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![David S. Miller](/assets/img/avatar_default.png)
Four minor merge conflicts: 1) qca_spi.c renamed the local variable used for the SPI device from spi_device to spi, meanwhile the spi_set_drvdata() call got moved further up in the probe function. 2) Two changes were both adding new members to codel params structure, and thus we had overlapping changes to the initializer function. 3) 'net' was making a fix to sk_release_kernel() which is completely removed in 'net-next'. 4) In net_namespace.c, the rtnl_net_fill() call for GET operations had the command value fixed, meanwhile 'net-next' adjusted the argument signature a bit. This also matches example merge resolutions posted by Stephen Rothwell over the past two days. Signed-off-by: David S. Miller <davem@davemloft.net>
369 lines
11 KiB
C
369 lines
11 KiB
C
#ifndef __NET_SCHED_CODEL_H
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#define __NET_SCHED_CODEL_H
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/*
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* Codel - The Controlled-Delay Active Queue Management algorithm
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*
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* Copyright (C) 2011-2012 Kathleen Nichols <nichols@pollere.com>
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* Copyright (C) 2011-2012 Van Jacobson <van@pollere.net>
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* Copyright (C) 2012 Michael D. Taht <dave.taht@bufferbloat.net>
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* Copyright (C) 2012,2015 Eric Dumazet <edumazet@google.com>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions, and the following disclaimer,
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* without modification.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The names of the authors may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* Alternatively, provided that this notice is retained in full, this
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* software may be distributed under the terms of the GNU General
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* Public License ("GPL") version 2, in which case the provisions of the
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* GPL apply INSTEAD OF those given above.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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*/
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#include <linux/types.h>
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#include <linux/ktime.h>
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#include <linux/skbuff.h>
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#include <net/pkt_sched.h>
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#include <net/inet_ecn.h>
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/* Controlling Queue Delay (CoDel) algorithm
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* =========================================
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* Source : Kathleen Nichols and Van Jacobson
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* http://queue.acm.org/detail.cfm?id=2209336
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*
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* Implemented on linux by Dave Taht and Eric Dumazet
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*/
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/* CoDel uses a 1024 nsec clock, encoded in u32
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* This gives a range of 2199 seconds, because of signed compares
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*/
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typedef u32 codel_time_t;
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typedef s32 codel_tdiff_t;
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#define CODEL_SHIFT 10
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#define MS2TIME(a) ((a * NSEC_PER_MSEC) >> CODEL_SHIFT)
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static inline codel_time_t codel_get_time(void)
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{
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u64 ns = ktime_get_ns();
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return ns >> CODEL_SHIFT;
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}
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/* Dealing with timer wrapping, according to RFC 1982, as desc in wikipedia:
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* https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution
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* codel_time_after(a,b) returns true if the time a is after time b.
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*/
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#define codel_time_after(a, b) \
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(typecheck(codel_time_t, a) && \
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typecheck(codel_time_t, b) && \
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((s32)((a) - (b)) > 0))
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#define codel_time_before(a, b) codel_time_after(b, a)
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#define codel_time_after_eq(a, b) \
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(typecheck(codel_time_t, a) && \
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typecheck(codel_time_t, b) && \
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((s32)((a) - (b)) >= 0))
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#define codel_time_before_eq(a, b) codel_time_after_eq(b, a)
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/* Qdiscs using codel plugin must use codel_skb_cb in their own cb[] */
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struct codel_skb_cb {
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codel_time_t enqueue_time;
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};
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static struct codel_skb_cb *get_codel_cb(const struct sk_buff *skb)
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{
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qdisc_cb_private_validate(skb, sizeof(struct codel_skb_cb));
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return (struct codel_skb_cb *)qdisc_skb_cb(skb)->data;
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}
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static codel_time_t codel_get_enqueue_time(const struct sk_buff *skb)
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{
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return get_codel_cb(skb)->enqueue_time;
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}
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static void codel_set_enqueue_time(struct sk_buff *skb)
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{
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get_codel_cb(skb)->enqueue_time = codel_get_time();
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}
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static inline u32 codel_time_to_us(codel_time_t val)
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{
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u64 valns = ((u64)val << CODEL_SHIFT);
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do_div(valns, NSEC_PER_USEC);
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return (u32)valns;
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}
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/**
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* struct codel_params - contains codel parameters
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* @target: target queue size (in time units)
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* @ce_threshold: threshold for marking packets with ECN CE
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* @interval: width of moving time window
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* @mtu: device mtu, or minimal queue backlog in bytes.
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* @ecn: is Explicit Congestion Notification enabled
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*/
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struct codel_params {
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codel_time_t target;
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codel_time_t ce_threshold;
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codel_time_t interval;
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u32 mtu;
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bool ecn;
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};
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/**
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* struct codel_vars - contains codel variables
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* @count: how many drops we've done since the last time we
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* entered dropping state
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* @lastcount: count at entry to dropping state
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* @dropping: set to true if in dropping state
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* @rec_inv_sqrt: reciprocal value of sqrt(count) >> 1
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* @first_above_time: when we went (or will go) continuously above target
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* for interval
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* @drop_next: time to drop next packet, or when we dropped last
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* @ldelay: sojourn time of last dequeued packet
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*/
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struct codel_vars {
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u32 count;
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u32 lastcount;
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bool dropping;
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u16 rec_inv_sqrt;
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codel_time_t first_above_time;
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codel_time_t drop_next;
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codel_time_t ldelay;
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};
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#define REC_INV_SQRT_BITS (8 * sizeof(u16)) /* or sizeof_in_bits(rec_inv_sqrt) */
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/* needed shift to get a Q0.32 number from rec_inv_sqrt */
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#define REC_INV_SQRT_SHIFT (32 - REC_INV_SQRT_BITS)
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/**
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* struct codel_stats - contains codel shared variables and stats
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* @maxpacket: largest packet we've seen so far
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* @drop_count: temp count of dropped packets in dequeue()
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* ecn_mark: number of packets we ECN marked instead of dropping
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* ce_mark: number of packets CE marked because sojourn time was above ce_threshold
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*/
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struct codel_stats {
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u32 maxpacket;
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u32 drop_count;
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u32 ecn_mark;
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u32 ce_mark;
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};
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#define CODEL_DISABLED_THRESHOLD INT_MAX
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static void codel_params_init(struct codel_params *params,
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const struct Qdisc *sch)
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{
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params->interval = MS2TIME(100);
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params->target = MS2TIME(5);
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params->mtu = psched_mtu(qdisc_dev(sch));
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params->ce_threshold = CODEL_DISABLED_THRESHOLD;
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params->ecn = false;
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}
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static void codel_vars_init(struct codel_vars *vars)
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{
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memset(vars, 0, sizeof(*vars));
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}
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static void codel_stats_init(struct codel_stats *stats)
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{
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stats->maxpacket = 0;
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}
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/*
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* http://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Iterative_methods_for_reciprocal_square_roots
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* new_invsqrt = (invsqrt / 2) * (3 - count * invsqrt^2)
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*
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* Here, invsqrt is a fixed point number (< 1.0), 32bit mantissa, aka Q0.32
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*/
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static void codel_Newton_step(struct codel_vars *vars)
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{
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u32 invsqrt = ((u32)vars->rec_inv_sqrt) << REC_INV_SQRT_SHIFT;
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u32 invsqrt2 = ((u64)invsqrt * invsqrt) >> 32;
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u64 val = (3LL << 32) - ((u64)vars->count * invsqrt2);
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val >>= 2; /* avoid overflow in following multiply */
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val = (val * invsqrt) >> (32 - 2 + 1);
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vars->rec_inv_sqrt = val >> REC_INV_SQRT_SHIFT;
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}
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/*
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* CoDel control_law is t + interval/sqrt(count)
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* We maintain in rec_inv_sqrt the reciprocal value of sqrt(count) to avoid
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* both sqrt() and divide operation.
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*/
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static codel_time_t codel_control_law(codel_time_t t,
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codel_time_t interval,
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u32 rec_inv_sqrt)
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{
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return t + reciprocal_scale(interval, rec_inv_sqrt << REC_INV_SQRT_SHIFT);
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}
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static bool codel_should_drop(const struct sk_buff *skb,
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struct Qdisc *sch,
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struct codel_vars *vars,
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struct codel_params *params,
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struct codel_stats *stats,
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codel_time_t now)
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{
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bool ok_to_drop;
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if (!skb) {
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vars->first_above_time = 0;
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return false;
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}
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vars->ldelay = now - codel_get_enqueue_time(skb);
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sch->qstats.backlog -= qdisc_pkt_len(skb);
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if (unlikely(qdisc_pkt_len(skb) > stats->maxpacket))
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stats->maxpacket = qdisc_pkt_len(skb);
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if (codel_time_before(vars->ldelay, params->target) ||
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sch->qstats.backlog <= params->mtu) {
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/* went below - stay below for at least interval */
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vars->first_above_time = 0;
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return false;
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}
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ok_to_drop = false;
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if (vars->first_above_time == 0) {
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/* just went above from below. If we stay above
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* for at least interval we'll say it's ok to drop
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*/
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vars->first_above_time = now + params->interval;
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} else if (codel_time_after(now, vars->first_above_time)) {
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ok_to_drop = true;
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}
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return ok_to_drop;
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}
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typedef struct sk_buff * (*codel_skb_dequeue_t)(struct codel_vars *vars,
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struct Qdisc *sch);
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static struct sk_buff *codel_dequeue(struct Qdisc *sch,
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struct codel_params *params,
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struct codel_vars *vars,
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struct codel_stats *stats,
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codel_skb_dequeue_t dequeue_func)
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{
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struct sk_buff *skb = dequeue_func(vars, sch);
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codel_time_t now;
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bool drop;
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if (!skb) {
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vars->dropping = false;
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return skb;
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}
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now = codel_get_time();
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drop = codel_should_drop(skb, sch, vars, params, stats, now);
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if (vars->dropping) {
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if (!drop) {
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/* sojourn time below target - leave dropping state */
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vars->dropping = false;
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} else if (codel_time_after_eq(now, vars->drop_next)) {
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/* It's time for the next drop. Drop the current
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* packet and dequeue the next. The dequeue might
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* take us out of dropping state.
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* If not, schedule the next drop.
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* A large backlog might result in drop rates so high
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* that the next drop should happen now,
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* hence the while loop.
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*/
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while (vars->dropping &&
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codel_time_after_eq(now, vars->drop_next)) {
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vars->count++; /* dont care of possible wrap
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* since there is no more divide
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*/
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codel_Newton_step(vars);
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if (params->ecn && INET_ECN_set_ce(skb)) {
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stats->ecn_mark++;
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vars->drop_next =
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codel_control_law(vars->drop_next,
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params->interval,
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vars->rec_inv_sqrt);
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goto end;
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}
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qdisc_drop(skb, sch);
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stats->drop_count++;
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skb = dequeue_func(vars, sch);
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if (!codel_should_drop(skb, sch,
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vars, params, stats, now)) {
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/* leave dropping state */
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vars->dropping = false;
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} else {
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/* and schedule the next drop */
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vars->drop_next =
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codel_control_law(vars->drop_next,
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params->interval,
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vars->rec_inv_sqrt);
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}
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}
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}
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} else if (drop) {
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u32 delta;
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if (params->ecn && INET_ECN_set_ce(skb)) {
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stats->ecn_mark++;
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} else {
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qdisc_drop(skb, sch);
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stats->drop_count++;
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skb = dequeue_func(vars, sch);
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drop = codel_should_drop(skb, sch, vars, params,
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stats, now);
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}
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vars->dropping = true;
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/* if min went above target close to when we last went below it
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* assume that the drop rate that controlled the queue on the
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* last cycle is a good starting point to control it now.
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*/
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delta = vars->count - vars->lastcount;
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if (delta > 1 &&
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codel_time_before(now - vars->drop_next,
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16 * params->interval)) {
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vars->count = delta;
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/* we dont care if rec_inv_sqrt approximation
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* is not very precise :
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* Next Newton steps will correct it quadratically.
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*/
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codel_Newton_step(vars);
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} else {
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vars->count = 1;
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vars->rec_inv_sqrt = ~0U >> REC_INV_SQRT_SHIFT;
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}
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vars->lastcount = vars->count;
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vars->drop_next = codel_control_law(now, params->interval,
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vars->rec_inv_sqrt);
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}
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end:
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if (skb && codel_time_after(vars->ldelay, params->ce_threshold) &&
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INET_ECN_set_ce(skb))
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stats->ce_mark++;
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return skb;
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}
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#endif
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