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 48 /* Controlling Queue Delay (CoDel) algorithm 49 * ========================================= 50 * Source : Kathleen Nichols and Van Jacobson 51 * http://queue.acm.org/detail.cfm?id=2209336 52 * 53 * Implemented on linux by Dave Taht and Eric Dumazet 54 */ 55 56 57 /* CoDel uses a 1024 nsec clock, encoded in u32 58 * This gives a range of 2199 seconds, because of signed compares 59 */ 60 typedef u32 codel_time_t; 61 typedef s32 codel_tdiff_t; 62 #define CODEL_SHIFT 10 63 #define MS2TIME(a) ((a * NSEC_PER_MSEC) >> CODEL_SHIFT) 64 65 static inline codel_time_t codel_get_time(void) 66 { 67 u64 ns = ktime_get_ns(); 68 69 return ns >> CODEL_SHIFT; 70 } 71 72 /* Dealing with timer wrapping, according to RFC 1982, as desc in wikipedia: 73 * https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution 74 * codel_time_after(a,b) returns true if the time a is after time b. 75 */ 76 #define codel_time_after(a, b) \ 77 (typecheck(codel_time_t, a) && \ 78 typecheck(codel_time_t, b) && \ 79 ((s32)((a) - (b)) > 0)) 80 #define codel_time_before(a, b) codel_time_after(b, a) 81 82 #define codel_time_after_eq(a, b) \ 83 (typecheck(codel_time_t, a) && \ 84 typecheck(codel_time_t, b) && \ 85 ((s32)((a) - (b)) >= 0)) 86 #define codel_time_before_eq(a, b) codel_time_after_eq(b, a) 87 88 static inline u32 codel_time_to_us(codel_time_t val) 89 { 90 u64 valns = ((u64)val << CODEL_SHIFT); 91 92 do_div(valns, NSEC_PER_USEC); 93 return (u32)valns; 94 } 95 96 /** 97 * struct codel_params - contains codel parameters 98 * @target: target queue size (in time units) 99 * @ce_threshold: threshold for marking packets with ECN CE 100 * @interval: width of moving time window 101 * @mtu: device mtu, or minimal queue backlog in bytes. 102 * @ecn: is Explicit Congestion Notification enabled 103 * @ce_threshold_selector: apply ce_threshold to packets matching this value 104 * in the diffserv/ECN byte of the IP header 105 * @ce_threshold_mask: mask to apply to ce_threshold_selector comparison 106 */ 107 struct codel_params { 108 codel_time_t target; 109 codel_time_t ce_threshold; 110 codel_time_t interval; 111 u32 mtu; 112 bool ecn; 113 u8 ce_threshold_selector; 114 u8 ce_threshold_mask; 115 }; 116 117 /** 118 * struct codel_vars - contains codel variables 119 * @count: how many drops we've done since the last time we 120 * entered dropping state 121 * @lastcount: count at entry to dropping state 122 * @dropping: set to true if in dropping state 123 * @rec_inv_sqrt: reciprocal value of sqrt(count) >> 1 124 * @first_above_time: when we went (or will go) continuously above target 125 * for interval 126 * @drop_next: time to drop next packet, or when we dropped last 127 * @ldelay: sojourn time of last dequeued packet 128 */ 129 struct codel_vars { 130 u32 count; 131 u32 lastcount; 132 bool dropping; 133 u16 rec_inv_sqrt; 134 codel_time_t first_above_time; 135 codel_time_t drop_next; 136 codel_time_t ldelay; 137 }; 138 139 #define REC_INV_SQRT_BITS (8 * sizeof(u16)) /* or sizeof_in_bits(rec_inv_sqrt) */ 140 /* needed shift to get a Q0.32 number from rec_inv_sqrt */ 141 #define REC_INV_SQRT_SHIFT (32 - REC_INV_SQRT_BITS) 142 143 /** 144 * struct codel_stats - contains codel shared variables and stats 145 * @maxpacket: largest packet we've seen so far 146 * @drop_count: temp count of dropped packets in dequeue() 147 * @drop_len: bytes of dropped packets in dequeue() 148 * @ecn_mark: number of packets we ECN marked instead of dropping 149 * @ce_mark: number of packets CE marked because sojourn time was above ce_threshold 150 */ 151 struct codel_stats { 152 u32 maxpacket; 153 u32 drop_count; 154 u32 drop_len; 155 u32 ecn_mark; 156 u32 ce_mark; 157 }; 158 159 #define CODEL_DISABLED_THRESHOLD INT_MAX 160 161 typedef u32 (*codel_skb_len_t)(const struct sk_buff *skb); 162 typedef codel_time_t (*codel_skb_time_t)(const struct sk_buff *skb); 163 typedef void (*codel_skb_drop_t)(struct sk_buff *skb, void *ctx); 164 typedef struct sk_buff * (*codel_skb_dequeue_t)(struct codel_vars *vars, 165 void *ctx); 166 167 #endif 168