/*
* CoDel - The Controlled-Delay Active Queue Management algorithm
*
* Copyright (C) 2013 Ermal Luçi <eri@FreeBSD.org>
* Copyright (C) 2011-2012 Kathleen Nichols <nichols@pollere.com>
* Copyright (C) 2011-2012 Van Jacobson <van@pollere.net>
* Copyright (C) 2012 Michael D. Taht <dave.taht@bufferbloat.net>
* Copyright (C) 2012 Eric Dumazet <edumazet@google.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions, and the following disclaimer,
* without modification.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The names of the authors may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* Alternatively, provided that this notice is retained in full, this
* software may be distributed under the terms of the GNU General
* Public License ("GPL") version 2, in which case the provisions of the
* GPL apply INSTEAD OF those given above.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*/
#include "opt_altq.h"
#include "opt_inet.h"
#include "opt_inet6.h"
#ifdef ALTQ_CODEL /* CoDel is enabled by ALTQ_CODEL option in opt_altq.h */
#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/systm.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/if_private.h>
#include <netinet/in.h>
#include <netpfil/pf/pf.h>
#include <netpfil/pf/pf_altq.h>
#include <net/altq/if_altq.h>
#include <net/altq/altq.h>
#include <net/altq/altq_codel.h>
static int codel_should_drop(struct codel *, class_queue_t *,
struct mbuf *, u_int64_t);
static void codel_Newton_step(struct codel_vars *);
static u_int64_t codel_control_law(u_int64_t t, u_int64_t, u_int32_t);
#define codel_time_after(a, b) ((int64_t)(a) - (int64_t)(b) > 0)
#define codel_time_after_eq(a, b) ((int64_t)(a) - (int64_t)(b) >= 0)
#define codel_time_before(a, b) ((int64_t)(a) - (int64_t)(b) < 0)
#define codel_time_before_eq(a, b) ((int64_t)(a) - (int64_t)(b) <= 0)
static int codel_request(struct ifaltq *, int, void *);
static int codel_enqueue(struct ifaltq *, struct mbuf *, struct altq_pktattr *);
static struct mbuf *codel_dequeue(struct ifaltq *, int);
int
codel_pfattach(struct pf_altq *a)
{
struct ifnet *ifp;
if ((ifp = ifunit(a->ifname)) == NULL || a->altq_disc == NULL)
return (EINVAL);
return (altq_attach(&ifp->if_snd, ALTQT_CODEL, a->altq_disc,
codel_enqueue, codel_dequeue, codel_request));
}
int
codel_add_altq(struct ifnet *ifp, struct pf_altq *a)
{
struct codel_if *cif;
struct codel_opts *opts;
if (ifp == NULL)
return (EINVAL);
if (!ALTQ_IS_READY(&ifp->if_snd))
return (ENODEV);
opts = &a->pq_u.codel_opts;
cif = malloc(sizeof(struct codel_if), M_DEVBUF, M_NOWAIT | M_ZERO);
if (cif == NULL)
return (ENOMEM);
cif->cif_bandwidth = a->ifbandwidth;
cif->cif_ifq = &ifp->if_snd;
cif->cl_q = malloc(sizeof(class_queue_t), M_DEVBUF, M_NOWAIT | M_ZERO);
if (cif->cl_q == NULL) {
free(cif, M_DEVBUF);
return (ENOMEM);
}
if (a->qlimit == 0)
a->qlimit = 50; /* use default. */
qlimit(cif->cl_q) = a->qlimit;
qtype(cif->cl_q) = Q_CODEL;
qlen(cif->cl_q) = 0;
qsize(cif->cl_q) = 0;
if (opts->target == 0)
opts->target = 5;
if (opts->interval == 0)
opts->interval = 100;
cif->codel.params.target = machclk_freq * opts->target / 1000;
cif->codel.params.interval = machclk_freq * opts->interval / 1000;
cif->codel.params.ecn = opts->ecn;
cif->codel.stats.maxpacket = 256;
cif->cl_stats.qlength = qlen(cif->cl_q);
cif->cl_stats.qlimit = qlimit(cif->cl_q);
/* keep the state in pf_altq */
a->altq_disc = cif;
return (0);
}
int
codel_remove_altq(struct pf_altq *a)
{
struct codel_if *cif;
if ((cif = a->altq_disc) == NULL)
return (EINVAL);
a->altq_disc = NULL;
if (cif->cl_q)
free(cif->cl_q, M_DEVBUF);
free(cif, M_DEVBUF);
return (0);
}
int
codel_getqstats(struct pf_altq *a, void *ubuf, int *nbytes, int version)
{
struct codel_if *cif;
struct codel_ifstats stats;
int error = 0;
if ((cif = altq_lookup(a->ifname, ALTQT_CODEL)) == NULL)
return (EBADF);
if (*nbytes < sizeof(stats))
return (EINVAL);
stats = cif->cl_stats;
stats.stats = cif->codel.stats;
if ((error = copyout((caddr_t)&stats, ubuf, sizeof(stats))) != 0)
return (error);
*nbytes = sizeof(stats);
return (0);
}
static int
codel_request(struct ifaltq *ifq, int req, void *arg)
{
struct codel_if *cif = (struct codel_if *)ifq->altq_disc;
struct mbuf *m;
IFQ_LOCK_ASSERT(ifq);
switch (req) {
case ALTRQ_PURGE:
if (!ALTQ_IS_ENABLED(cif->cif_ifq))
break;
if (qempty(cif->cl_q))
break;
while ((m = _getq(cif->cl_q)) != NULL) {
PKTCNTR_ADD(&cif->cl_stats.cl_dropcnt, m_pktlen(m));
m_freem(m);
IFQ_DEC_LEN(cif->cif_ifq);
}
cif->cif_ifq->ifq_len = 0;
break;
}
return (0);
}
static int
codel_enqueue(struct ifaltq *ifq, struct mbuf *m, struct altq_pktattr *pktattr)
{
struct codel_if *cif = (struct codel_if *) ifq->altq_disc;
IFQ_LOCK_ASSERT(ifq);
/* grab class set by classifier */
if ((m->m_flags & M_PKTHDR) == 0) {
/* should not happen */
printf("altq: packet for %s does not have pkthdr\n",
ifq->altq_ifp->if_xname);
m_freem(m);
PKTCNTR_ADD(&cif->cl_stats.cl_dropcnt, m_pktlen(m));
return (ENOBUFS);
}
if (codel_addq(&cif->codel, cif->cl_q, m)) {
PKTCNTR_ADD(&cif->cl_stats.cl_dropcnt, m_pktlen(m));
return (ENOBUFS);
}
IFQ_INC_LEN(ifq);
return (0);
}
static struct mbuf *
codel_dequeue(struct ifaltq *ifq, int op)
{
struct codel_if *cif = (struct codel_if *)ifq->altq_disc;
struct mbuf *m;
IFQ_LOCK_ASSERT(ifq);
if (IFQ_IS_EMPTY(ifq))
return (NULL);
if (op == ALTDQ_POLL)
return (qhead(cif->cl_q));
m = codel_getq(&cif->codel, cif->cl_q);
if (m != NULL) {
IFQ_DEC_LEN(ifq);
PKTCNTR_ADD(&cif->cl_stats.cl_xmitcnt, m_pktlen(m));
return (m);
}
return (NULL);
}
struct codel *
codel_alloc(int target, int interval, int ecn)
{
struct codel *c;
c = malloc(sizeof(*c), M_DEVBUF, M_NOWAIT | M_ZERO);
if (c != NULL) {
c->params.target = machclk_freq * target / 1000;
c->params.interval = machclk_freq * interval / 1000;
c->params.ecn = ecn;
c->stats.maxpacket = 256;
}
return (c);
}
void
codel_destroy(struct codel *c)
{
free(c, M_DEVBUF);
}
#define MTAG_CODEL 1438031249
int
codel_addq(struct codel *c, class_queue_t *q, struct mbuf *m)
{
struct m_tag *mtag;
uint64_t *enqueue_time;
if (qlen(q) < qlimit(q)) {
mtag = m_tag_locate(m, MTAG_CODEL, 0, NULL);
if (mtag == NULL) {
mtag = m_tag_alloc(MTAG_CODEL, 0, sizeof(uint64_t),
M_NOWAIT);
if (mtag != NULL)
m_tag_prepend(m, mtag);
}
if (mtag == NULL) {
m_freem(m);
return (-1);
}
enqueue_time = (uint64_t *)(mtag + 1);
*enqueue_time = read_machclk();
_addq(q, m);
return (0);
}
c->drop_overlimit++;
m_freem(m);
return (-1);
}
static int
codel_should_drop(struct codel *c, class_queue_t *q, struct mbuf *m,
u_int64_t now)
{
struct m_tag *mtag;
uint64_t *enqueue_time;
if (m == NULL) {
c->vars.first_above_time = 0;
return (0);
}
mtag = m_tag_locate(m, MTAG_CODEL, 0, NULL);
if (mtag == NULL) {
/* Only one warning per second. */
if (ppsratecheck(&c->last_log, &c->last_pps, 1))
printf("%s: could not found the packet mtag!\n",
__func__);
c->vars.first_above_time = 0;
return (0);
}
enqueue_time = (uint64_t *)(mtag + 1);
c->vars.ldelay = now - *enqueue_time;
c->stats.maxpacket = MAX(c->stats.maxpacket, m_pktlen(m));
if (codel_time_before(c->vars.ldelay, c->params.target) ||
qsize(q) <= c->stats.maxpacket) {
/* went below - stay below for at least interval */
c->vars.first_above_time = 0;
return (0);
}
if (c->vars.first_above_time == 0) {
/* just went above from below. If we stay above
* for at least interval we'll say it's ok to drop
*/
c->vars.first_above_time = now + c->params.interval;
return (0);
}
if (codel_time_after(now, c->vars.first_above_time))
return (1);
return (0);
}
/*
* Run a Newton method step:
* new_invsqrt = (invsqrt / 2) * (3 - count * invsqrt^2)
*
* Here, invsqrt is a fixed point number (< 1.0), 32bit mantissa, aka Q0.32
*/
static void
codel_Newton_step(struct codel_vars *vars)
{
uint32_t invsqrt, invsqrt2;
uint64_t val;
/* sizeof_in_bits(rec_inv_sqrt) */
#define REC_INV_SQRT_BITS (8 * sizeof(u_int16_t))
/* needed shift to get a Q0.32 number from rec_inv_sqrt */
#define REC_INV_SQRT_SHIFT (32 - REC_INV_SQRT_BITS)
invsqrt = ((u_int32_t)vars->rec_inv_sqrt) << REC_INV_SQRT_SHIFT;
invsqrt2 = ((u_int64_t)invsqrt * invsqrt) >> 32;
val = (3LL << 32) - ((u_int64_t)vars->count * invsqrt2);
val >>= 2; /* avoid overflow in following multiply */
val = (val * invsqrt) >> (32 - 2 + 1);
vars->rec_inv_sqrt = val >> REC_INV_SQRT_SHIFT;
}
static u_int64_t
codel_control_law(u_int64_t t, u_int64_t interval, u_int32_t rec_inv_sqrt)
{
return (t + (u_int32_t)(((u_int64_t)interval *
(rec_inv_sqrt << REC_INV_SQRT_SHIFT)) >> 32));
}
struct mbuf *
codel_getq(struct codel *c, class_queue_t *q)
{
struct mbuf *m;
u_int64_t now;
int drop;
if ((m = _getq(q)) == NULL) {
c->vars.dropping = 0;
return (m);
}
now = read_machclk();
drop = codel_should_drop(c, q, m, now);
if (c->vars.dropping) {
if (!drop) {
/* sojourn time below target - leave dropping state */
c->vars.dropping = 0;
} else if (codel_time_after_eq(now, c->vars.drop_next)) {
/* It's time for the next drop. Drop the current
* packet and dequeue the next. The dequeue might
* take us out of dropping state.
* If not, schedule the next drop.
* A large backlog might result in drop rates so high
* that the next drop should happen now,
* hence the while loop.
*/
while (c->vars.dropping &&
codel_time_after_eq(now, c->vars.drop_next)) {
c->vars.count++; /* don't care of possible wrap
* since there is no more
* divide */
codel_Newton_step(&c->vars);
/* TODO ECN */
PKTCNTR_ADD(&c->stats.drop_cnt, m_pktlen(m));
m_freem(m);
m = _getq(q);
if (!codel_should_drop(c, q, m, now))
/* leave dropping state */
c->vars.dropping = 0;
else
/* and schedule the next drop */
c->vars.drop_next =
codel_control_law(c->vars.drop_next,
c->params.interval,
c->vars.rec_inv_sqrt);
}
}
} else if (drop) {
/* TODO ECN */
PKTCNTR_ADD(&c->stats.drop_cnt, m_pktlen(m));
m_freem(m);
m = _getq(q);
drop = codel_should_drop(c, q, m, now);
c->vars.dropping = 1;
/* if min went above target close to when we last went below it
* assume that the drop rate that controlled the queue on the
* last cycle is a good starting point to control it now.
*/
if (codel_time_before(now - c->vars.drop_next,
16 * c->params.interval)) {
c->vars.count = (c->vars.count - c->vars.lastcount) | 1;
/* we dont care if rec_inv_sqrt approximation
* is not very precise :
* Next Newton steps will correct it quadratically.
*/
codel_Newton_step(&c->vars);
} else {
c->vars.count = 1;
c->vars.rec_inv_sqrt = ~0U >> REC_INV_SQRT_SHIFT;
}
c->vars.lastcount = c->vars.count;
c->vars.drop_next = codel_control_law(now, c->params.interval,
c->vars.rec_inv_sqrt);
}
return (m);
}
void
codel_getstats(struct codel *c, struct codel_stats *s)
{
*s = c->stats;
}
#endif /* ALTQ_CODEL */
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