@@ -950,19 +950,25 @@ enum {
TCA_PIE_BETA,
TCA_PIE_ECN,
TCA_PIE_BYTEMODE,
+ TCA_PIE_DQ_RATE_ESTIMATOR,
__TCA_PIE_MAX
};
#define TCA_PIE_MAX (__TCA_PIE_MAX - 1)
struct tc_pie_xstats {
- __u64 prob; /* current probability */
- __u32 delay; /* current delay in ms */
- __u32 avg_dq_rate; /* current average dq_rate in bits/pie_time */
- __u32 packets_in; /* total number of packets enqueued */
- __u32 dropped; /* packets dropped due to pie_action */
- __u32 overlimit; /* dropped due to lack of space in queue */
- __u32 maxq; /* maximum queue size */
- __u32 ecn_mark; /* packets marked with ecn*/
+ __u64 prob; /* current probability */
+ __u32 delay; /* current delay in ms */
+ __u32 avg_dq_rate; /* current average dq_rate in
+ * bits/pie_time
+ */
+ __u32 dq_rate_estimating; /* is avg_dq_rate being calculated? */
+ __u32 packets_in; /* total number of packets enqueued */
+ __u32 dropped; /* packets dropped due to pie_action */
+ __u32 overlimit; /* dropped due to lack of space
+ * in queue
+ */
+ __u32 maxq; /* maximum queue size */
+ __u32 ecn_mark; /* packets marked with ecn*/
};
/* CBS */
@@ -22,6 +22,7 @@
#define QUEUE_THRESHOLD 16384
#define DQCOUNT_INVALID -1
+#define DTIME_INVALID 0xffffffffffffffff
#define MAX_PROB 0xffffffffffffffff
#define PIE_SCALE 8
@@ -34,6 +35,7 @@ struct pie_params {
u32 beta; /* and are used for shift relative to 1 */
bool ecn; /* true if ecn is enabled */
bool bytemode; /* to scale drop early prob based on pkt size */
+ u8 dq_rate_estimator; /* to calculate delay using Little's law */
};
/* variables used */
@@ -77,11 +79,34 @@ static void pie_params_init(struct pie_params *params)
params->target = PSCHED_NS2TICKS(15 * NSEC_PER_MSEC); /* 15 ms */
params->ecn = false;
params->bytemode = false;
+ params->dq_rate_estimator = false;
+}
+
+/* private skb vars */
+struct pie_skb_cb {
+ psched_time_t enqueue_time;
+};
+
+static struct pie_skb_cb *get_pie_cb(const struct sk_buff *skb)
+{
+ qdisc_cb_private_validate(skb, sizeof(struct pie_skb_cb));
+ return (struct pie_skb_cb *)qdisc_skb_cb(skb)->data;
+}
+
+static psched_time_t pie_get_enqueue_time(const struct sk_buff *skb)
+{
+ return get_pie_cb(skb)->enqueue_time;
+}
+
+static void pie_set_enqueue_time(struct sk_buff *skb)
+{
+ get_pie_cb(skb)->enqueue_time = psched_get_time();
}
static void pie_vars_init(struct pie_vars *vars)
{
vars->dq_count = DQCOUNT_INVALID;
+ vars->dq_tstamp = DTIME_INVALID;
vars->accu_prob = 0;
vars->avg_dq_rate = 0;
/* default of 150 ms in pschedtime */
@@ -172,6 +197,10 @@ static int pie_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch,
/* we can enqueue the packet */
if (enqueue) {
+ /* Set enqueue time only when dq_rate_estimator is disabled. */
+ if (!q->params.dq_rate_estimator)
+ pie_set_enqueue_time(skb);
+
q->stats.packets_in++;
if (qdisc_qlen(sch) > q->stats.maxq)
q->stats.maxq = qdisc_qlen(sch);
@@ -194,6 +223,7 @@ static const struct nla_policy pie_policy[TCA_PIE_MAX + 1] = {
[TCA_PIE_BETA] = {.type = NLA_U32},
[TCA_PIE_ECN] = {.type = NLA_U32},
[TCA_PIE_BYTEMODE] = {.type = NLA_U32},
+ [TCA_PIE_DQ_RATE_ESTIMATOR] = {.type = NLA_U32},
};
static int pie_change(struct Qdisc *sch, struct nlattr *opt,
@@ -247,6 +277,10 @@ static int pie_change(struct Qdisc *sch, struct nlattr *opt,
if (tb[TCA_PIE_BYTEMODE])
q->params.bytemode = nla_get_u32(tb[TCA_PIE_BYTEMODE]);
+ if (tb[TCA_PIE_DQ_RATE_ESTIMATOR])
+ q->params.dq_rate_estimator =
+ nla_get_u32(tb[TCA_PIE_DQ_RATE_ESTIMATOR]);
+
/* Drop excess packets if new limit is lower */
qlen = sch->q.qlen;
while (sch->q.qlen > sch->limit) {
@@ -266,6 +300,28 @@ static void pie_process_dequeue(struct Qdisc *sch, struct sk_buff *skb)
{
struct pie_sched_data *q = qdisc_priv(sch);
int qlen = sch->qstats.backlog; /* current queue size in bytes */
+ psched_time_t now = psched_get_time();
+ u32 dtime = 0;
+
+ /* If dq_rate_estimator is disabled, calculate qdelay using the
+ * packet timestamp.
+ */
+ if (!q->params.dq_rate_estimator) {
+ q->vars.qdelay = now - pie_get_enqueue_time(skb);
+
+ if (q->vars.dq_tstamp != DTIME_INVALID)
+ dtime = now - q->vars.dq_tstamp;
+
+ q->vars.dq_tstamp = now;
+
+ if (qlen == 0)
+ q->vars.qdelay = 0;
+
+ if (dtime == 0)
+ return;
+
+ goto burst_allowance_reduction;
+ }
/* If current queue is about 10 packets or more and dq_count is unset
* we have enough packets to calculate the drain rate. Save
@@ -289,10 +345,10 @@ static void pie_process_dequeue(struct Qdisc *sch, struct sk_buff *skb)
q->vars.dq_count += skb->len;
if (q->vars.dq_count >= QUEUE_THRESHOLD) {
- psched_time_t now = psched_get_time();
- u32 dtime = now - q->vars.dq_tstamp;
u32 count = q->vars.dq_count << PIE_SCALE;
+ dtime = now - q->vars.dq_tstamp;
+
if (dtime == 0)
return;
@@ -317,14 +373,19 @@ static void pie_process_dequeue(struct Qdisc *sch, struct sk_buff *skb)
q->vars.dq_tstamp = psched_get_time();
}
- if (q->vars.burst_time > 0) {
- if (q->vars.burst_time > dtime)
- q->vars.burst_time -= dtime;
- else
- q->vars.burst_time = 0;
- }
+ goto burst_allowance_reduction;
}
}
+
+ return;
+
+burst_allowance_reduction:
+ if (q->vars.burst_time > 0) {
+ if (q->vars.burst_time > dtime)
+ q->vars.burst_time -= dtime;
+ else
+ q->vars.burst_time = 0;
+ }
}
static void calculate_probability(struct Qdisc *sch)
@@ -332,19 +393,25 @@ static void calculate_probability(struct Qdisc *sch)
struct pie_sched_data *q = qdisc_priv(sch);
u32 qlen = sch->qstats.backlog; /* queue size in bytes */
psched_time_t qdelay = 0; /* in pschedtime */
- psched_time_t qdelay_old = q->vars.qdelay; /* in pschedtime */
+ psched_time_t qdelay_old = 0; /* in pschedtime */
s64 delta = 0; /* determines the change in probability */
u64 oldprob;
u64 alpha, beta;
u32 power;
bool update_prob = true;
- q->vars.qdelay_old = q->vars.qdelay;
+ if (q->params.dq_rate_estimator) {
+ qdelay_old = q->vars.qdelay;
+ q->vars.qdelay_old = q->vars.qdelay;
- if (q->vars.avg_dq_rate > 0)
- qdelay = (qlen << PIE_SCALE) / q->vars.avg_dq_rate;
- else
- qdelay = 0;
+ if (q->vars.avg_dq_rate > 0)
+ qdelay = (qlen << PIE_SCALE) / q->vars.avg_dq_rate;
+ else
+ qdelay = 0;
+ } else {
+ qdelay = q->vars.qdelay;
+ qdelay_old = q->vars.qdelay_old;
+ }
/* If qdelay is zero and qlen is not, it means qlen is very small, less
* than dequeue_rate, so we do not update probabilty in this round
@@ -430,14 +497,18 @@ static void calculate_probability(struct Qdisc *sch)
/* We restart the measurement cycle if the following conditions are met
* 1. If the delay has been low for 2 consecutive Tupdate periods
* 2. Calculated drop probability is zero
- * 3. We have atleast one estimate for the avg_dq_rate ie.,
- * is a non-zero value
+ * 3. If average dq_rate_estimator is enabled, we have atleast one
+ * estimate for the avg_dq_rate ie., is a non-zero value
*/
if ((q->vars.qdelay < q->params.target / 2) &&
(q->vars.qdelay_old < q->params.target / 2) &&
q->vars.prob == 0 &&
- q->vars.avg_dq_rate > 0)
+ (!q->params.dq_rate_estimator || q->vars.avg_dq_rate > 0)) {
pie_vars_init(&q->vars);
+ }
+
+ if (!q->params.dq_rate_estimator)
+ q->vars.qdelay_old = qdelay;
}
static void pie_timer(struct timer_list *t)
@@ -497,7 +568,9 @@ static int pie_dump(struct Qdisc *sch, struct sk_buff *skb)
nla_put_u32(skb, TCA_PIE_ALPHA, q->params.alpha) ||
nla_put_u32(skb, TCA_PIE_BETA, q->params.beta) ||
nla_put_u32(skb, TCA_PIE_ECN, q->params.ecn) ||
- nla_put_u32(skb, TCA_PIE_BYTEMODE, q->params.bytemode))
+ nla_put_u32(skb, TCA_PIE_BYTEMODE, q->params.bytemode) ||
+ nla_put_u32(skb, TCA_PIE_DQ_RATE_ESTIMATOR,
+ q->params.dq_rate_estimator))
goto nla_put_failure;
return nla_nest_end(skb, opts);
@@ -514,9 +587,6 @@ static int pie_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
.prob = q->vars.prob,
.delay = ((u32)PSCHED_TICKS2NS(q->vars.qdelay)) /
NSEC_PER_USEC,
- /* unscale and return dq_rate in bytes per sec */
- .avg_dq_rate = q->vars.avg_dq_rate *
- (PSCHED_TICKS_PER_SEC) >> PIE_SCALE,
.packets_in = q->stats.packets_in,
.overlimit = q->stats.overlimit,
.maxq = q->stats.maxq,
@@ -524,6 +594,14 @@ static int pie_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
.ecn_mark = q->stats.ecn_mark,
};
+ /* avg_dq_rate is only valid if dq_rate_estimator is enabled */
+ st.dq_rate_estimating = q->params.dq_rate_estimator;
+
+ /* unscale and return dq_rate in bytes per sec */
+ if (q->params.dq_rate_estimator)
+ st.avg_dq_rate = q->vars.avg_dq_rate *
+ (PSCHED_TICKS_PER_SEC) >> PIE_SCALE;
+
return gnet_stats_copy_app(d, &st, sizeof(st));
}