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 */ 62typedef u32 codel_time_t; 63typedef s32 codel_tdiff_t; 64#define CODEL_SHIFT 10 65#define MS2TIME(a) ((a * NSEC_PER_MSEC) >> CODEL_SHIFT) 66 67static 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 90static 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 */ 106struct codel_params { 107 codel_time_t target; 108 codel_time_t ce_threshold; 109 codel_time_t interval; 110 u32 mtu; 111 bool ecn; 112}; 113 114/** 115 * struct codel_vars - contains codel variables 116 * @count: how many drops we've done since the last time we 117 * entered dropping state 118 * @lastcount: count at entry to dropping state 119 * @dropping: set to true if in dropping state 120 * @rec_inv_sqrt: reciprocal value of sqrt(count) >> 1 121 * @first_above_time: when we went (or will go) continuously above target 122 * for interval 123 * @drop_next: time to drop next packet, or when we dropped last 124 * @ldelay: sojourn time of last dequeued packet 125 */ 126struct codel_vars { 127 u32 count; 128 u32 lastcount; 129 bool dropping; 130 u16 rec_inv_sqrt; 131 codel_time_t first_above_time; 132 codel_time_t drop_next; 133 codel_time_t ldelay; 134}; 135 136#define REC_INV_SQRT_BITS (8 * sizeof(u16)) /* or sizeof_in_bits(rec_inv_sqrt) */ 137/* needed shift to get a Q0.32 number from rec_inv_sqrt */ 138#define REC_INV_SQRT_SHIFT (32 - REC_INV_SQRT_BITS) 139 140/** 141 * struct codel_stats - contains codel shared variables and stats 142 * @maxpacket: largest packet we've seen so far 143 * @drop_count: temp count of dropped packets in dequeue() 144 * @drop_len: bytes of dropped packets in dequeue() 145 * ecn_mark: number of packets we ECN marked instead of dropping 146 * ce_mark: number of packets CE marked because sojourn time was above ce_threshold 147 */ 148struct codel_stats { 149 u32 maxpacket; 150 u32 drop_count; 151 u32 drop_len; 152 u32 ecn_mark; 153 u32 ce_mark; 154}; 155 156#define CODEL_DISABLED_THRESHOLD INT_MAX 157 158typedef u32 (*codel_skb_len_t)(const struct sk_buff *skb); 159typedef codel_time_t (*codel_skb_time_t)(const struct sk_buff *skb); 160typedef void (*codel_skb_drop_t)(struct sk_buff *skb, void *ctx); 161typedef struct sk_buff * (*codel_skb_dequeue_t)(struct codel_vars *vars, 162 void *ctx); 163 164#endif 165