[Cake] [PATCH 2/3] Add Common Applications Kept Enhanced (sch_cake) qdisc
Dave Taht
dave at taht.net
Tue Nov 21 19:55:56 EST 2017
And now I can comment.
I've added this version to a for_upstream branch in the hope that future
commits can be kept in sync.
Is there anything more that should be added to the commit message?
Should I be less snarky?
Dave Taht <dave.taht at gmail.com> writes:
> sch_cake is intended to squeeze the most bandwidth and lowest latency out
> of even the slowest ISP links and routers, while presenting an API simple
> enough that even an ISP can configure it.
>
> Example of use on an ISP uplink:
>
> tc qdisc add dev eth0 cake bandwidth 20Mbit nat docsis ack-filter
>
> Cake can also be used in unlimited mode to drive packets at the speed
> of the underlying link.
>
> Cake is filled with:
>
> * A hybrid Codel/Blue AQM algorithm, “Cobalt”, tied to an FQ_Codel
> derived Flow Queuing system, which autoconfigures based on the bandwidth.
> * A unique "triple-isolate" mode (the default) which balances per-flow
> and per-host flow FQ even through NAT.
> * An integral deficit based shaper with extensive dsl and docsis support
> that can also be used in unlimited mode.
> * 8 way set associative queuing to reduce flow collisions to a minimum.
> * A reasonable interpretation of various diffserv latency/loss tradeoffs.
> * Support for washing diffserv for entering and exiting traffic.
> * Perfect support for interacting with Docsis 3.0 shapers.
> * Extensive support for DSL framing types.
> * (New) Support for ack filtering.
> - 20 % better throughput at a 16x1 down/up ratio on the rrul test.
> * Extensive statistics for measuring, loss, ecn markings, latency variation.
>
> There are some features still considered experimental, notably the
> ingress_autorate bandwidth estimator and cobalt itself.
>
> Various versions shipping have been available as an out of tree build for
> kernel versions going back to 3.10, as the embedded router world has been
> running a few years behind mainline Linux. A stable version has been
> generally available on lede-17.01 and later.
>
> sch_cake replaces a combination of iptables, tc filter, htb and fq_codel in
> the sqm-scripts, with sane defaults and vastly easier configuration.
>
> Cake's principal author is Jonathan Morton, with contributions from
> Kevin Darbyshire-Bryant, Toke Høiland-Jørgensen, Sebastian Moeller,
> Ryan Mounce, Dean Scarff, Guido Sarducci, Nils Andreas Svee, Dave Täht, and
> Loganaden Velvindron.
> ---
> include/net/cobalt.h | 152 +++
> net/sched/sch_cake.c | 2551 ++++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 2703 insertions(+)
> create mode 100644 include/net/cobalt.h
> create mode 100644 net/sched/sch_cake.c
>
> diff --git a/include/net/cobalt.h b/include/net/cobalt.h
> new file mode 100644
> index 0000000..0d1e794
> --- /dev/null
> +++ b/include/net/cobalt.h
> @@ -0,0 +1,152 @@
> +#ifndef __NET_SCHED_COBALT_H
> +#define __NET_SCHED_COBALT_H
> +
> +/* COBALT - Codel-BLUE Alternate AQM algorithm.
> + *
> + * Copyright (C) 2011-2012 Kathleen Nichols <nichols at pollere.com>
> + * Copyright (C) 2011-2012 Van Jacobson <van at pollere.net>
> + * Copyright (C) 2012 Eric Dumazet <edumazet at google.com>
> + * Copyright (C) 2016-2017 Michael D. Täht <dave.taht at gmail.com>
> + * Copyright (c) 2015-2017 Jonathan Morton <chromatix99 at gmail.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.
> + */
> +
> +/* COBALT operates the Codel and BLUE algorithms in parallel, in order to
> + * obtain the best features of each. Codel is excellent on flows which
> + * respond to congestion signals in a TCP-like way. BLUE is more effective on
> + * unresponsive flows.
> + */
> +
> +#include <linux/version.h>
> +#include <linux/types.h>
> +#include <linux/ktime.h>
> +#include <linux/skbuff.h>
> +#include <net/pkt_sched.h>
> +#include <net/inet_ecn.h>
> +#include <linux/reciprocal_div.h>
> +
> +typedef u64 cobalt_time_t;
> +typedef s64 cobalt_tdiff_t;
> +
> +#define MS2TIME(a) (a * (u64) NSEC_PER_MSEC)
> +#define US2TIME(a) (a * (u64) NSEC_PER_USEC)
> +
> +struct cobalt_skb_cb {
> + cobalt_time_t enqueue_time;
> +};
> +
> +static inline cobalt_time_t cobalt_get_time(void)
> +{
> + return ktime_get_ns();
> +}
I don't see these typedefs as necessarily helpful in understanding
the code, just using ktime_get_ns might be saner. Can live with it.
> +struct cake_flow {
> + /* this stuff is all needed per-flow at dequeue time */
> + struct sk_buff *head;
> + struct sk_buff *tail;
> + struct sk_buff *ackcheck;
> + struct list_head flowchain;
> + s32 deficit;
> + struct cobalt_vars cvars;
> + u16 srchost; /* index into cake_host table */
> + u16 dsthost;
> + u8 set;
> +}; /* please try to keep this structure <= 64 bytes */
It isn't. Can just kill the comment.
> +
> +struct cake_host {
> + u32 srchost_tag;
> + u32 dsthost_tag;
> + u16 srchost_refcnt;
> + u16 dsthost_refcnt;
> +};
> +
> +struct cake_heap_entry {
> + u16 t:3, b:10;
> +};
> +
> +struct cake_tin_data {
> + struct cake_flow flows[CAKE_QUEUES];
> + u32 backlogs[CAKE_QUEUES];
> + u32 tags[CAKE_QUEUES]; /* for set association */
> + u16 overflow_idx[CAKE_QUEUES];
> + struct cake_host hosts[CAKE_QUEUES]; /* for triple isolation */
> + u32 perturbation;
> + u16 flow_quantum;
> +
> + struct cobalt_params cparams;
> + u32 drop_overlimit;
> + u16 bulk_flow_count;
> + u16 sparse_flow_count;
> + u16 decaying_flow_count;
> + u16 unresponsive_flow_count;
> +
> + u16 max_skblen;
> +
> + struct list_head new_flows;
> + struct list_head old_flows;
> + struct list_head decaying_flows;
> +
> + /* time_next = time_this + ((len * rate_ns) >> rate_shft) */
> + u64 tin_time_next_packet;
> + u32 tin_rate_ns;
> + u32 tin_rate_bps;
> + u16 tin_rate_shft;
> +
> + u16 tin_quantum_prio;
> + u16 tin_quantum_band;
> + s32 tin_deficit;
> + u32 tin_backlog;
> + u32 tin_dropped;
> + u32 tin_ecn_mark;
> +
> + u32 packets;
> + u64 bytes;
> +
> + u32 ack_drops;
> +
> + /* moving averages */
> + cobalt_time_t avge_delay;
> + cobalt_time_t peak_delay;
> + cobalt_time_t base_delay;
> +
> + /* hash function stats */
> + u32 way_directs;
> + u32 way_hits;
> + u32 way_misses;
> + u32 way_collisions;
> +}; /* number of tins is small, so size of this struct doesn't matter much */
> +
> +struct cake_sched_data {
> + struct cake_tin_data *tins;
> +
> + struct cake_heap_entry overflow_heap[CAKE_QUEUES * CAKE_MAX_TINS];
> + u16 overflow_timeout;
> +
> + u16 tin_cnt;
> + u8 tin_mode;
> + u8 flow_mode;
> +
> + /* time_next = time_this + ((len * rate_ns) >> rate_shft) */
> + u16 rate_shft;
> + u64 time_next_packet;
> + u64 failsafe_next_packet;
> + u32 rate_ns;
> + u32 rate_bps;
> + u16 rate_flags;
> + s16 rate_overhead;
> + u16 rate_mpu;
> + u32 interval;
> + u32 target;
> +
> + /* resource tracking */
> + u32 buffer_used;
> + u32 buffer_max_used;
> + u32 buffer_limit;
> + u32 buffer_config_limit;
> +
> + /* indices for dequeue */
> + u16 cur_tin;
> + u16 cur_flow;
> +
> + struct qdisc_watchdog watchdog;
> + const u8 *tin_index;
> + const u8 *tin_order;
> +
> + /* bandwidth capacity estimate */
> + u64 last_packet_time;
> + u64 avg_packet_interval;
> + u64 avg_window_begin;
> + u32 avg_window_bytes;
> + u32 avg_peak_bandwidth;
> + u64 last_reconfig_time;
> +};
> +
> +enum {
> + CAKE_MODE_BESTEFFORT = 1,
> + CAKE_MODE_PRECEDENCE,
> + CAKE_MODE_DIFFSERV8,
> + CAKE_MODE_DIFFSERV4,
> + CAKE_MODE_LLT,
> + CAKE_MODE_DIFFSERV3,
> + CAKE_MODE_MAX
> +};
> +
> +enum {
> + CAKE_FLAG_ATM = 0x0001,
> + CAKE_FLAG_PTM = 0x0002,
> + CAKE_FLAG_AUTORATE_INGRESS = 0x0010,
> + CAKE_FLAG_INGRESS = 0x0040,
Why the gap?
> + CAKE_FLAG_WASH = 0x0100,
> + CAKE_FLAG_ACK_FILTER = 0x0200,
> + CAKE_FLAG_ACK_AGGRESSIVE = 0x0400
> +};
We could create a #define CAKE_ACK_FILTERS (CAKE_FLAG_ACK_FILTER |\
CAKE_FLAG_ACK_AGGRESSIVE)
> +
> +enum {
> + CAKE_FLOW_NONE = 0,
> + CAKE_FLOW_SRC_IP,
> + CAKE_FLOW_DST_IP,
> + CAKE_FLOW_HOSTS, /* = CAKE_FLOW_SRC_IP | CAKE_FLOW_DST_IP */
> + CAKE_FLOW_FLOWS,
> + CAKE_FLOW_DUAL_SRC, /* = CAKE_FLOW_SRC_IP | CAKE_FLOW_FLOWS */
> + CAKE_FLOW_DUAL_DST, /* = CAKE_FLOW_DST_IP | CAKE_FLOW_FLOWS */
> + CAKE_FLOW_TRIPLE, /* = CAKE_FLOW_HOSTS | CAKE_FLOW_FLOWS */
> + CAKE_FLOW_MAX,
> + CAKE_FLOW_NAT_FLAG = 64
> +};
> +
> +static u16 quantum_div[CAKE_QUEUES + 1] = {0};
> +
> +/* Diffserv lookup tables */
> +
> +static const u8 precedence[] = {0, 0, 0, 0, 0, 0, 0, 0,
> + 1, 1, 1, 1, 1, 1, 1, 1,
> + 2, 2, 2, 2, 2, 2, 2, 2,
> + 3, 3, 3, 3, 3, 3, 3, 3,
> + 4, 4, 4, 4, 4, 4, 4, 4,
> + 5, 5, 5, 5, 5, 5, 5, 5,
> + 6, 6, 6, 6, 6, 6, 6, 6,
> + 7, 7, 7, 7, 7, 7, 7, 7,
> + };
> +
> +static const u8 diffserv_llt[] = {1, 0, 0, 1, 2, 2, 1, 1,
> + 3, 1, 1, 1, 1, 1, 1, 1,
> + 1, 1, 1, 1, 1, 1, 1, 1,
> + 1, 1, 1, 1, 1, 1, 1, 1,
> + 1, 1, 1, 1, 1, 1, 1, 1,
> + 1, 1, 1, 1, 2, 1, 2, 1,
> + 4, 1, 1, 1, 1, 1, 1, 1,
> + 4, 1, 1, 1, 1, 1, 1, 1,
> + };
> +
> +static const u8 diffserv8[] = {2, 5, 1, 2, 4, 2, 2, 2,
> + 0, 2, 1, 2, 1, 2, 1, 2,
> + 5, 2, 4, 2, 4, 2, 4, 2,
> + 3, 2, 3, 2, 3, 2, 3, 2,
> + 6, 2, 3, 2, 3, 2, 3, 2,
> + 6, 2, 2, 2, 6, 2, 6, 2,
> + 7, 2, 2, 2, 2, 2, 2, 2,
> + 7, 2, 2, 2, 2, 2, 2, 2,
> + };
> +
> +static const u8 diffserv4[] = {0, 2, 0, 0, 2, 0, 0, 0,
> + 1, 0, 0, 0, 0, 0, 0, 0,
> + 2, 0, 2, 0, 2, 0, 2, 0,
> + 2, 0, 2, 0, 2, 0, 2, 0,
> + 3, 0, 2, 0, 2, 0, 2, 0,
> + 3, 0, 0, 0, 3, 0, 3, 0,
> + 3, 0, 0, 0, 0, 0, 0, 0,
> + 3, 0, 0, 0, 0, 0, 0, 0,
> + };
> +
> +static const u8 diffserv3[] = {0, 0, 0, 0, 2, 0, 0, 0,
> + 1, 0, 0, 0, 0, 0, 0, 0,
> + 0, 0, 0, 0, 0, 0, 0, 0,
> + 0, 0, 0, 0, 0, 0, 0, 0,
> + 0, 0, 0, 0, 0, 0, 0, 0,
> + 0, 0, 0, 0, 2, 0, 2, 0,
> + 2, 0, 0, 0, 0, 0, 0, 0,
> + 2, 0, 0, 0, 0, 0, 0, 0,
> + };
> +
> +static const u8 besteffort[] = {0, 0, 0, 0, 0, 0, 0, 0,
> + 0, 0, 0, 0, 0, 0, 0, 0,
> + 0, 0, 0, 0, 0, 0, 0, 0,
> + 0, 0, 0, 0, 0, 0, 0, 0,
> + 0, 0, 0, 0, 0, 0, 0, 0,
> + 0, 0, 0, 0, 0, 0, 0, 0,
> + 0, 0, 0, 0, 0, 0, 0, 0,
> + 0, 0, 0, 0, 0, 0, 0, 0,
> + };
> +
> +/* tin priority order for stats dumping */
> +
> +static const u8 normal_order[] = {0, 1, 2, 3, 4, 5, 6, 7};
> +static const u8 bulk_order[] = {1, 0, 2, 3};
> +
> +#define REC_INV_SQRT_CACHE (16)
> +static u32 cobalt_rec_inv_sqrt_cache[REC_INV_SQRT_CACHE] = {0};
> +
> +/* http://en.wikipedia.org/wiki/Methods_of_computing_square_roots
> + * new_invsqrt = (invsqrt / 2) * (3 - count * invsqrt^2)
> + *
> + * Here, invsqrt is a fixed point number (< 1.0), 32bit mantissa, aka Q0.32
> + */
> +
> +static void cobalt_newton_step(struct cobalt_vars *vars)
> +{
> + u32 invsqrt = vars->rec_inv_sqrt;
> + u32 invsqrt2 = ((u64)invsqrt * invsqrt) >> 32;
> + u64 val = (3LL << 32) - ((u64)vars->count * invsqrt2);
> +
> + val >>= 2; /* avoid overflow in following multiply */
> + val = (val * invsqrt) >> (32 - 2 + 1);
> +
> + vars->rec_inv_sqrt = val;
> +}
> +
> +static void cobalt_invsqrt(struct cobalt_vars *vars)
> +{
> + if (vars->count < REC_INV_SQRT_CACHE)
> + vars->rec_inv_sqrt = cobalt_rec_inv_sqrt_cache[vars->count];
> + else
> + cobalt_newton_step(vars);
> +}
> +
> +/* There is a big difference in timing between the accurate values placed in
> + * the cache and the approximations given by a single Newton step for small
> + * count values, particularly when stepping from count 1 to 2 or vice versa.
> + * Above 16, a single Newton step gives sufficient accuracy in either
> + * direction, given the precision stored.
> + *
> + * The magnitude of the error when stepping up to count 2 is such as to give
> + * the value that *should* have been produced at count 4.
> + */
> +
> +static void cobalt_cache_init(void)
> +{
> + struct cobalt_vars v;
> +
> + memset(&v, 0, sizeof(v));
> + v.rec_inv_sqrt = ~0U;
> + cobalt_rec_inv_sqrt_cache[0] = v.rec_inv_sqrt;
> +
> + for (v.count = 1; v.count < REC_INV_SQRT_CACHE; v.count++) {
> + cobalt_newton_step(&v);
> + cobalt_newton_step(&v);
> + cobalt_newton_step(&v);
> + cobalt_newton_step(&v);
> +
> + cobalt_rec_inv_sqrt_cache[v.count] = v.rec_inv_sqrt;
> + }
> +}
> +
> +void cobalt_vars_init(struct cobalt_vars *vars)
> +{
> + memset(vars, 0, sizeof(*vars));
> +
> + if (!cobalt_rec_inv_sqrt_cache[0]) {
> + cobalt_cache_init();
> + cobalt_rec_inv_sqrt_cache[0] = ~0;
> + }
> +}
> +
> +/* CoDel control_law is t + interval/sqrt(count)
> + * We maintain in rec_inv_sqrt the reciprocal value of sqrt(count) to avoid
> + * both sqrt() and divide operation.
> + */
> +static cobalt_time_t cobalt_control_law(cobalt_time_t t,
> + cobalt_time_t interval,
> + u32 rec_inv_sqrt)
> +{
> + return t + reciprocal_scale(interval, rec_inv_sqrt);
> +}
> +
> +/* Call this when a packet had to be dropped due to queue overflow. Returns
> + * true if the BLUE state was quiescent before but active after this call.
> + */
> +bool cobalt_queue_full(struct cobalt_vars *vars, struct cobalt_params *p,
> + cobalt_time_t now)
oops, this should be static.
> +{
> + bool up = false;
> +
> + if ((now - vars->blue_timer) > p->target) {
> + up = !vars->p_drop;
> + vars->p_drop += p->p_inc;
> + if (vars->p_drop < p->p_inc)
> + vars->p_drop = ~0;
> + vars->blue_timer = now;
> + }
> + vars->dropping = true;
> + vars->drop_next = now;
> + if (!vars->count)
> + vars->count = 1;
> +
> + return up;
> +}
> +
> +/* Call this when the queue was serviced but turned out to be empty. Returns
> + * true if the BLUE state was active before but quiescent after this call.
> + */
> +bool cobalt_queue_empty(struct cobalt_vars *vars, struct cobalt_params *p,
> + cobalt_time_t now)
static
> +{
> + bool down = false;
> +
> + if (vars->p_drop && (now - vars->blue_timer) > p->target) {
> + if (vars->p_drop < p->p_dec)
> + vars->p_drop = 0;
> + else
> + vars->p_drop -= p->p_dec;
> + vars->blue_timer = now;
> + down = !vars->p_drop;
> + }
> + vars->dropping = false;
> +
> + if (vars->count && (now - vars->drop_next) >= 0) {
> + vars->count--;
> + cobalt_invsqrt(vars);
> + vars->drop_next = cobalt_control_law(vars->drop_next,
> + p->interval,
> + vars->rec_inv_sqrt);
> + }
> +
> + return down;
> +}
> +
> +/* Call this with a freshly dequeued packet for possible congestion marking.
> + * Returns true as an instruction to drop the packet, false for delivery.
> + */
> +bool cobalt_should_drop(struct cobalt_vars *vars,
> + struct cobalt_params *p,
> + cobalt_time_t now,
> + struct sk_buff *skb)
static
> +{
> + bool drop = false;
> +
> + /* Simplified Codel implementation */
> + cobalt_tdiff_t sojourn = now - cobalt_get_enqueue_time(skb);
> +
> +/* The 'schedule' variable records, in its sign, whether 'now' is before or
> + * after 'drop_next'. This allows 'drop_next' to be updated before the next
> + * scheduling decision is actually branched, without destroying that
> + * information. Similarly, the first 'schedule' value calculated is preserved
> + * in the boolean 'next_due'.
> + *
> + * As for 'drop_next', we take advantage of the fact that 'interval' is both
> + * the delay between first exceeding 'target' and the first signalling event,
> + * *and* the scaling factor for the signalling frequency. It's therefore very
> + * natural to use a single mechanism for both purposes, and eliminates a
> + * significant amount of reference Codel's spaghetti code. To help with this,
> + * both the '0' and '1' entries in the invsqrt cache are 0xFFFFFFFF, as close
> + * as possible to 1.0 in fixed-point.
> + */
> +
> + cobalt_tdiff_t schedule = now - vars->drop_next;
> + bool over_target = sojourn > p->target;
> + bool next_due = vars->count && schedule >= 0;
> +
> + vars->ecn_marked = false;
> +
> + if (over_target) {
> + if (!vars->dropping) {
> + vars->dropping = true;
> + vars->drop_next = cobalt_control_law(now,
> + p->interval,
> + vars->rec_inv_sqrt);
> + }
> + if (!vars->count)
> + vars->count = 1;
> + } else if (vars->dropping) {
> + vars->dropping = false;
> + }
> +
> + if (next_due && vars->dropping) {
> + /* Use ECN mark if possible, otherwise drop */
> + drop = !(vars->ecn_marked = INET_ECN_set_ce(skb));
> +
> + vars->count++;
> + if (!vars->count)
> + vars->count--;
> + cobalt_invsqrt(vars);
> + vars->drop_next = cobalt_control_law(vars->drop_next,
> + p->interval,
> + vars->rec_inv_sqrt);
> + schedule = now - vars->drop_next;
> + } else {
> + while (next_due) {
> + vars->count--;
> + cobalt_invsqrt(vars);
> + vars->drop_next = cobalt_control_law(vars->drop_next,
> + p->interval,
> + vars->rec_inv_sqrt);
> + schedule = now - vars->drop_next;
> + next_due = vars->count && schedule >= 0;
> + }
> + }
> +
> + /* Simple BLUE implementation. Lack of ECN is deliberate. */
> + if (vars->p_drop)
> + drop |= (prandom_u32() < vars->p_drop);
> +
> + /* Overload the drop_next field as an activity timeout */
> + if (!vars->count)
> + vars->drop_next = now + p->interval;
> + else if (schedule > 0 && !drop)
> + vars->drop_next = now;
> +
> + return drop;
> +}
> +
> +#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
Oops, I meant to add IS_ENABLED(NF_CONNTRACK). How far back does that
define go?
> +static inline void cake_update_flowkeys(struct flow_keys *keys,
> + const struct sk_buff *skb)
> +{
> + enum ip_conntrack_info ctinfo;
> + bool rev = false;
> +
> + struct nf_conn *ct;
> + const struct nf_conntrack_tuple *tuple;
> +
> + if (tc_skb_protocol(skb) != htons(ETH_P_IP))
> + return;
> +
> + ct = nf_ct_get(skb, &ctinfo);
> + if (ct) {
> + tuple = nf_ct_tuple(ct, CTINFO2DIR(ctinfo));
> + } else {
> + const struct nf_conntrack_tuple_hash *hash;
> + struct nf_conntrack_tuple srctuple;
> +
> + if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb),
> + NFPROTO_IPV4, dev_net(skb->dev),
> + &srctuple))
> + return;
> +
> + hash = nf_conntrack_find_get(dev_net(skb->dev),
> + &nf_ct_zone_dflt,
> + &srctuple);
> + if (!hash)
> + return;
> +
> + rev = true;
> + ct = nf_ct_tuplehash_to_ctrack(hash);
> + tuple = nf_ct_tuple(ct, !hash->tuple.dst.dir);
> + }
> +
> + keys->addrs.v4addrs.src = rev ? tuple->dst.u3.ip : tuple->src.u3.ip;
> + keys->addrs.v4addrs.dst = rev ? tuple->src.u3.ip : tuple->dst.u3.ip;
> +
> + if (keys->ports.ports) {
> + keys->ports.src = rev ? tuple->dst.u.all : tuple->src.u.all;
> + keys->ports.dst = rev ? tuple->src.u.all : tuple->dst.u.all;
> + }
> +
> + if (rev)
> + nf_ct_put(ct);
> +}
> +#else
> +static inline void cake_update_flowkeys(struct flow_keys *keys,
> + const struct sk_buff *skb)
> +{
> + /* There is nothing we can do here without CONNTRACK */
> +}
> +#endif
> +
> +static inline u32
> +cake_hash(struct cake_tin_data *q, const struct sk_buff *skb, int flow_mode)
> +{
> + struct flow_keys keys, host_keys;
> + u32 flow_hash = 0, srchost_hash, dsthost_hash;
> + u16 reduced_hash, srchost_idx, dsthost_idx;
> +
> + if (unlikely(flow_mode == CAKE_FLOW_NONE))
> + return 0;
> +
> + skb_flow_dissect_flow_keys(skb, &keys,
> + FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL);
> +
> + if (flow_mode & CAKE_FLOW_NAT_FLAG)
> + cake_update_flowkeys(&keys, skb);
> +
> + /* flow_hash_from_keys() sorts the addresses by value, so we have
> + * to preserve their order in a separate data structure to treat
> + * src and dst host addresses as independently selectable.
> + */
> + host_keys = keys;
> + host_keys.ports.ports = 0;
> + host_keys.basic.ip_proto = 0;
> + host_keys.keyid.keyid = 0;
> + host_keys.tags.flow_label = 0;
> +
> + switch (host_keys.control.addr_type) {
> + case FLOW_DISSECTOR_KEY_IPV4_ADDRS:
> + host_keys.addrs.v4addrs.src = 0;
> + dsthost_hash = flow_hash_from_keys(&host_keys);
> + host_keys.addrs.v4addrs.src = keys.addrs.v4addrs.src;
> + host_keys.addrs.v4addrs.dst = 0;
> + srchost_hash = flow_hash_from_keys(&host_keys);
> + break;
> +
> + case FLOW_DISSECTOR_KEY_IPV6_ADDRS:
> + memset(&host_keys.addrs.v6addrs.src, 0,
> + sizeof(host_keys.addrs.v6addrs.src));
> + dsthost_hash = flow_hash_from_keys(&host_keys);
> + host_keys.addrs.v6addrs.src = keys.addrs.v6addrs.src;
> + memset(&host_keys.addrs.v6addrs.dst, 0,
> + sizeof(host_keys.addrs.v6addrs.dst));
> + srchost_hash = flow_hash_from_keys(&host_keys);
> + break;
> +
> + default:
> + dsthost_hash = 0;
> + srchost_hash = 0;
> + };
> +
> + /* This *must* be after the above switch, since as a
> + * side-effect it sorts the src and dst addresses.
> + */
> + if (flow_mode & CAKE_FLOW_FLOWS)
> + flow_hash = flow_hash_from_keys(&keys);
> +
> + if (!(flow_mode & CAKE_FLOW_FLOWS)) {
> + if (flow_mode & CAKE_FLOW_SRC_IP)
> + flow_hash ^= srchost_hash;
> +
> + if (flow_mode & CAKE_FLOW_DST_IP)
> + flow_hash ^= dsthost_hash;
> + }
> +
> + reduced_hash = flow_hash % CAKE_QUEUES;
> + srchost_idx = srchost_hash % CAKE_QUEUES;
> + dsthost_idx = dsthost_hash % CAKE_QUEUES;
> +
> + /* set-associative hashing */
> + /* fast path if no hash collision (direct lookup succeeds) */
> + if (likely(q->tags[reduced_hash] == flow_hash &&
> + q->flows[reduced_hash].set)) {
> + q->way_directs++;
> + } else {
> + u32 inner_hash = reduced_hash % CAKE_SET_WAYS;
> + u32 outer_hash = reduced_hash - inner_hash;
> + u32 i, k;
> + bool need_allocate_src = false;
> + bool need_allocate_dst = false;
> +
> + /* check if any active queue in the set is reserved for
> + * this flow.
> + */
> + for (i = 0, k = inner_hash; i < CAKE_SET_WAYS;
> + i++, k = (k + 1) % CAKE_SET_WAYS) {
> + if (q->tags[outer_hash + k] == flow_hash) {
> + if (i)
> + q->way_hits++;
> +
> + if (!q->flows[outer_hash + k].set) {
> + /* need to increment host refcnts */
> + need_allocate_src = true;
> + need_allocate_dst = true;
> + }
> +
> + goto found;
> + }
> + }
> +
> + /* no queue is reserved for this flow, look for an
> + * empty one.
> + */
> + for (i = 0; i < CAKE_SET_WAYS;
> + i++, k = (k + 1) % CAKE_SET_WAYS) {
> + if (!q->flows[outer_hash + k].set) {
> + q->way_misses++;
> + need_allocate_src = true;
> + need_allocate_dst = true;
> + goto found;
> + }
> + }
> +
> + /* With no empty queues, default to the original
> + * queue, accept the collision, update the host tags.
> + */
> + q->way_collisions++;
> + q->hosts[q->flows[reduced_hash].srchost].srchost_refcnt--;
> + q->hosts[q->flows[reduced_hash].dsthost].dsthost_refcnt--;
> + need_allocate_src = true;
> + need_allocate_dst = true;
> +
> +found:
Not huge on dangling gotos, would rather move them to the below line.
> + /* reserve queue for future packets in same flow */
> + reduced_hash = outer_hash + k;
> + q->tags[reduced_hash] = flow_hash;
> +
> + if (need_allocate_src) {
> + inner_hash = srchost_idx % CAKE_SET_WAYS;
> + outer_hash = srchost_idx - inner_hash;
> + for (i = 0, k = inner_hash; i < CAKE_SET_WAYS;
> + i++, k = (k + 1) % CAKE_SET_WAYS) {
> + if (q->hosts[outer_hash + k].srchost_tag ==
> + srchost_hash)
> + goto found_src;
> + }
> + for (i = 0; i < CAKE_SET_WAYS;
> + i++, k = (k + 1) % CAKE_SET_WAYS) {
> + if (!q->hosts[outer_hash + k].srchost_refcnt)
> + break;
> + }
> + q->hosts[outer_hash + k].srchost_tag = srchost_hash;
> +found_src:
> + srchost_idx = outer_hash + k;
> + q->hosts[srchost_idx].srchost_refcnt++;
> + q->flows[reduced_hash].srchost = srchost_idx;
> + }
> +
> + if (need_allocate_dst) {
> + inner_hash = dsthost_idx % CAKE_SET_WAYS;
> + outer_hash = dsthost_idx - inner_hash;
> + for (i = 0, k = inner_hash; i < CAKE_SET_WAYS;
> + i++, k = (k + 1) % CAKE_SET_WAYS) {
> + if (q->hosts[outer_hash + k].dsthost_tag ==
> + dsthost_hash)
> + goto found_dst;
> + }
> + for (i = 0; i < CAKE_SET_WAYS;
> + i++, k = (k + 1) % CAKE_SET_WAYS) {
> + if (!q->hosts[outer_hash + k].dsthost_refcnt)
> + break;
> + }
> + q->hosts[outer_hash + k].dsthost_tag = dsthost_hash;
> +found_dst:
> + dsthost_idx = outer_hash + k;
> + q->hosts[dsthost_idx].dsthost_refcnt++;
> + q->flows[reduced_hash].dsthost = dsthost_idx;
> + }
> + }
> +
> + return reduced_hash;
> +}
> +
> +/* helper functions : might be changed when/if skb use a standard list_head */
> +/* remove one skb from head of slot queue */
> +
> +static inline struct sk_buff *dequeue_head(struct cake_flow *flow)
> +{
> + struct sk_buff *skb = flow->head;
> +
> + if (skb) {
> + flow->head = skb->next;
> + skb->next = NULL;
> +
> + if (skb == flow->ackcheck)
> + flow->ackcheck = NULL;
Is there a sane way to move this check elsewhere and only when ack
filtering is enabled?
> + }
> +
> + return skb;
> +}
> +
> +/* add skb to flow queue (tail add) */
> +
> +static inline void
> +flow_queue_add(struct cake_flow *flow, struct sk_buff *skb)
> +{
> + if (!flow->head)
> + flow->head = skb;
> + else
> + flow->tail->next = skb;
> + flow->tail = skb;
> + skb->next = NULL;
> +}
> +
> +static struct sk_buff *ack_filter(struct cake_flow *flow, bool aggressive)
> +{
> + int seglen;
> + struct sk_buff *skb = flow->tail, *skb_check, *skb_check_prev;
> + struct iphdr *iph, *iph_check;
> + struct ipv6hdr *ipv6h, *ipv6h_check;
> + struct tcphdr *tcph, *tcph_check;
> +
> + bool otherconn_ack_seen = false;
> + struct sk_buff *otherconn_checked_to = NULL;
> + bool thisconn_redundant_seen = false, thisconn_seen_last = false;
> + struct sk_buff *thisconn_checked_to = NULL, *thisconn_ack = NULL;
> +
> + /* no other possible ACKs to filter */
> + if (flow->head == skb)
> + return NULL;
> +
> + iph = skb->encapsulation ? inner_ip_hdr(skb) : ip_hdr(skb);
> + ipv6h = skb->encapsulation ? inner_ipv6_hdr(skb) : ipv6_hdr(skb);
> +
> + /* check that the innermost network header is v4/v6, and contains TCP */
> + if (iph->version == 4) {
> + if (iph->protocol != IPPROTO_TCP)
> + return NULL;
> + seglen = ntohs(iph->tot_len) - (4 * iph->ihl);
> + tcph = (struct tcphdr *)((void *)iph + (4 * iph->ihl));
> + } else if (ipv6h->version == 6) {
> + if (ipv6h->nexthdr != IPPROTO_TCP)
> + return NULL;
> + seglen = ntohs(ipv6h->payload_len);
> + tcph = (struct tcphdr *)((void *)ipv6h + sizeof(struct ipv6hdr));
> + } else {
> + return NULL;
> + }
> +
> + /* the 'triggering' packet need only have the ACK flag set.
> + * also check that SYN is not set, as there won't be any previous ACKs.
> + */
> + if ((tcp_flag_word(tcph) &
> + cpu_to_be32(0x00120000)) != TCP_FLAG_ACK)
Magic number
> + return NULL;
> +
> + /* the 'triggering' ACK is at the end of the queue,
> + * we have already returned if it is the only packet in the flow.
> + * stop before last packet in queue, don't compare trigger ACK to itself
> + * start where we finished last time if recorded in ->ackcheck
> + * otherwise start from the the head of the flow queue.
> + */
> + skb_check_prev = flow->ackcheck;
> + skb_check = flow->ackcheck ?: flow->head;
> +
> + while (skb_check->next) {
> + bool pure_ack, thisconn;
> +
> + /* don't increment if at head of flow queue (_prev == NULL) */
> + if (skb_check_prev) {
> + skb_check_prev = skb_check;
> + skb_check = skb_check->next;
> + if (!skb_check->next)
> + break;
> + } else {
> + skb_check_prev = ERR_PTR(-1);
> + }
> +
> + iph_check = skb_check->encapsulation ?
> + inner_ip_hdr(skb_check) : ip_hdr(skb_check);
> + ipv6h_check = skb_check->encapsulation ?
> + inner_ipv6_hdr(skb_check) : ipv6_hdr(skb_check);
> +
> + if (iph_check->version == 4) {
> + if (iph_check->protocol != IPPROTO_TCP)
> + continue;
> + seglen = ntohs(iph_check->tot_len) - (4 * iph_check->ihl);
> + tcph_check = (struct tcphdr *)((void *)iph_check
> + + (4 * iph_check->ihl));
> + if (iph->version == 4 &&
> + iph_check->saddr == iph->saddr &&
> + iph_check->daddr == iph->daddr) {
> + thisconn = true;
> + } else {
> + thisconn = false;
> + }
> + } else if (ipv6h_check->version == 6) {
> + if (ipv6h_check->nexthdr != IPPROTO_TCP)
> + continue;
> + seglen = ntohs(ipv6h_check->payload_len);
> + tcph_check = (struct tcphdr *)((void *)ipv6h_check +
> + sizeof(struct ipv6hdr));
> + if (ipv6h->version == 6 &&
> + ipv6_addr_cmp(&ipv6h_check->saddr, &ipv6h->saddr) &&
> + ipv6_addr_cmp(&ipv6h_check->daddr, &ipv6h->daddr)) {
> + thisconn = true;
> + } else {
> + thisconn = false;
> + }
> + } else {
> + continue;
> + }
> +
> + /* stricter criteria apply to ACKs that we may filter
> + * 3 reserved flags must be unset to avoid future breakage
> + * ECE/CWR/NS can be safely ignored
> + * ACK must be set
> + * All other flags URG/PSH/RST/SYN/FIN must be unset
> + * must be 'pure' ACK, contain zero bytes of segment data
> + * options are ignored
> + */
> + if ((tcp_flag_word(tcph) &
> + cpu_to_be32(0x00120000)) != TCP_FLAG_ACK) {
> + continue;
> + } else if (((tcp_flag_word(tcph_check) &
> + cpu_to_be32(0x0E3F0000)) != TCP_FLAG_ACK) ||
> + ((seglen - 4 * tcph_check->doff) != 0)) {
> + pure_ack = false;
> + } else {
> + pure_ack = true;
> + }
> +
> + /* if we find an ACK belonging to a different connection
> + * continue checking for other ACKs this round however
> + * restart checking from the other connection next time.
> + */
> + if (thisconn && (tcph_check->source != tcph->source ||
> + tcph_check->dest != tcph->dest)) {
> + thisconn = false;
> + }
> +
> + /* new ack sequence must be greater
> + */
> + if (thisconn &&
> + (ntohl(tcph_check->ack_seq) > ntohl(tcph->ack_seq)))
> + continue;
> +
> + /* DupACKs with an equal sequence number shouldn't be filtered,
> + * but we can filter if the triggering packet is a SACK
> + */
> + if (thisconn &&
> + (ntohl(tcph_check->ack_seq) == ntohl(tcph->ack_seq))) {
> + /* inspired by tcp_parse_options in tcp_input.c */
> + bool sack = false;
> + int length = (tcph->doff * 4) - sizeof(struct tcphdr);
> + const u8 *ptr = (const u8 *)(tcph + 1);
> +
> + while (length > 0) {
> + int opcode = *ptr++;
> + int opsize;
> +
> + if (opcode == TCPOPT_EOL)
> + break;
> + if (opcode == TCPOPT_NOP) {
> + length--;
> + continue;
> + }
> + opsize = *ptr++;
> + if (opsize < 2 || opsize > length)
> + break;
> + if (opcode == TCPOPT_SACK) {
> + sack = true;
> + break;
> + }
> + ptr += opsize - 2;
> + length -= opsize;
> + }
> + if (!sack)
> + continue;
> + }
> +
> + /* somewhat complicated control flow for 'conservative'
> + * ACK filtering that aims to be more polite to slow-start and
> + * in the presence of packet loss.
> + * does not filter if there is one 'redundant' ACK in the queue.
> + * 'data' ACKs won't be filtered but do count as redundant ACKs.
> + */
> + if (thisconn) {
> + thisconn_seen_last = true;
> + /* if aggressive and this is a data ack we can skip
> + * checking it next time.
> + */
> + thisconn_checked_to = (aggressive && !pure_ack) ?
> + skb_check : skb_check_prev;
> + /* the first pure ack for this connection.
> + * record where it is, but only break if aggressive
> + * or already seen data ack from the same connection
> + */
> + if (pure_ack && !thisconn_ack) {
> + thisconn_ack = skb_check_prev;
> + if (aggressive || thisconn_redundant_seen)
> + break;
> + /* data ack or subsequent pure ack */
> + } else {
> + thisconn_redundant_seen = true;
> + /* this is the second ack for this connection
> + * break to filter the first pure ack
> + */
> + if (thisconn_ack)
> + break;
> + }
> + /* track packets from non-matching tcp connections that will
> + * need evaluation on the next run.
> + * if there are packets from both the matching connection and
> + * others that requre checking next run, track which was updated
> + * last and return the older of the two to ensure full coverage.
> + * if a non-matching pure ack has been seen, cannot skip any
> + * further on the next run so don't update.
> + */
> + } else if (!otherconn_ack_seen) {
> + thisconn_seen_last = false;
> + if (pure_ack) {
> + otherconn_ack_seen = true;
> + /* if aggressive we don't care about old data,
> + * start from the pure ack.
> + * otherwise if there is a previous data ack,
> + * start checking from it next time.
> + */
> + if (aggressive || !otherconn_checked_to)
> + otherconn_checked_to = skb_check_prev;
> + } else {
> + otherconn_checked_to = aggressive ?
> + skb_check : skb_check_prev;
> + }
> + }
> + }
> +
> + /* skb_check is reused at this point
> + * it is the pure ACK to be filtered (if any)
> + */
> + skb_check = NULL;
> +
> + /* next time start checking from the older/nearest to head of unfiltered
> + * but important tcp packets from this connection and other connections.
> + * if none seen, start after the last packet evaluated in the loop.
> + */
> + if (thisconn_checked_to && otherconn_checked_to)
> + flow->ackcheck = thisconn_seen_last ?
> + otherconn_checked_to : thisconn_checked_to;
> + else if (thisconn_checked_to)
> + flow->ackcheck = thisconn_checked_to;
> + else if (otherconn_checked_to)
> + flow->ackcheck = otherconn_checked_to;
> + else
> + flow->ackcheck = skb_check_prev;
> +
> + /* if filtering, the pure ACK from the flow queue */
> + if (thisconn_ack && (aggressive || thisconn_redundant_seen)) {
> + if (PTR_ERR(thisconn_ack) == -1) {
> + skb_check = flow->head;
> + flow->head = flow->head->next;
> + } else {
> + skb_check = thisconn_ack->next;
> + thisconn_ack->next = thisconn_ack->next->next;
> + }
> + }
> +
> + /* we just filtered that ack, fix up the list */
> + if (flow->ackcheck == skb_check)
> + flow->ackcheck = thisconn_ack;
> + /* check the entire flow queue next time */
> + if (PTR_ERR(flow->ackcheck) == -1)
> + flow->ackcheck = NULL;
> +
> + return skb_check;
> +}
> +
> +static inline u32 cake_overhead(struct cake_sched_data *q, u32 in)
> +{
> + u32 out = in + q->rate_overhead;
> +
> + if (q->rate_mpu && out < q->rate_mpu)
> + out = q->rate_mpu;
> +
> + if (q->rate_flags & CAKE_FLAG_ATM) {
> + out += 47;
> + out /= 48;
> + out *= 53;
> + } else if (q->rate_flags & CAKE_FLAG_PTM) {
> + /* Add one byte per 64 bytes or part thereof.
> + * This is conservative and easier to calculate than the
> + * precise value.
> + */
> + out += (out / 64) + !!(out % 64);
> + }
> +
> + return out;
> +}
> +
> +static inline cobalt_time_t cake_ewma(cobalt_time_t avg, cobalt_time_t sample,
> + u32 shift)
> +{
> + avg -= avg >> shift;
> + avg += sample >> shift;
> + return avg;
> +}
> +
> +static inline void cake_heap_swap(struct cake_sched_data *q, u16 i, u16 j)
> +{
> + struct cake_heap_entry ii = q->overflow_heap[i];
> + struct cake_heap_entry jj = q->overflow_heap[j];
> +
> + q->overflow_heap[i] = jj;
> + q->overflow_heap[j] = ii;
> +
> + q->tins[ii.t].overflow_idx[ii.b] = j;
> + q->tins[jj.t].overflow_idx[jj.b] = i;
> +}
> +
> +static inline u32 cake_heap_get_backlog(const struct cake_sched_data *q, u16 i)
> +{
> + struct cake_heap_entry ii = q->overflow_heap[i];
> +
> + return q->tins[ii.t].backlogs[ii.b];
> +}
> +
> +static void cake_heapify(struct cake_sched_data *q, u16 i)
> +{
> + static const u32 a = CAKE_MAX_TINS * CAKE_QUEUES;
> + u32 m = i;
> + u32 mb = cake_heap_get_backlog(q, m);
> +
> + while (m < a) {
> + u32 l = m + m + 1;
> + u32 r = l + 1;
> +
> + if (l < a) {
> + u32 lb = cake_heap_get_backlog(q, l);
> +
> + if (lb > mb) {
> + m = l;
> + mb = lb;
> + }
> + }
> +
> + if (r < a) {
> + u32 rb = cake_heap_get_backlog(q, r);
> +
> + if (rb > mb) {
> + m = r;
> + mb = rb;
> + }
> + }
> +
> + if (m != i) {
> + cake_heap_swap(q, i, m);
> + i = m;
> + } else {
> + break;
> + }
> + }
> +}
> +
> +static void cake_heapify_up(struct cake_sched_data *q, u16 i)
> +{
> + while (i > 0 && i < CAKE_MAX_TINS * CAKE_QUEUES) {
> + u16 p = (i - 1) >> 1;
> + u32 ib = cake_heap_get_backlog(q, i);
> + u32 pb = cake_heap_get_backlog(q, p);
> +
> + if (ib > pb) {
> + cake_heap_swap(q, i, p);
> + i = p;
> + } else {
> + break;
> + }
> + }
> +}
> +
> +static void cake_advance_shaper(struct cake_sched_data *q,
> + struct cake_tin_data *b, u32 len, u64 now, bool drop)
> +{
> + /* charge packet bandwidth to this tin
> + * and to the global shaper.
> + */
> + if (q->rate_ns) {
> + s64 tdiff1 = b->tin_time_next_packet - now;
> + s64 tdiff2 = (len * (u64)b->tin_rate_ns) >> b->tin_rate_shft;
> + s64 tdiff3 = (len * (u64)q->rate_ns) >> q->rate_shft;
> + s64 tdiff4 = (len * (u64)q->rate_ns) >> (q->rate_shft - 2);
> +
> + if (tdiff1 < 0)
> + b->tin_time_next_packet += tdiff2;
> + else if (tdiff1 < tdiff2)
> + b->tin_time_next_packet = now + tdiff2;
> +
> + q->time_next_packet += tdiff3;
> + if (!drop)
> + q->failsafe_next_packet += tdiff4;
> + }
> +}
> +
> +static unsigned int cake_drop(struct Qdisc *sch, struct sk_buff **to_free)
> +{
> + struct cake_sched_data *q = qdisc_priv(sch);
> + struct sk_buff *skb;
> + u32 idx = 0, tin = 0, len;
> + struct cake_tin_data *b;
> + struct cake_flow *flow;
> + struct cake_heap_entry qq;
> + u64 now = cobalt_get_time();
> +
> + if (!q->overflow_timeout) {
> + int i;
> + /* Build fresh max-heap */
> + for (i = CAKE_MAX_TINS * CAKE_QUEUES / 2; i >= 0; i--)
> + cake_heapify(q, i);
> + }
> + q->overflow_timeout = 65535;
> +
> + /* select longest queue for pruning */
> + qq = q->overflow_heap[0];
> + tin = qq.t;
> + idx = qq.b;
> +
> + b = &q->tins[tin];
> + flow = &b->flows[idx];
> + skb = dequeue_head(flow);
> + if (unlikely(!skb)) {
> + /* heap has gone wrong, rebuild it next time */
> + q->overflow_timeout = 0;
> + return idx + (tin << 16);
> + }
> +
> + if (cobalt_queue_full(&flow->cvars, &b->cparams, now))
> + b->unresponsive_flow_count++;
> +
> + len = qdisc_pkt_len(skb);
> + q->buffer_used -= skb->truesize;
> + b->backlogs[idx] -= len;
> + b->tin_backlog -= len;
> + sch->qstats.backlog -= len;
> + qdisc_tree_reduce_backlog(sch, 1, len);
> +
> + b->tin_dropped++;
> + sch->qstats.drops++;
> +
> + if (q->rate_flags & CAKE_FLAG_INGRESS)
> + cake_advance_shaper(q, b, cake_overhead(q, len), now, true);
> +
> + __qdisc_drop(skb, to_free);
We use __qdisc_drop here, but other variants elsewhere. Why?
> + sch->q.qlen--;
> + cake_heapify(q, 0);
> +
> + return idx + (tin << 16);
> +}
> +
> +static inline void cake_wash_diffserv(struct sk_buff *skb)
> +{
> + switch (skb->protocol) {
> + case htons(ETH_P_IP):
> + ipv4_change_dsfield(ip_hdr(skb), INET_ECN_MASK, 0);
> + break;
> + case htons(ETH_P_IPV6):
> + ipv6_change_dsfield(ipv6_hdr(skb), INET_ECN_MASK, 0);
> + break;
> + default:
> + break;
> + };
> +}
> +
> +static inline u8 cake_handle_diffserv(struct sk_buff *skb, u16 wash)
> +{
> + u8 dscp;
> +
> + switch (skb->protocol) {
> + case htons(ETH_P_IP):
> + dscp = ipv4_get_dsfield(ip_hdr(skb)) >> 2;
> + if (wash && dscp)
> + ipv4_change_dsfield(ip_hdr(skb), INET_ECN_MASK, 0);
> + return dscp;
> +
> + case htons(ETH_P_IPV6):
> + dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> 2;
> + if (wash && dscp)
> + ipv6_change_dsfield(ipv6_hdr(skb), INET_ECN_MASK, 0);
> + return dscp;
> +
> + case htons(ETH_P_ARP):
> + return 0x38; /* CS7 - Net Control */
> +
> + default:
> + /* If there is no Diffserv field, treat as best-effort */
> + return 0;
> + };
> +}
> +
> +static void cake_reconfigure(struct Qdisc *sch);
> +
> +static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch,
> + struct sk_buff **to_free)
> +{
> + struct cake_sched_data *q = qdisc_priv(sch);
> + u32 idx, tin;
> + struct cake_tin_data *b;
> + struct cake_flow *flow;
> + /* signed len to handle corner case filtered ACK larger than trigger */
> + int len = qdisc_pkt_len(skb);
> + u64 now = cobalt_get_time();
> + struct sk_buff *skb_filtered_ack = NULL;
> +
> + /* extract the Diffserv Precedence field, if it exists */
> + /* and clear DSCP bits if washing */
> + if (q->tin_mode != CAKE_MODE_BESTEFFORT) {
> + tin = q->tin_index[cake_handle_diffserv(skb,
> + q->rate_flags & CAKE_FLAG_WASH)];
> + if (unlikely(tin >= q->tin_cnt))
> + tin = 0;
> + } else {
> + tin = 0;
> + if (q->rate_flags & CAKE_FLAG_WASH)
> + cake_wash_diffserv(skb);
> + }
> +
> + b = &q->tins[tin];
> +
> + /* choose flow to insert into */
> + idx = cake_hash(b, skb, q->flow_mode);
> + flow = &b->flows[idx];
> +
> + /* ensure shaper state isn't stale */
> + if (!b->tin_backlog) {
> + if (b->tin_time_next_packet < now)
> + b->tin_time_next_packet = now;
> +
> + if (!sch->q.qlen) {
> + if (q->time_next_packet < now) {
> + q->failsafe_next_packet = now;
> + q->time_next_packet = now;
> + } else if (q->time_next_packet > now && q->failsafe_next_packet > now) {
> + u64 next_time = (q->time_next_packet < q->failsafe_next_packet)
> + ? q->time_next_packet : q->failsafe_next_packet;
> + sch->qstats.overlimits++;
> + qdisc_watchdog_schedule_ns(&q->watchdog, next_time);
> + }
> + }
> + }
> +
> + if (unlikely(len > b->max_skblen))
> + b->max_skblen = len;
> +
> + /* Split GSO aggregates if they're likely to impair flow isolation
> + * or if we need to know individual packet sizes for framing overhead.
> + */
> +
> + if (skb_is_gso(skb)) {
> + struct sk_buff *segs, *nskb;
> + netdev_features_t features = netif_skb_features(skb);
> + /* signed slen to handle corner case
> + * suppressed ACK larger than trigger
> + */
> + int slen = 0;
> +
> + segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
> + if (IS_ERR_OR_NULL(segs))
> + return qdisc_drop(skb, sch, to_free);
Why __qdisc_drop elsewhere?
> + while (segs) {
> + nskb = segs->next;
> + segs->next = NULL;
> + qdisc_skb_cb(segs)->pkt_len = segs->len;
> + cobalt_set_enqueue_time(segs, now);
> + flow_queue_add(flow, segs);
> +
> + if (q->rate_flags & CAKE_FLAG_ACK_FILTER)
> + skb_filtered_ack = ack_filter(flow, q->rate_flags & CAKE_FLAG_ACK_AGGRESSIVE);
> +
> + if (skb_filtered_ack) {
> + b->ack_drops++;
> + b->bytes += skb_filtered_ack->len;
> + slen += segs->len - skb_filtered_ack->len;
> + q->buffer_used += segs->truesize -
> + skb_filtered_ack->truesize;
> + if (q->rate_flags & CAKE_FLAG_INGRESS)
> + cake_advance_shaper(q, b, cake_overhead(q, skb_filtered_ack->len), now, true);
> +
> + qdisc_tree_reduce_backlog(sch, 1,
> + qdisc_pkt_len(skb_filtered_ack));
> + consume_skb(skb_filtered_ack);
> + } else {
> + sch->q.qlen++;
> + slen += segs->len;
> + q->buffer_used += segs->truesize;
> + }
> + b->packets++;
> + segs = nskb;
> + }
> + /* stats */
> + b->bytes += slen;
> + b->backlogs[idx] += slen;
> + b->tin_backlog += slen;
> + sch->qstats.backlog += slen;
> + q->avg_window_bytes += slen;
> +
> + qdisc_tree_reduce_backlog(sch, 1, len);
> + consume_skb(skb);
Still trying to figure out this
> + } else {
> + /* not splitting */
> + cobalt_set_enqueue_time(skb, now);
> + flow_queue_add(flow, skb);
> +
> + if (q->rate_flags & CAKE_FLAG_ACK_FILTER)
> + skb_filtered_ack = ack_filter(flow, (q->rate_flags & CAKE_FLAG_ACK_AGGRESSIVE));
Could just pass q->rate_flags and sort it out there.
> + if (skb_filtered_ack) {
> + b->ack_drops++;
> + b->bytes += qdisc_pkt_len(skb_filtered_ack);
> + len -= qdisc_pkt_len(skb_filtered_ack);
> + q->buffer_used += skb->truesize -
> + skb_filtered_ack->truesize;
> + if (q->rate_flags & CAKE_FLAG_INGRESS)
> + cake_advance_shaper(q, b, cake_overhead(q, skb_filtered_ack->len), now, true);
> +
> + qdisc_tree_reduce_backlog(sch, 1,
> + qdisc_pkt_len(skb_filtered_ack));
> + consume_skb(skb_filtered_ack);
> + } else {
> + sch->q.qlen++;
> + q->buffer_used += skb->truesize;
> + }
> + /* stats */
> + b->packets++;
> + b->bytes += len;
> + b->backlogs[idx] += len;
> + b->tin_backlog += len;
> + sch->qstats.backlog += len;
> + q->avg_window_bytes += len;
> + }
> +
> + if (q->overflow_timeout)
> + cake_heapify_up(q, b->overflow_idx[idx]);
> +
> + /* incoming bandwidth capacity estimate */
> + if (q->rate_flags & CAKE_FLAG_AUTORATE_INGRESS) {
> + u64 packet_interval = now - q->last_packet_time;
> +
> + if (packet_interval > NSEC_PER_SEC)
> + packet_interval = NSEC_PER_SEC;
I do not understand this. Why?
> +
> + /* filter out short-term bursts, eg. wifi aggregation */
> + q->avg_packet_interval = cake_ewma(q->avg_packet_interval,
> + packet_interval,
> + packet_interval > q->avg_packet_interval ? 2 : 8);
> +
> + q->last_packet_time = now;
> +
> + if (packet_interval > q->avg_packet_interval) {
> + u64 window_interval = now - q->avg_window_begin;
> + u64 b = q->avg_window_bytes * (u64)NSEC_PER_SEC;
> +
> + do_div(b, window_interval);
> + q->avg_peak_bandwidth =
> + cake_ewma(q->avg_peak_bandwidth, b,
> + b > q->avg_peak_bandwidth ? 2 : 8);
> + q->avg_window_bytes = 0;
> + q->avg_window_begin = now;
> +
> + if (q->rate_flags & CAKE_FLAG_AUTORATE_INGRESS &&
> + now - q->last_reconfig_time >
> + (NSEC_PER_SEC / 4)) {
> + q->rate_bps = (q->avg_peak_bandwidth * 15) >> 4;
> + cake_reconfigure(sch);
> + }
> + }
> + } else {
> + q->avg_window_bytes = 0;
> + q->last_packet_time = now;
> + }
> +
> + /* flowchain */
> + if (!flow->set || flow->set == CAKE_SET_DECAYING) {
> + struct cake_host *srchost = &b->hosts[flow->srchost];
> + struct cake_host *dsthost = &b->hosts[flow->dsthost];
> + u16 host_load = 1;
> +
> + if (!flow->set) {
> + list_add_tail(&flow->flowchain, &b->new_flows);
> + } else {
> + b->decaying_flow_count--;
> + list_move_tail(&flow->flowchain, &b->new_flows);
> + }
> + flow->set = CAKE_SET_SPARSE;
> + b->sparse_flow_count++;
> +
> + if ((q->flow_mode & CAKE_FLOW_DUAL_SRC) == CAKE_FLOW_DUAL_SRC)
> + host_load = max(host_load, srchost->srchost_refcnt);
> +
> + if ((q->flow_mode & CAKE_FLOW_DUAL_DST) == CAKE_FLOW_DUAL_DST)
> + host_load = max(host_load, dsthost->dsthost_refcnt);
> +
> + flow->deficit = (b->flow_quantum * quantum_div[host_load]) >> 16;
> + } else if (flow->set == CAKE_SET_SPARSE_WAIT) {
> + /* this flow was empty, accounted as a sparse flow, but actually
> + * in the bulk rotation.
> + */
> + flow->set = CAKE_SET_BULK;
> + b->sparse_flow_count--;
> + b->bulk_flow_count++;
> + }
> +
> + if (q->buffer_used > q->buffer_max_used)
> + q->buffer_max_used = q->buffer_used;
> +
> + if (q->buffer_used > q->buffer_limit) {
> + u32 dropped = 0;
> +
> + while (q->buffer_used > q->buffer_limit) {
> + dropped++;
> + cake_drop(sch, to_free);
> + }
> + b->drop_overlimit += dropped;
> + }
> + return NET_XMIT_SUCCESS;
> +}
> +
> +static struct sk_buff *cake_dequeue_one(struct Qdisc *sch)
> +{
> + struct cake_sched_data *q = qdisc_priv(sch);
> + struct cake_tin_data *b = &q->tins[q->cur_tin];
> + struct cake_flow *flow = &b->flows[q->cur_flow];
> + struct sk_buff *skb = NULL;
> + u32 len;
> +
> + /* WARN_ON(flow != container_of(vars, struct cake_flow, cvars)); */
I should have deleted this comment.
> +
> + if (flow->head) {
> + skb = dequeue_head(flow);
> + len = qdisc_pkt_len(skb);
> + b->backlogs[q->cur_flow] -= len;
> + b->tin_backlog -= len;
> + sch->qstats.backlog -= len;
> + q->buffer_used -= skb->truesize;
> + sch->q.qlen--;
> +
> + if (q->overflow_timeout)
> + cake_heapify(q, b->overflow_idx[q->cur_flow]);
> + }
> + return skb;
> +}
> +
> +/* Discard leftover packets from a tin no longer in use. */
> +static void cake_clear_tin(struct Qdisc *sch, u16 tin)
> +{
> + struct cake_sched_data *q = qdisc_priv(sch);
> + struct sk_buff *skb;
> +
> + q->cur_tin = tin;
> + for (q->cur_flow = 0; q->cur_flow < CAKE_QUEUES; q->cur_flow++)
> + while (!!(skb = cake_dequeue_one(sch)))
> + kfree_skb(skb);
> +}
> +
> +static struct sk_buff *cake_dequeue(struct Qdisc *sch)
> +{
> + struct cake_sched_data *q = qdisc_priv(sch);
> + struct sk_buff *skb;
> + struct cake_tin_data *b = &q->tins[q->cur_tin];
> + struct cake_flow *flow;
> + struct cake_host *srchost, *dsthost;
> + struct list_head *head;
> + u32 len;
> + u16 host_load;
> + cobalt_time_t now = ktime_get_ns();
> + cobalt_time_t delay;
> + bool first_flow = true;
> +
> +begin:
> + if (!sch->q.qlen)
> + return NULL;
> +
> + /* global hard shaper */
> + if (q->time_next_packet > now && q->failsafe_next_packet > now) {
> + u64 next_time = (q->time_next_packet < q->failsafe_next_packet)
> + ? q->time_next_packet : q->failsafe_next_packet;
> + sch->qstats.overlimits++;
> + qdisc_watchdog_schedule_ns(&q->watchdog, next_time);
> + return NULL;
> + }
> +
> + /* Choose a class to work on. */
> + if (!q->rate_ns) {
> + /* In unlimited mode, can't rely on shaper timings, just balance
> + * with DRR
> + */
> + while (b->tin_deficit < 0 ||
> + !(b->sparse_flow_count + b->bulk_flow_count)) {
> + if (b->tin_deficit <= 0)
> + b->tin_deficit += b->tin_quantum_band;
> +
> + q->cur_tin++;
> + b++;
> + if (q->cur_tin >= q->tin_cnt) {
> + q->cur_tin = 0;
> + b = q->tins;
> + }
> + }
> + } else {
> + /* In shaped mode, choose:
> + * - Highest-priority tin with queue and meeting schedule, or
> + * - The earliest-scheduled tin with queue.
> + */
> + int tin, best_tin = 0;
> + s64 best_time = 0xFFFFFFFFFFFFUL;
> +
> + for (tin = 0; tin < q->tin_cnt; tin++) {
> + b = q->tins + tin;
> + if ((b->sparse_flow_count + b->bulk_flow_count) > 0) {
> + s64 tdiff = b->tin_time_next_packet - now;
> +
> + if (tdiff <= 0 || tdiff <= best_time) {
> + best_time = tdiff;
> + best_tin = tin;
> + }
> + }
> + }
> +
> + q->cur_tin = best_tin;
> + b = q->tins + best_tin;
> + }
> +
> +retry:
> + /* service this class */
> + head = &b->decaying_flows;
> + if (!first_flow || list_empty(head)) {
> + head = &b->new_flows;
> + if (list_empty(head)) {
> + head = &b->old_flows;
> + if (unlikely(list_empty(head))) {
> + head = &b->decaying_flows;
> + if (unlikely(list_empty(head)))
> + goto begin;
> + }
> + }
> + }
> + flow = list_first_entry(head, struct cake_flow, flowchain);
> + q->cur_flow = flow - b->flows;
> + first_flow = false;
> +
> + /* triple isolation (modified DRR++) */
> + srchost = &b->hosts[flow->srchost];
> + dsthost = &b->hosts[flow->dsthost];
> + host_load = 1;
> +
> + if ((q->flow_mode & CAKE_FLOW_DUAL_SRC) == CAKE_FLOW_DUAL_SRC)
> + host_load = max(host_load, srchost->srchost_refcnt);
> +
> + if ((q->flow_mode & CAKE_FLOW_DUAL_DST) == CAKE_FLOW_DUAL_DST)
> + host_load = max(host_load, dsthost->dsthost_refcnt);
> +
> + WARN_ON(host_load > CAKE_QUEUES);
Should have nuked this also.
> +
> + /* flow isolation (DRR++) */
> + if (flow->deficit <= 0) {
> + flow->deficit += (b->flow_quantum * quantum_div[host_load] +
> + (prandom_u32() >> 16)) >> 16;
> + list_move_tail(&flow->flowchain, &b->old_flows);
> +
> + /* Keep all flows with deficits out of the sparse and decaying
> + * rotations. No non-empty flow can go into the decaying
> + * rotation, so they can't get deficits
> + */
> + if (flow->set == CAKE_SET_SPARSE) {
> + if (flow->head) {
> + b->sparse_flow_count--;
> + b->bulk_flow_count++;
> + flow->set = CAKE_SET_BULK;
> + } else {
> + /* we've moved it to the bulk rotation for
> + * correct deficit accounting but we still want
> + * to count it as a sparse flow, not a bulk one.
> + */
> + flow->set = CAKE_SET_SPARSE_WAIT;
> + }
> + }
> + goto retry;
> + }
> +
> + /* Retrieve a packet via the AQM */
> + while (1) {
> + skb = cake_dequeue_one(sch);
> + if (!skb) {
> + /* this queue was actually empty */
> + if (cobalt_queue_empty(&flow->cvars, &b->cparams, now))
> + b->unresponsive_flow_count--;
> +
> + if (flow->cvars.p_drop || flow->cvars.count ||
> + (now - flow->cvars.drop_next) < 0) {
> + /* keep in the flowchain until the state has
> + * decayed to rest
> + */
> + list_move_tail(&flow->flowchain,
> + &b->decaying_flows);
> + if (flow->set == CAKE_SET_BULK) {
> + b->bulk_flow_count--;
> + b->decaying_flow_count++;
> + } else if (flow->set == CAKE_SET_SPARSE ||
> + flow->set == CAKE_SET_SPARSE_WAIT) {
> + b->sparse_flow_count--;
> + b->decaying_flow_count++;
> + }
> + flow->set = CAKE_SET_DECAYING;
> + } else {
> + /* remove empty queue from the flowchain */
> + list_del_init(&flow->flowchain);
> + if (flow->set == CAKE_SET_SPARSE ||
> + flow->set == CAKE_SET_SPARSE_WAIT)
> + b->sparse_flow_count--;
> + else if (flow->set == CAKE_SET_BULK)
> + b->bulk_flow_count--;
> + else
> + b->decaying_flow_count--;
> +
> + flow->set = CAKE_SET_NONE;
> + srchost->srchost_refcnt--;
> + dsthost->dsthost_refcnt--;
> + }
> + goto begin;
> + }
> +
> + /* Last packet in queue may be marked, shouldn't be dropped */
> + if (!cobalt_should_drop(&flow->cvars, &b->cparams, now, skb) ||
> + !flow->head)
> + break;
> +
> + /* drop this packet, get another one */
> + if (q->rate_flags & CAKE_FLAG_INGRESS) {
> + len = cake_overhead(q, qdisc_pkt_len(skb));
> + cake_advance_shaper(q, b, len, now, true);
> + flow->deficit -= len;
> + b->tin_deficit -= len;
> + }
> + b->tin_dropped++;
> + qdisc_tree_reduce_backlog(sch, 1, qdisc_pkt_len(skb));
> + qdisc_qstats_drop(sch);
> + kfree_skb(skb);
And elsewhere I see __qdisc_drop.
> + if (q->rate_flags & CAKE_FLAG_INGRESS)
> + goto retry;
> + }
> +
> + b->tin_ecn_mark += !!flow->cvars.ecn_marked;
> + qdisc_bstats_update(sch, skb);
> +
> + len = cake_overhead(q, qdisc_pkt_len(skb));
> + flow->deficit -= len;
> + b->tin_deficit -= len;
> +
> + /* collect delay stats */
> + delay = now - cobalt_get_enqueue_time(skb);
> + b->avge_delay = cake_ewma(b->avge_delay, delay, 8);
> + b->peak_delay = cake_ewma(b->peak_delay, delay,
> + delay > b->peak_delay ? 2 : 8);
> + b->base_delay = cake_ewma(b->base_delay, delay,
> + delay < b->base_delay ? 2 : 8);
> +
> + cake_advance_shaper(q, b, len, now, false);
> + if (q->time_next_packet > now && sch->q.qlen) {
> + u64 next_time = (q->time_next_packet < q->failsafe_next_packet)
> + ? q->time_next_packet : q->failsafe_next_packet;
> + qdisc_watchdog_schedule_ns(&q->watchdog, next_time);
> + } else if (!sch->q.qlen) {
> + int i;
> +
> + for (i = 0; i < q->tin_cnt; i++) {
> + if (q->tins[i].decaying_flow_count) {
> + qdisc_watchdog_schedule_ns(&q->watchdog, now +
> + q->tins[i].cparams.target);
> + break;
> + }
> + }
> + }
> +
> + if (q->overflow_timeout)
> + q->overflow_timeout--;
> +
> + return skb;
> +}
> +
> +static void cake_reset(struct Qdisc *sch)
> +{
> + u32 c;
> +
> + for (c = 0; c < CAKE_MAX_TINS; c++)
> + cake_clear_tin(sch, c);
> +}
> +
> +static const struct nla_policy cake_policy[TCA_CAKE_MAX + 1] = {
> + [TCA_CAKE_BASE_RATE] = { .type = NLA_U32 },
> + [TCA_CAKE_DIFFSERV_MODE] = { .type = NLA_U32 },
> + [TCA_CAKE_ATM] = { .type = NLA_U32 },
> + [TCA_CAKE_FLOW_MODE] = { .type = NLA_U32 },
> + [TCA_CAKE_OVERHEAD] = { .type = NLA_S32 },
> + [TCA_CAKE_RTT] = { .type = NLA_U32 },
> + [TCA_CAKE_TARGET] = { .type = NLA_U32 },
> + [TCA_CAKE_AUTORATE] = { .type = NLA_U32 },
> + [TCA_CAKE_MEMORY] = { .type = NLA_U32 },
> + [TCA_CAKE_NAT] = { .type = NLA_U32 },
> + [TCA_CAKE_ETHERNET] = { .type = NLA_U32 },
> + [TCA_CAKE_WASH] = { .type = NLA_U32 },
> + [TCA_CAKE_MPU] = { .type = NLA_U32 },
> + [TCA_CAKE_INGRESS] = { .type = NLA_U32 },
> + [TCA_CAKE_ACK_FILTER] = { .type = NLA_U32 },
> +};
Why here?
> +
> +static void cake_set_rate(struct cake_tin_data *b, u64 rate, u32 mtu,
> + cobalt_time_t ns_target, cobalt_time_t rtt_est_ns)
> +{
> + /* convert byte-rate into time-per-byte
> + * so it will always unwedge in reasonable time.
> + */
> + static const u64 MIN_RATE = 64;
> + u64 rate_ns = 0;
> + u8 rate_shft = 0;
> + cobalt_time_t byte_target_ns;
> + u32 byte_target = mtu + (mtu >> 1);
> +
> + b->flow_quantum = 1514;
> + if (rate) {
> + b->flow_quantum = max(min(rate >> 12, 1514ULL), 300ULL);
> + rate_shft = 32;
> + rate_ns = ((u64)NSEC_PER_SEC) << rate_shft;
> + do_div(rate_ns, max(MIN_RATE, rate));
> + while (!!(rate_ns >> 32)) {
> + rate_ns >>= 1;
> + rate_shft--;
> + }
> + } /* else unlimited, ie. zero delay */
> +
> + b->tin_rate_bps = rate;
> + b->tin_rate_ns = rate_ns;
> + b->tin_rate_shft = rate_shft;
> +
> + byte_target_ns = (byte_target * rate_ns) >> rate_shft;
> +
> + b->cparams.target = max(byte_target_ns, ns_target);
> + b->cparams.interval = max(rtt_est_ns +
> + b->cparams.target - ns_target,
> + b->cparams.target * 2);
> + b->cparams.p_inc = 1 << 24; /* 1/256 */
> + b->cparams.p_dec = 1 << 20; /* 1/4096 */
> +}
> +
> +static int cake_config_besteffort(struct Qdisc *sch)
> +{
> + struct cake_sched_data *q = qdisc_priv(sch);
> + struct cake_tin_data *b = &q->tins[0];
> + u32 rate = q->rate_bps;
> + u32 mtu = psched_mtu(qdisc_dev(sch));
> +
> + q->tin_cnt = 1;
> +
> + q->tin_index = besteffort;
> + q->tin_order = normal_order;
> +
> + cake_set_rate(b, rate, mtu, US2TIME(q->target), US2TIME(q->interval));
> + b->tin_quantum_band = 65535;
> + b->tin_quantum_prio = 65535;
> +
> + return 0;
> +}
> +
> +static int cake_config_precedence(struct Qdisc *sch)
> +{
> + /* convert high-level (user visible) parameters into internal format */
> + struct cake_sched_data *q = qdisc_priv(sch);
> + u32 rate = q->rate_bps;
> + u32 mtu = psched_mtu(qdisc_dev(sch));
> + u32 quantum1 = 256;
> + u32 quantum2 = 256;
> + u32 i;
> +
> + q->tin_cnt = 8;
> + q->tin_index = precedence;
> + q->tin_order = normal_order;
> +
> + for (i = 0; i < q->tin_cnt; i++) {
> + struct cake_tin_data *b = &q->tins[i];
> +
> + cake_set_rate(b, rate, mtu, US2TIME(q->target),
> + US2TIME(q->interval));
> +
> + b->tin_quantum_prio = max_t(u16, 1U, quantum1);
> + b->tin_quantum_band = max_t(u16, 1U, quantum2);
> +
> + /* calculate next class's parameters */
> + rate *= 7;
> + rate >>= 3;
> +
> + quantum1 *= 3;
> + quantum1 >>= 1;
> +
> + quantum2 *= 7;
> + quantum2 >>= 3;
> + }
> +
> + return 0;
> +}
> +
> +/* List of known Diffserv codepoints:
> + *
> + * Least Effort (CS1)
> + * Best Effort (CS0)
> + * Max Reliability & LLT "Lo" (TOS1)
> + * Max Throughput (TOS2)
> + * Min Delay (TOS4)
> + * LLT "La" (TOS5)
> + * Assured Forwarding 1 (AF1x) - x3
> + * Assured Forwarding 2 (AF2x) - x3
> + * Assured Forwarding 3 (AF3x) - x3
> + * Assured Forwarding 4 (AF4x) - x3
> + * Precedence Class 2 (CS2)
> + * Precedence Class 3 (CS3)
> + * Precedence Class 4 (CS4)
> + * Precedence Class 5 (CS5)
> + * Precedence Class 6 (CS6)
> + * Precedence Class 7 (CS7)
> + * Voice Admit (VA)
> + * Expedited Forwarding (EF)
> +
> + * Total 25 codepoints.
> + */
> +
> +/* List of traffic classes in RFC 4594:
> + * (roughly descending order of contended priority)
> + * (roughly ascending order of uncontended throughput)
> + *
> + * Network Control (CS6,CS7) - routing traffic
> + * Telephony (EF,VA) - aka. VoIP streams
> + * Signalling (CS5) - VoIP setup
> + * Multimedia Conferencing (AF4x) - aka. video calls
> + * Realtime Interactive (CS4) - eg. games
> + * Multimedia Streaming (AF3x) - eg. YouTube, NetFlix, Twitch
> + * Broadcast Video (CS3)
> + * Low Latency Data (AF2x,TOS4) - eg. database
> + * Ops, Admin, Management (CS2,TOS1) - eg. ssh
> + * Standard Service (CS0 & unrecognised codepoints)
> + * High Throughput Data (AF1x,TOS2) - eg. web traffic
> + * Low Priority Data (CS1) - eg. BitTorrent
> +
> + * Total 12 traffic classes.
> + */
> +
> +static int cake_config_diffserv8(struct Qdisc *sch)
> +{
> +/* Pruned list of traffic classes for typical applications:
> + *
> + * Network Control (CS6, CS7)
> + * Minimum Latency (EF, VA, CS5, CS4)
> + * Interactive Shell (CS2, TOS1)
> + * Low Latency Transactions (AF2x, TOS4)
> + * Video Streaming (AF4x, AF3x, CS3)
> + * Bog Standard (CS0 etc.)
> + * High Throughput (AF1x, TOS2)
> + * Background Traffic (CS1)
> + *
> + * Total 8 traffic classes.
> + */
> +
> + struct cake_sched_data *q = qdisc_priv(sch);
> + u32 rate = q->rate_bps;
> + u32 mtu = psched_mtu(qdisc_dev(sch));
> + u32 quantum1 = 256;
> + u32 quantum2 = 256;
> + u32 i;
> +
> + q->tin_cnt = 8;
> +
> + /* codepoint to class mapping */
> + q->tin_index = diffserv8;
> + q->tin_order = normal_order;
> +
> + /* class characteristics */
> + for (i = 0; i < q->tin_cnt; i++) {
> + struct cake_tin_data *b = &q->tins[i];
> +
> + cake_set_rate(b, rate, mtu, US2TIME(q->target),
> + US2TIME(q->interval));
> +
> + b->tin_quantum_prio = max_t(u16, 1U, quantum1);
> + b->tin_quantum_band = max_t(u16, 1U, quantum2);
> +
> + /* calculate next class's parameters */
> + rate *= 7;
> + rate >>= 3;
> +
> + quantum1 *= 3;
> + quantum1 >>= 1;
> +
> + quantum2 *= 7;
> + quantum2 >>= 3;
> + }
> +
> + return 0;
> +}
> +
> +static int cake_config_diffserv4(struct Qdisc *sch)
> +{
> +/* Further pruned list of traffic classes for four-class system:
> + *
> + * Latency Sensitive (CS7, CS6, EF, VA, CS5, CS4)
> + * Streaming Media (AF4x, AF3x, CS3, AF2x, TOS4, CS2, TOS1)
> + * Best Effort (CS0, AF1x, TOS2, and those not specified)
> + * Background Traffic (CS1)
> + *
> + * Total 4 traffic classes.
> + */
> +
> + struct cake_sched_data *q = qdisc_priv(sch);
> + u32 rate = q->rate_bps;
> + u32 mtu = psched_mtu(qdisc_dev(sch));
> + u32 quantum = 1024;
> +
> + q->tin_cnt = 4;
> +
> + /* codepoint to class mapping */
> + q->tin_index = diffserv4;
> + q->tin_order = bulk_order;
> +
> + /* class characteristics */
> + cake_set_rate(&q->tins[0], rate, mtu,
> + US2TIME(q->target), US2TIME(q->interval));
> + cake_set_rate(&q->tins[1], rate >> 4, mtu,
> + US2TIME(q->target), US2TIME(q->interval));
> + cake_set_rate(&q->tins[2], rate >> 1, mtu,
> + US2TIME(q->target), US2TIME(q->interval));
> + cake_set_rate(&q->tins[3], rate >> 2, mtu,
> + US2TIME(q->target), US2TIME(q->interval));
> +
> + /* priority weights */
> + q->tins[0].tin_quantum_prio = quantum;
> + q->tins[1].tin_quantum_prio = quantum >> 4;
> + q->tins[2].tin_quantum_prio = quantum << 2;
> + q->tins[3].tin_quantum_prio = quantum << 4;
> +
> + /* bandwidth-sharing weights */
> + q->tins[0].tin_quantum_band = quantum;
> + q->tins[1].tin_quantum_band = quantum >> 4;
> + q->tins[2].tin_quantum_band = quantum >> 1;
> + q->tins[3].tin_quantum_band = quantum >> 2;
> +
> + return 0;
> +}
> +
> +static int cake_config_diffserv3(struct Qdisc *sch)
> +{
> +/* Simplified Diffserv structure with 3 tins.
> + * Low Priority (CS1)
> + * Best Effort
> + * Latency Sensitive (TOS4, VA, EF, CS6, CS7)
> + */
> + struct cake_sched_data *q = qdisc_priv(sch);
> + u32 rate = q->rate_bps;
> + u32 mtu = psched_mtu(qdisc_dev(sch));
> + u32 quantum = 1024;
> +
> + q->tin_cnt = 3;
> +
> + /* codepoint to class mapping */
> + q->tin_index = diffserv3;
> + q->tin_order = bulk_order;
> +
> + /* class characteristics */
> + cake_set_rate(&q->tins[0], rate, mtu,
> + US2TIME(q->target), US2TIME(q->interval));
> + cake_set_rate(&q->tins[1], rate >> 4, mtu,
> + US2TIME(q->target), US2TIME(q->interval));
> + cake_set_rate(&q->tins[2], rate >> 2, mtu,
> + US2TIME(q->target), US2TIME(q->target));
> +
> + /* priority weights */
> + q->tins[0].tin_quantum_prio = quantum;
> + q->tins[1].tin_quantum_prio = quantum >> 4;
> + q->tins[2].tin_quantum_prio = quantum << 4;
> +
> + /* bandwidth-sharing weights */
> + q->tins[0].tin_quantum_band = quantum;
> + q->tins[1].tin_quantum_band = quantum >> 4;
> + q->tins[2].tin_quantum_band = quantum >> 2;
> +
> + return 0;
> +}
> +
> +static int cake_config_diffserv_llt(struct Qdisc *sch)
> +{
> +/* Diffserv structure specialised for Latency-Loss-Tradeoff spec.
> + * Loss Sensitive (TOS1, TOS2)
> + * Best Effort
> + * Latency Sensitive (TOS4, TOS5, VA, EF)
> + * Low Priority (CS1)
> + * Network Control (CS6, CS7)
> + */
> + struct cake_sched_data *q = qdisc_priv(sch);
> + u32 rate = q->rate_bps;
> + u32 mtu = psched_mtu(qdisc_dev(sch));
> +
> + q->tin_cnt = 5;
> +
> + /* codepoint to class mapping */
> + q->tin_index = diffserv_llt;
> + q->tin_order = normal_order;
> +
> + /* class characteristics */
> + cake_set_rate(&q->tins[5], rate, mtu,
> + US2TIME(q->target), US2TIME(q->interval));
> +
> + cake_set_rate(&q->tins[0], rate / 3, mtu,
> + US2TIME(q->target * 4), US2TIME(q->interval * 4));
> + cake_set_rate(&q->tins[1], rate / 3, mtu,
> + US2TIME(q->target), US2TIME(q->interval));
> + cake_set_rate(&q->tins[2], rate / 3, mtu,
> + US2TIME(q->target), US2TIME(q->target));
I tend to disagree with this, without some test showing it works.
It otherwise looks like a typo, and should gain a comment, at least.
> + cake_set_rate(&q->tins[3], rate >> 4, mtu,
> + US2TIME(q->target), US2TIME(q->interval));
> + cake_set_rate(&q->tins[4], rate >> 4, mtu,
> + US2TIME(q->target * 4), US2TIME(q->interval * 4));
> +
> + /* priority weights */
> + q->tins[0].tin_quantum_prio = 2048;
> + q->tins[1].tin_quantum_prio = 2048;
> + q->tins[2].tin_quantum_prio = 2048;
> + q->tins[3].tin_quantum_prio = 16384;
> + q->tins[4].tin_quantum_prio = 32768;
> +
> + /* bandwidth-sharing weights */
> + q->tins[0].tin_quantum_band = 2048;
> + q->tins[1].tin_quantum_band = 2048;
> + q->tins[2].tin_quantum_band = 2048;
> + q->tins[3].tin_quantum_band = 256;
> + q->tins[4].tin_quantum_band = 16;
> +
> + return 5;
> +}
> +
> +static void cake_reconfigure(struct Qdisc *sch)
> +{
> + struct cake_sched_data *q = qdisc_priv(sch);
> + int c, ft;
> +
> + switch (q->tin_mode) {
> + case CAKE_MODE_BESTEFFORT:
> + ft = cake_config_besteffort(sch);
> + break;
> +
> + case CAKE_MODE_PRECEDENCE:
> + ft = cake_config_precedence(sch);
> + break;
> +
> + case CAKE_MODE_DIFFSERV8:
> + ft = cake_config_diffserv8(sch);
> + break;
> +
> + case CAKE_MODE_DIFFSERV4:
> + ft = cake_config_diffserv4(sch);
> + break;
> +
> + case CAKE_MODE_LLT:
> + ft = cake_config_diffserv_llt(sch);
> + break;
> +
> + case CAKE_MODE_DIFFSERV3:
> + default:
> + ft = cake_config_diffserv3(sch);
> + break;
> + };
> +
> + for (c = q->tin_cnt; c < CAKE_MAX_TINS; c++)
> + cake_clear_tin(sch, c);
> +
> + q->rate_ns = q->tins[ft].tin_rate_ns;
> + q->rate_shft = q->tins[ft].tin_rate_shft;
> +
> + if (q->buffer_config_limit) {
> + q->buffer_limit = q->buffer_config_limit;
> + } else if (q->rate_bps) {
> + u64 t = (u64)q->rate_bps * q->interval;
> +
> + do_div(t, USEC_PER_SEC / 4);
> + q->buffer_limit = max_t(u32, t, 4U << 20);
> + } else {
> + q->buffer_limit = ~0;
> + }
> +
> + if (1 || q->rate_bps)
> + sch->flags &= ~TCQ_F_CAN_BYPASS;
> + else
> + sch->flags |= TCQ_F_CAN_BYPASS;
If we always disable bypass we slow down things by a lot, but at least
get accurate statistics. So I'm inclined to always
sch->flags &= ~TCQ_F_CAN_BYPASS;
> + q->buffer_limit = min(q->buffer_limit, max(sch->limit * psched_mtu(qdisc_dev(sch)), q->buffer_config_limit));
> +}
> +
> +static int cake_change(struct Qdisc *sch, struct nlattr *opt)
> +{
> + struct cake_sched_data *q = qdisc_priv(sch);
> + struct nlattr *tb[TCA_CAKE_MAX + 1];
> + int err;
> +
> + if (!opt)
> + return -EINVAL;
> +
> + err = nla_parse_nested(tb, TCA_CAKE_MAX, opt, cake_policy, NULL);
> + if (err < 0)
> + return err;
> +
> + if (tb[TCA_CAKE_BASE_RATE])
> + q->rate_bps = nla_get_u32(tb[TCA_CAKE_BASE_RATE]);
> +
> + if (tb[TCA_CAKE_DIFFSERV_MODE])
> + q->tin_mode = nla_get_u32(tb[TCA_CAKE_DIFFSERV_MODE]);
> +
> + if (tb[TCA_CAKE_ATM]) {
> + q->rate_flags &= ~(CAKE_FLAG_ATM | CAKE_FLAG_PTM);
> + q->rate_flags |= nla_get_u32(tb[TCA_CAKE_ATM]) &
> + (CAKE_FLAG_ATM | CAKE_FLAG_PTM);
> + }
> +
> + if (tb[TCA_CAKE_WASH]) {
> + if (!!nla_get_u32(tb[TCA_CAKE_WASH]))
> + q->rate_flags |= CAKE_FLAG_WASH;
> + else
> + q->rate_flags &= ~CAKE_FLAG_WASH;
> + }
> +
> + if (tb[TCA_CAKE_FLOW_MODE])
> + q->flow_mode = nla_get_u32(tb[TCA_CAKE_FLOW_MODE]);
> +
> + if (tb[TCA_CAKE_NAT]) {
> + q->flow_mode &= ~CAKE_FLOW_NAT_FLAG;
> + q->flow_mode |= CAKE_FLOW_NAT_FLAG *
> + !!nla_get_u32(tb[TCA_CAKE_NAT]);
> + }
> +
> + if (tb[TCA_CAKE_OVERHEAD]) {
> + if (tb[TCA_CAKE_ETHERNET])
> + q->rate_overhead = -(nla_get_s32(tb[TCA_CAKE_ETHERNET]));
> + else
> + q->rate_overhead = -(qdisc_dev(sch)->hard_header_len);
> +
> + q->rate_overhead += nla_get_s32(tb[TCA_CAKE_OVERHEAD]);
> + }
> +
> + if (tb[TCA_CAKE_MPU])
> + q->rate_mpu = nla_get_u32(tb[TCA_CAKE_MPU]);
> +
> + if (tb[TCA_CAKE_RTT]) {
> + q->interval = nla_get_u32(tb[TCA_CAKE_RTT]);
> +
> + if (!q->interval)
> + q->interval = 1;
> + }
> +
> + if (tb[TCA_CAKE_TARGET]) {
> + q->target = nla_get_u32(tb[TCA_CAKE_TARGET]);
> +
> + if (!q->target)
> + q->target = 1;
> + }
> +
> + if (tb[TCA_CAKE_AUTORATE]) {
> + if (!!nla_get_u32(tb[TCA_CAKE_AUTORATE]))
> + q->rate_flags |= CAKE_FLAG_AUTORATE_INGRESS;
> + else
> + q->rate_flags &= ~CAKE_FLAG_AUTORATE_INGRESS;
> + }
> +
> + if (tb[TCA_CAKE_INGRESS]) {
> + if (!!nla_get_u32(tb[TCA_CAKE_INGRESS]))
> + q->rate_flags |= CAKE_FLAG_INGRESS;
> + else
> + q->rate_flags &= ~CAKE_FLAG_INGRESS;
> + }
> +
> + if (tb[TCA_CAKE_ACK_FILTER]) {
> + q->rate_flags &= ~(CAKE_FLAG_ACK_FILTER |
> + CAKE_FLAG_ACK_AGGRESSIVE);
> + q->rate_flags |= nla_get_u32(tb[TCA_CAKE_ACK_FILTER]) &
> + (CAKE_FLAG_ACK_FILTER |
> + CAKE_FLAG_ACK_AGGRESSIVE);
> + }
> +
> + if (tb[TCA_CAKE_MEMORY])
> + q->buffer_config_limit = nla_get_s32(tb[TCA_CAKE_MEMORY]);
> +
> + if (q->tins) {
> + sch_tree_lock(sch);
> + cake_reconfigure(sch);
> + sch_tree_unlock(sch);
> + }
> +
> + return 0;
> +}
> +
> +static void *cake_zalloc(size_t sz)
> +{
> + void *ptr = kzalloc(sz, GFP_KERNEL | __GFP_NOWARN);
> +
> + if (!ptr)
> + ptr = vzalloc(sz);
> + return ptr;
> +}
> +
Modern fq_codel uses kvzalloc and there isn't a __GFP_NOWARN.
> +static void cake_free(void *addr)
> +{
> + if (addr)
> + kvfree(addr);
> +}
> +
> +static void cake_destroy(struct Qdisc *sch)
> +{
> + struct cake_sched_data *q = qdisc_priv(sch);
> +
> + qdisc_watchdog_cancel(&q->watchdog);
> +
> + if (q->tins)
> + cake_free(q->tins);
> +}
> +
> +static int cake_init(struct Qdisc *sch, struct nlattr *opt)
> +{
> + struct cake_sched_data *q = qdisc_priv(sch);
> + int i, j;
> +
> + sch->limit = 10240;
> + q->tin_mode = CAKE_MODE_DIFFSERV3;
> + q->flow_mode = CAKE_FLOW_TRIPLE;
> +
> + q->rate_bps = 0; /* unlimited by default */
> +
> + q->interval = 100000; /* 100ms default */
> + q->target = 5000; /* 5ms: codel RFC argues
> + * for 5 to 10% of interval
> + */
> +
> + q->cur_tin = 0;
> + q->cur_flow = 0;
> +
> + if (opt) {
> + int err = cake_change(sch, opt);
> +
> + if (err)
> + return err;
> + }
> +
> + qdisc_watchdog_init(&q->watchdog, sch);
> +
> + quantum_div[0] = ~0;
> + for (i = 1; i <= CAKE_QUEUES; i++)
> + quantum_div[i] = 65535 / i;
> +
> + q->tins = cake_zalloc(CAKE_MAX_TINS * sizeof(struct cake_tin_data));
> + if (!q->tins)
> + goto nomem;
> +
> + for (i = 0; i < CAKE_MAX_TINS; i++) {
> + struct cake_tin_data *b = q->tins + i;
> +
> + b->perturbation = prandom_u32();
Not that it matters all that much but we probably don't need
more than one perturb.
> + INIT_LIST_HEAD(&b->new_flows);
> + INIT_LIST_HEAD(&b->old_flows);
> + INIT_LIST_HEAD(&b->decaying_flows);
> + b->sparse_flow_count = 0;
> + b->bulk_flow_count = 0;
> + b->decaying_flow_count = 0;
> +
> + for (j = 0; j < CAKE_QUEUES; j++) {
> + struct cake_flow *flow = b->flows + j;
> + u32 k = j * CAKE_MAX_TINS + i;
> +
> + INIT_LIST_HEAD(&flow->flowchain);
> + cobalt_vars_init(&flow->cvars);
> +
> + q->overflow_heap[k].t = i;
> + q->overflow_heap[k].b = j;
> + b->overflow_idx[j] = k;
> + }
> + }
> +
> + cake_reconfigure(sch);
> + q->avg_peak_bandwidth = q->rate_bps;
> + return 0;
> +
> +nomem:
> + cake_destroy(sch);
> + return -ENOMEM;
> +}
> +
> +static int cake_dump(struct Qdisc *sch, struct sk_buff *skb)
> +{
> + struct cake_sched_data *q = qdisc_priv(sch);
> + struct nlattr *opts;
> +
> + opts = nla_nest_start(skb, TCA_OPTIONS);
> + if (!opts)
> + goto nla_put_failure;
> +
> + if (nla_put_u32(skb, TCA_CAKE_BASE_RATE, q->rate_bps))
> + goto nla_put_failure;
> +
> + if (nla_put_u32(skb, TCA_CAKE_DIFFSERV_MODE, q->tin_mode))
> + goto nla_put_failure;
> +
> + if (nla_put_u32(skb, TCA_CAKE_ATM, (q->rate_flags &
> + (CAKE_FLAG_ATM | CAKE_FLAG_PTM))))
> + goto nla_put_failure;
> +
> + if (nla_put_u32(skb, TCA_CAKE_FLOW_MODE, q->flow_mode))
> + goto nla_put_failure;
> +
> + if (nla_put_u32(skb, TCA_CAKE_WASH,
> + !!(q->rate_flags & CAKE_FLAG_WASH)))
> + goto nla_put_failure;
> +
> + if (nla_put_u32(skb, TCA_CAKE_OVERHEAD, q->rate_overhead +
> + qdisc_dev(sch)->hard_header_len))
> + goto nla_put_failure;
> +
> + if (nla_put_u32(skb, TCA_CAKE_MPU, q->rate_mpu))
> + goto nla_put_failure;
> +
> + if (nla_put_u32(skb, TCA_CAKE_ETHERNET,
> + qdisc_dev(sch)->hard_header_len))
> + goto nla_put_failure;
> +
> + if (nla_put_u32(skb, TCA_CAKE_RTT, q->interval))
> + goto nla_put_failure;
> +
> + if (nla_put_u32(skb, TCA_CAKE_TARGET, q->target))
> + goto nla_put_failure;
> +
> + if (nla_put_u32(skb, TCA_CAKE_AUTORATE,
> + !!(q->rate_flags & CAKE_FLAG_AUTORATE_INGRESS)))
> + goto nla_put_failure;
> +
> + if (nla_put_u32(skb, TCA_CAKE_INGRESS,
> + !!(q->rate_flags & CAKE_FLAG_INGRESS)))
> + goto nla_put_failure;
> +
> + if (nla_put_u32(skb, TCA_CAKE_ACK_FILTER,
> + (q->rate_flags &
> + (CAKE_FLAG_ACK_FILTER | CAKE_FLAG_ACK_AGGRESSIVE))))
> + goto nla_put_failure;
> +
> + if (nla_put_u32(skb, TCA_CAKE_MEMORY, q->buffer_config_limit))
> + goto nla_put_failure;
> +
> + return nla_nest_end(skb, opts);
> +
> +nla_put_failure:
> + return -1;
> +}
> +
> +static int cake_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
> +{
> + /* reuse fq_codel stats format */
> + struct cake_sched_data *q = qdisc_priv(sch);
> + struct tc_cake_xstats *st = cake_zalloc(sizeof(*st));
Modern fq_codel uses kvzalloc.
> + int i;
> +
> + if (!st)
> + return -1;
> +
> + st->version = 5;
> + st->max_tins = TC_CAKE_MAX_TINS;
> + st->tin_cnt = q->tin_cnt;
> +
> + for (i = 0; i < q->tin_cnt; i++) {
> + struct cake_tin_data *b = &q->tins[q->tin_order[i]];
> +
> + st->threshold_rate[i] = b->tin_rate_bps;
> + st->target_us[i] = cobalt_time_to_us(b->cparams.target);
> + st->interval_us[i] = cobalt_time_to_us(b->cparams.interval);
> +
> + /* TODO FIXME: add missing aspects of these composite stats */
> + st->sent[i].packets = b->packets;
> + st->sent[i].bytes = b->bytes;
> + st->dropped[i].packets = b->tin_dropped;
> + st->ecn_marked[i].packets = b->tin_ecn_mark;
> + st->backlog[i].bytes = b->tin_backlog;
> + st->ack_drops[i].packets = b->ack_drops;
> +
> + st->peak_delay_us[i] = cobalt_time_to_us(b->peak_delay);
> + st->avge_delay_us[i] = cobalt_time_to_us(b->avge_delay);
> + st->base_delay_us[i] = cobalt_time_to_us(b->base_delay);
> +
> + st->way_indirect_hits[i] = b->way_hits;
> + st->way_misses[i] = b->way_misses;
> + st->way_collisions[i] = b->way_collisions;
> +
> + st->sparse_flows[i] = b->sparse_flow_count +
> + b->decaying_flow_count;
> + st->bulk_flows[i] = b->bulk_flow_count;
> + st->unresponse_flows[i] = b->unresponsive_flow_count;
> + st->spare[i] = 0;
> + st->max_skblen[i] = b->max_skblen;
> + }
> + st->capacity_estimate = q->avg_peak_bandwidth;
> + st->memory_limit = q->buffer_limit;
> + st->memory_used = q->buffer_max_used;
> +
> + i = gnet_stats_copy_app(d, st, sizeof(*st));
> + cake_free(st);
> + return i;
> +}
> +
> +static struct Qdisc_ops cake_qdisc_ops __read_mostly = {
> + .id = "cake",
> + .priv_size = sizeof(struct cake_sched_data),
> + .enqueue = cake_enqueue,
> + .dequeue = cake_dequeue,
> + .peek = qdisc_peek_dequeued,
> + .init = cake_init,
> + .reset = cake_reset,
> + .destroy = cake_destroy,
> + .change = cake_change,
> + .dump = cake_dump,
> + .dump_stats = cake_dump_stats,
> + .owner = THIS_MODULE,
> +};
> +
> +static int __init cake_module_init(void)
> +{
> + return register_qdisc(&cake_qdisc_ops);
> +}
> +
> +static void __exit cake_module_exit(void)
> +{
> + unregister_qdisc(&cake_qdisc_ops);
> +}
> +
> +module_init(cake_module_init)
> +module_exit(cake_module_exit)
> +MODULE_AUTHOR("Jonathan Morton");
> +MODULE_LICENSE("Dual BSD/GPL");
> +MODULE_DESCRIPTION("The Cake shaper. Version: " CAKE_VERSION);
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