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Diffstat (limited to 'include/net/codel.h')
| -rw-r--r-- | include/net/codel.h | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/include/net/codel.h b/include/net/codel.h new file mode 100644 index 000000000..5fed2f16c --- /dev/null +++ b/include/net/codel.h @@ -0,0 +1,167 @@ +#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 |