (double)(RTE_DIM(rte_red_pow2_frac_inv));

	for (i = 0; i < RTE_DIM(rte_red_pow2_frac_inv); i++) {
		double m = (double)i;

		rte_red_pow2_frac_inv[i] = (uint16_t) round(scale / pow(2, m / table_size));
	}

	scale = 1024.0;

	RTE_RED_ASSERT(RTE_RED_WQ_LOG2_NUM == RTE_DIM(rte_red_log2_1_minus_Wq));

	for (i = RTE_RED_WQ_LOG2_MIN; i <= RTE_RED_WQ_LOG2_MAX; i++) {
		double n = (double)i;
		double Wq = pow(2, -n);
		uint32_t index = i - RTE_RED_WQ_LOG2_MIN;

		rte_red_log2_1_minus_Wq[index] = (uint16_t) round(-1.0 * scale * log2(1.0 - Wq));
		/**
		* Table entry of zero, corresponds to a Wq of zero
		* which is not valid (avg would remain constant no
		* matter how long the queue is empty). So we have
		* to check for zero and round up to one.
		*/
		if (rte_red_log2_1_minus_Wq[index] == 0) {
			rte_red_log2_1_minus_Wq[index] = 1;
		}
	}
}

int
rte_red_rt_data_init(struct rte_red *red)
{
	if (red == NULL)
		return -1;

	red->avg = 0;
	red->count = 0;
	red->q_time = 0;
	return 0;
}

int
rte_red_config_init(struct rte_red_config *red_cfg,
	const uint16_t wq_log2,
	const uint16_t min_th,
	const uint16_t max_th,
	const uint16_t maxp_inv)
{
	if (red_cfg == NULL) {
		return -1;
	}
	if (max_th > RTE_RED_MAX_TH_MAX) {
		return -2;
	}
	if (min_th >= max_th) {
		return -3;
	}
	if (wq_log2 > RTE_RED_WQ_LOG2_MAX) {
		return -4;
	}
	if (wq_log2 < RTE_RED_WQ_LOG2_MIN) {
		return -5;
	}
	if (maxp_inv < RTE_RED_MAXP_INV_MIN) {
		return -6;
	}
	if (maxp_inv > RTE_RED_MAXP_INV_MAX) {
		return -7;
	}

	/**
	 *  Initialize the RED module if not already done
	 */
	if (!rte_red_init_done) {
		rte_red_rand_seed = rte_rand();
		rte_red_rand_val = rte_fast_rand();
		__rte_red_init_tables();
		rte_red_init_done = 1;
	}

	red_cfg->min_th = ((uint32_t) min_th) << (wq_log2 + RTE_RED_SCALING);
	red_cfg->max_th = ((uint32_t) max_th) << (wq_log2 + RTE_RED_SCALING);
	red_cfg->pa_const = (2 * (max_th - min_th) * maxp_inv) << RTE_RED_SCALING;
	red_cfg->maxp_inv = maxp_inv;
	red_cfg->wq_log2 = wq_log2;

	return 0;
}