1 #ifndef __NET_SCHED_CODEL_H 2 #define __NET_SCHED_CODEL_H 3 4 /* 5 * Codel - The Controlled-Delay Active Queue Management algorithm 6 * 7 * Copyright (C) 2011-2012 Kathleen Nichols <nichols@pollere.com> 8 * Copyright (C) 2011-2012 Van Jacobson <van@pollere.net> 9 * Copyright (C) 2012 Michael D. Taht <dave.taht@bufferbloat.net> 10 * Copyright (C) 2012,2015 Eric Dumazet <edumazet@google.com> 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions, and the following disclaimer, 17 * without modification. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. The names of the authors may not be used to endorse or promote products 22 * derived from this software without specific prior written permission. 23 * 24 * Alternatively, provided that this notice is retained in full, this 25 * software may be distributed under the terms of the GNU General 26 * Public License ("GPL") version 2, in which case the provisions of the 27 * GPL apply INSTEAD OF those given above. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 30 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 31 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 32 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 33 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 34 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 35 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 39 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 40 * DAMAGE. 41 * 42 */ 43 44 #include <linux/types.h> 45 #include <linux/ktime.h> 46 #include <linux/skbuff.h> 47 #include <net/pkt_sched.h> 48 #include <net/inet_ecn.h> 49 50 /* Controlling Queue Delay (CoDel) algorithm 51 * ========================================= 52 * Source : Kathleen Nichols and Van Jacobson 53 * http://queue.acm.org/detail.cfm?id=2209336 54 * 55 * Implemented on linux by Dave Taht and Eric Dumazet 56 */ 57 58 59 /* CoDel uses a 1024 nsec clock, encoded in u32 60 * This gives a range of 2199 seconds, because of signed compares 61 */ 62 typedef u32 codel_time_t; 63 typedef s32 codel_tdiff_t; 64 #define CODEL_SHIFT 10 65 #define MS2TIME(a) ((a * NSEC_PER_MSEC) >> CODEL_SHIFT) 66 67 static inline codel_time_t codel_get_time(void) 68 { 69 u64 ns = ktime_get_ns(); 70 71 return ns >> CODEL_SHIFT; 72 } 73 74 /* Dealing with timer wrapping, according to RFC 1982, as desc in wikipedia: 75 * https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution 76 * codel_time_after(a,b) returns true if the time a is after time b. 77 */ 78 #define codel_time_after(a, b) \ 79 (typecheck(codel_time_t, a) && \ 80 typecheck(codel_time_t, b) && \ 81 ((s32)((a) - (b)) > 0)) 82 #define codel_time_before(a, b) codel_time_after(b, a) 83 84 #define codel_time_after_eq(a, b) \ 85 (typecheck(codel_time_t, a) && \ 86 typecheck(codel_time_t, b) && \ 87 ((s32)((a) - (b)) >= 0)) 88 #define codel_time_before_eq(a, b) codel_time_after_eq(b, a) 89 90 static inline u32 codel_time_to_us(codel_time_t val) 91 { 92 u64 valns = ((u64)val << CODEL_SHIFT); 93 94 do_div(valns, NSEC_PER_USEC); 95 return (u32)valns; 96 } 97 98 /** 99 * struct codel_params - contains codel parameters 100 * @target: target queue size (in time units) 101 * @ce_threshold: threshold for marking packets with ECN CE 102 * @interval: width of moving time window 103 * @mtu: device mtu, or minimal queue backlog in bytes. 104 * @ecn: is Explicit Congestion Notification enabled 105 * @ce_threshold_selector: apply ce_threshold to packets matching this value 106 * in the diffserv/ECN byte of the IP header 107 * @ce_threshold_mask: mask to apply to ce_threshold_selector comparison 108 */ 109 struct codel_params { 110 codel_time_t target; 111 codel_time_t ce_threshold; 112 codel_time_t interval; 113 u32 mtu; 114 bool ecn; 115 u8 ce_threshold_selector; 116 u8 ce_threshold_mask; 117 }; 118 119 /** 120 * struct codel_vars - contains codel variables 121 * @count: how many drops we've done since the last time we 122 * entered dropping state 123 * @lastcount: count at entry to dropping state 124 * @dropping: set to true if in dropping state 125 * @rec_inv_sqrt: reciprocal value of sqrt(count) >> 1 126 * @first_above_time: when we went (or will go) continuously above target 127 * for interval 128 * @drop_next: time to drop next packet, or when we dropped last 129 * @ldelay: sojourn time of last dequeued packet 130 */ 131 struct codel_vars { 132 u32 count; 133 u32 lastcount; 134 bool dropping; 135 u16 rec_inv_sqrt; 136 codel_time_t first_above_time; 137 codel_time_t drop_next; 138 codel_time_t ldelay; 139 }; 140 141 #define REC_INV_SQRT_BITS (8 * sizeof(u16)) /* or sizeof_in_bits(rec_inv_sqrt) */ 142 /* needed shift to get a Q0.32 number from rec_inv_sqrt */ 143 #define REC_INV_SQRT_SHIFT (32 - REC_INV_SQRT_BITS) 144 145 /** 146 * struct codel_stats - contains codel shared variables and stats 147 * @maxpacket: largest packet we've seen so far 148 * @drop_count: temp count of dropped packets in dequeue() 149 * @drop_len: bytes of dropped packets in dequeue() 150 * ecn_mark: number of packets we ECN marked instead of dropping 151 * ce_mark: number of packets CE marked because sojourn time was above ce_threshold 152 */ 153 struct codel_stats { 154 u32 maxpacket; 155 u32 drop_count; 156 u32 drop_len; 157 u32 ecn_mark; 158 u32 ce_mark; 159 }; 160 161 #define CODEL_DISABLED_THRESHOLD INT_MAX 162 163 typedef u32 (*codel_skb_len_t)(const struct sk_buff *skb); 164 typedef codel_time_t (*codel_skb_time_t)(const struct sk_buff *skb); 165 typedef void (*codel_skb_drop_t)(struct sk_buff *skb, void *ctx); 166 typedef struct sk_buff * (*codel_skb_dequeue_t)(struct codel_vars *vars, 167 void *ctx); 168 169 #endif 170