/* CoDel ECN marking. Borrow from codel_dequeue in Linux kernel */
static void codel_marking(struct sk_buff *skb, struct wfq_class *cl)
{
s64 now_ns = ktime_get_ns();
codel_time_t now = ns_to_codel_time(now_ns);
bool mark = codel_should_mark(skb, cl, now_ns);
if (cl->marking)
{
if (!mark)
{
/* sojourn time below target - leave marking state */
cl->marking = false;
}
else if (codel_time_after_eq(now, cl->mark_next))
{
/* It's time for the next mark */
cl->count++;
codel_Newton_step(cl);
cl->mark_next = codel_control_law(cl->mark_next,
wfq_codel_interval,
cl->rec_inv_sqrt);
INET_ECN_set_ce(skb);
}
}
else if (mark)
{
u32 delta;
INET_ECN_set_ce(skb);
cl->marking = true;
/* 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.
*/
delta = cl->count - cl->lastcount;
if (delta > 1 &&
codel_time_before(now - cl->mark_next,
(codel_time_t)wfq_codel_interval * 16))
{
cl->count = delta;
/* we dont care if rec_inv_sqrt approximation
* is not very precise :
* Next Newton steps will correct it quadratically.
*/
codel_Newton_step(cl);
}
else
{
cl->count = 1;
cl->rec_inv_sqrt = ~0U >> REC_INV_SQRT_SHIFT;
}
cl->lastcount = cl->count;
cl->mark_next = codel_control_law(now,
wfq_codel_interval,
cl->rec_inv_sqrt);
}
}
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);
}
