#ifndef __NET_SCHED_CODEL_H #define __NET_SCHED_CODEL_H /* * Codel - The Controlled-Delay Active Queue Management algorithm * * Copyright (C) 2011-2012 Kathleen Nichols <nichols@pollere.com> * Copyright (C) 2011-2012 Van Jacobson <van@pollere.net> * Copyright (C) 2012 Michael D. Taht <dave.taht@bufferbloat.net> * Copyright (C) 2012,2015 Eric Dumazet <edumazet@google.com> * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions, and the following disclaimer, * without modification. * 2. 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. * 3. The names of the authors may not be used to endorse or promote products * derived from this software without specific prior written permission. * * Alternatively, provided that this notice is retained in full, this * software may be distributed under the terms of the GNU General * Public License ("GPL") version 2, in which case the provisions of the * GPL apply INSTEAD OF those given above. * * 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 <linux/types.h> #include <linux/ktime.h> #include <linux/skbuff.h> /* Controlling Queue Delay (CoDel) algorithm * ========================================= * Source : Kathleen Nichols and Van Jacobson * http://queue.acm.org/detail.cfm?id=2209336 * * Implemented on linux by Dave Taht and Eric Dumazet */ /* CoDel uses a 1024 nsec clock, encoded in u32 * This gives a range of 2199 seconds, because of signed compares */ typedef u32 codel_time_t; typedef s32 codel_tdiff_t; #define CODEL_SHIFT 10 #define MS2TIME(a) ((a * NSEC_PER_MSEC) >> CODEL_SHIFT) static inline codel_time_t codel_get_time(void) { u64 ns = ktime_get_ns(); return ns >> CODEL_SHIFT; } /* Dealing with timer wrapping, according to RFC 1982, as desc in wikipedia: * https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution * codel_time_after(a,b) returns true if the time a is after time b. */ #define codel_time_after(a, b) \ (typecheck(codel_time_t, a) && \ typecheck(codel_time_t, b) && \ ((s32)((a) - (b)) > 0)) #define codel_time_before(a, b) codel_time_after(b, a) #define codel_time_after_eq(a, b) \ (typecheck(codel_time_t, a) && \ typecheck(codel_time_t, b) && \ ((s32)((a) - (b)) >= 0)) #define codel_time_before_eq(a, b) codel_time_after_eq(b, a) static inline u32 codel_time_to_us(codel_time_t val) { u64 valns = ((u64)val << CODEL_SHIFT); do_div(valns, NSEC_PER_USEC); return (u32)valns; } /** * struct codel_params - contains codel parameters * @target: target queue size (in time units) * @ce_threshold: threshold for marking packets with ECN CE * @interval: width of moving time window * @mtu: device mtu, or minimal queue backlog in bytes. * @ecn: is Explicit Congestion Notification enabled * @ce_threshold_selector: apply ce_threshold to packets matching this value * in the diffserv/ECN byte of the IP header * @ce_threshold_mask: mask to apply to ce_threshold_selector comparison */ struct codel_params { codel_time_t target; codel_time_t ce_threshold; codel_time_t interval; u32 mtu; bool ecn; u8 ce_threshold_selector; u8 ce_threshold_mask; }; /** * struct codel_vars - contains codel variables * @count: how many drops we've done since the last time we * entered dropping state * @lastcount: count at entry to dropping state * @dropping: set to true if in dropping state * @rec_inv_sqrt: reciprocal value of sqrt(count) >> 1 * @first_above_time: when we went (or will go) continuously above target * for interval * @drop_next: time to drop next packet, or when we dropped last * @ldelay: sojourn time of last dequeued packet */ struct codel_vars { u32 count; u32 lastcount; bool dropping; u16 rec_inv_sqrt; codel_time_t first_above_time; codel_time_t drop_next; codel_time_t ldelay; }; #define REC_INV_SQRT_BITS (8 * sizeof(u16)) /* or sizeof_in_bits(rec_inv_sqrt) */ /* needed shift to get a Q0.32 number from rec_inv_sqrt */ #define REC_INV_SQRT_SHIFT (32 - REC_INV_SQRT_BITS) /** * struct codel_stats - contains codel shared variables and stats * @maxpacket: largest packet we've seen so far * @drop_count: temp count of dropped packets in dequeue() * @drop_len: bytes of dropped packets in dequeue() * @ecn_mark: number of packets we ECN marked instead of dropping * @ce_mark: number of packets CE marked because sojourn time was above ce_threshold */ struct codel_stats { u32 maxpacket; u32 drop_count; u32 drop_len; u32 ecn_mark; u32 ce_mark; }; #define CODEL_DISABLED_THRESHOLD INT_MAX typedef u32 (*codel_skb_len_t)(const struct sk_buff *skb); typedef codel_time_t (*codel_skb_time_t)(const struct sk_buff *skb); typedef void (*codel_skb_drop_t)(struct sk_buff *skb, void *ctx); typedef struct sk_buff * (*codel_skb_dequeue_t)(struct codel_vars *vars, void *ctx); #endif
