1 /*
2 * PIE - Proportional Integral controller Enhanced AQM algorithm.
3 *
4 * Copyright (C) 2016 Centre for Advanced Internet Architectures,
5 * Swinburne University of Technology, Melbourne, Australia.
6 * Portions of this code were made possible in part by a gift from
7 * The Comcast Innovation Fund.
8 * Implemented by Rasool Al-Saadi <ralsaadi@swin.edu.au>
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #ifndef _IP_DN_AQM_PIE_H
33 #define _IP_DN_AQM_PIE_H
34
35 #define DN_AQM_PIE 2
36 #define PIE_DQ_THRESHOLD_BITS 14
37 /* 2^14 =16KB */
38 #define PIE_DQ_THRESHOLD (1L << PIE_DQ_THRESHOLD_BITS)
39 #define MEAN_PKTSIZE 800
40
41 /* 31-bits because random() generates range from 0->(2**31)-1 */
42 #define PIE_PROB_BITS 31
43 #define PIE_MAX_PROB ((1LL<<PIE_PROB_BITS) -1)
44
45 /* for 16-bits, we have 3-bits for integer part and 13-bits for fraction */
46 #define PIE_FIX_POINT_BITS 13
47 #define PIE_SCALE (1L<<PIE_FIX_POINT_BITS)
48
49 /* PIE options */
50 enum {
51 PIE_ECN_ENABLED =1,
52 PIE_CAPDROP_ENABLED = 2,
53 PIE_ON_OFF_MODE_ENABLED = 4,
54 PIE_DEPRATEEST_ENABLED = 8,
55 PIE_DERAND_ENABLED = 16
56 };
57
58 /* PIE parameters */
59 struct dn_aqm_pie_parms {
60 aqm_time_t qdelay_ref; /* AQM Latency Target (default: 15ms) */
61 aqm_time_t tupdate; /* a period to calculate drop probability (default:15ms) */
62 aqm_time_t max_burst; /* AQM Max Burst Allowance (default: 150ms) */
63 uint16_t max_ecnth; /*AQM Max ECN Marking Threshold (default: 10%) */
64 uint16_t alpha; /* (default: 1/8) */
65 uint16_t beta; /* (default: 1+1/4) */
66 uint32_t flags; /* PIE options */
67 };
68
69 /* PIE status variables */
70 struct pie_status{
71 struct callout aqm_pie_callout;
72 aqm_time_t burst_allowance;
73 uint32_t drop_prob;
74 aqm_time_t current_qdelay;
75 aqm_time_t qdelay_old;
76 uint64_t accu_prob;
77 aqm_time_t measurement_start;
78 aqm_time_t avg_dq_time;
79 uint32_t dq_count;
80 uint32_t sflags;
81 struct dn_aqm_pie_parms *parms; /* pointer to PIE configurations */
82 /* pointer to parent queue of FQ-PIE sub-queues, or queue of owner fs. */
83 struct dn_queue *pq;
84 struct mtx lock_mtx;
85 uint32_t one_third_q_size; /* 1/3 of queue size, for speed optization */
86 };
87
88 enum {
89 ENQUE = 1,
90 DROP,
91 MARKECN
92 };
93
94 /* PIE current state */
95 enum {
96 PIE_ACTIVE = 1,
97 PIE_INMEASUREMENT = 2
98 };
99
100 /*
101 * Check if eneque should drop packet to control delay or not based on
102 * PIe algorithm.
103 * return DROP if it is time to drop or ENQUE otherwise.
104 * This function is used by PIE and FQ-PIE.
105 */
106 __inline static int
drop_early(struct pie_status * pst,uint32_t qlen)107 drop_early(struct pie_status *pst, uint32_t qlen)
108 {
109 struct dn_aqm_pie_parms *pprms;
110
111 pprms = pst->parms;
112
113 /* queue is not congested */
114
115 if ((pst->qdelay_old < (pprms->qdelay_ref >> 1)
116 && pst->drop_prob < PIE_MAX_PROB / 5 )
117 || qlen <= 2 * MEAN_PKTSIZE)
118 return ENQUE;
119
120 if (pst->drop_prob == 0)
121 pst->accu_prob = 0;
122
123 /* increment accu_prob */
124 if (pprms->flags & PIE_DERAND_ENABLED)
125 pst->accu_prob += pst->drop_prob;
126
127 /* De-randomize option
128 * if accu_prob < 0.85 -> enqueue
129 * if accu_prob>8.5 ->drop
130 * between 0.85 and 8.5 || !De-randomize --> drop on prob
131 *
132 * (0.85 = 17/20 ,8.5 = 17/2)
133 */
134 if (pprms->flags & PIE_DERAND_ENABLED) {
135 if(pst->accu_prob < (uint64_t) (PIE_MAX_PROB * 17 / 20))
136 return ENQUE;
137 if( pst->accu_prob >= (uint64_t) (PIE_MAX_PROB * 17 / 2))
138 return DROP;
139 }
140
141 if (random() < pst->drop_prob) {
142 pst->accu_prob = 0;
143 return DROP;
144 }
145
146 return ENQUE;
147 }
148
149 #endif
150