#include <linux/skbuff.h>
#include <net/pkt_sched.h>
#include <net/inet_ecn.h>
-
-#define QUEUE_THRESHOLD 16384
-#define DQCOUNT_INVALID -1
-#define DTIME_INVALID 0xffffffffffffffff
-#define MAX_PROB 0xffffffffffffffff
-#define PIE_SCALE 8
-
-/* parameters used */
-struct pie_params {
- psched_time_t target; /* user specified target delay in pschedtime */
- u32 tupdate; /* timer frequency (in jiffies) */
- u32 limit; /* number of packets that can be enqueued */
- u32 alpha; /* alpha and beta are between 0 and 32 */
- 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 */
-struct pie_vars {
- u64 prob; /* probability but scaled by u64 limit. */
- psched_time_t burst_time;
- psched_time_t qdelay;
- psched_time_t qdelay_old;
- u64 dq_count; /* measured in bytes */
- psched_time_t dq_tstamp; /* drain rate */
- u64 accu_prob; /* accumulated drop probability */
- u32 avg_dq_rate; /* bytes per pschedtime tick,scaled */
- u32 qlen_old; /* in bytes */
- u8 accu_prob_overflows; /* overflows of accu_prob */
-};
-
-/* statistics gathering */
-struct pie_stats {
- 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 */
-};
+#include <net/pie.h>
/* private data for the Qdisc */
struct pie_sched_data {
- struct pie_params params;
struct pie_vars vars;
+ struct pie_params params;
struct pie_stats stats;
struct timer_list adapt_timer;
struct Qdisc *sch;
};
-static void pie_params_init(struct pie_params *params)
+bool pie_drop_early(struct Qdisc *sch, struct pie_params *params,
+ struct pie_vars *vars, u32 qlen, u32 packet_size)
{
- params->alpha = 2;
- params->beta = 20;
- params->tupdate = usecs_to_jiffies(15 * USEC_PER_MSEC); /* 15 ms */
- params->limit = 1000; /* default of 1000 packets */
- 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 */
- vars->burst_time = PSCHED_NS2TICKS(150 * NSEC_PER_MSEC);
- vars->accu_prob_overflows = 0;
-}
-
-static bool drop_early(struct Qdisc *sch, u32 packet_size)
-{
- struct pie_sched_data *q = qdisc_priv(sch);
u64 rnd;
- u64 local_prob = q->vars.prob;
+ u64 local_prob = vars->prob;
u32 mtu = psched_mtu(qdisc_dev(sch));
/* If there is still burst allowance left skip random early drop */
- if (q->vars.burst_time > 0)
+ if (vars->burst_time > 0)
return false;
/* If current delay is less than half of target, and
* if drop prob is low already, disable early_drop
*/
- if ((q->vars.qdelay < q->params.target / 2) &&
- (q->vars.prob < MAX_PROB / 5))
+ if ((vars->qdelay < params->target / 2) &&
+ (vars->prob < MAX_PROB / 5))
return false;
- /* If we have fewer than 2 mtu-sized packets, disable drop_early,
+ /* If we have fewer than 2 mtu-sized packets, disable pie_drop_early,
* similar to min_th in RED
*/
- if (sch->qstats.backlog < 2 * mtu)
+ if (qlen < 2 * mtu)
return false;
/* If bytemode is turned on, use packet size to compute new
* probablity. Smaller packets will have lower drop prob in this case
*/
- if (q->params.bytemode && packet_size <= mtu)
+ if (params->bytemode && packet_size <= mtu)
local_prob = (u64)packet_size * div_u64(local_prob, mtu);
else
- local_prob = q->vars.prob;
+ local_prob = vars->prob;
if (local_prob == 0) {
- q->vars.accu_prob = 0;
- q->vars.accu_prob_overflows = 0;
+ vars->accu_prob = 0;
+ vars->accu_prob_overflows = 0;
}
- if (local_prob > MAX_PROB - q->vars.accu_prob)
- q->vars.accu_prob_overflows++;
+ if (local_prob > MAX_PROB - vars->accu_prob)
+ vars->accu_prob_overflows++;
- q->vars.accu_prob += local_prob;
+ vars->accu_prob += local_prob;
- if (q->vars.accu_prob_overflows == 0 &&
- q->vars.accu_prob < (MAX_PROB / 100) * 85)
+ if (vars->accu_prob_overflows == 0 &&
+ vars->accu_prob < (MAX_PROB / 100) * 85)
return false;
- if (q->vars.accu_prob_overflows == 8 &&
- q->vars.accu_prob >= MAX_PROB / 2)
+ if (vars->accu_prob_overflows == 8 &&
+ vars->accu_prob >= MAX_PROB / 2)
return true;
prandom_bytes(&rnd, 8);
if (rnd < local_prob) {
- q->vars.accu_prob = 0;
- q->vars.accu_prob_overflows = 0;
+ vars->accu_prob = 0;
+ vars->accu_prob_overflows = 0;
return true;
}
return false;
}
+EXPORT_SYMBOL_GPL(pie_drop_early);
static int pie_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
goto out;
}
- if (!drop_early(sch, skb->len)) {
+ if (!pie_drop_early(sch, &q->params, &q->vars, sch->qstats.backlog,
+ skb->len)) {
enqueue = true;
} else if (q->params.ecn && (q->vars.prob <= MAX_PROB / 10) &&
INET_ECN_set_ce(skb)) {
}
static const struct nla_policy pie_policy[TCA_PIE_MAX + 1] = {
- [TCA_PIE_TARGET] = {.type = NLA_U32},
- [TCA_PIE_LIMIT] = {.type = NLA_U32},
- [TCA_PIE_TUPDATE] = {.type = NLA_U32},
- [TCA_PIE_ALPHA] = {.type = NLA_U32},
- [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},
+ [TCA_PIE_TARGET] = {.type = NLA_U32},
+ [TCA_PIE_LIMIT] = {.type = NLA_U32},
+ [TCA_PIE_TUPDATE] = {.type = NLA_U32},
+ [TCA_PIE_ALPHA] = {.type = NLA_U32},
+ [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,
return 0;
}
-static void pie_process_dequeue(struct Qdisc *sch, struct sk_buff *skb)
+void pie_process_dequeue(struct sk_buff *skb, struct pie_params *params,
+ struct pie_vars *vars, u32 qlen)
{
- 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 (!params->dq_rate_estimator) {
+ vars->qdelay = now - pie_get_enqueue_time(skb);
- if (q->vars.dq_tstamp != DTIME_INVALID)
- dtime = now - q->vars.dq_tstamp;
+ if (vars->dq_tstamp != DTIME_INVALID)
+ dtime = now - vars->dq_tstamp;
- q->vars.dq_tstamp = now;
+ vars->dq_tstamp = now;
if (qlen == 0)
- q->vars.qdelay = 0;
+ vars->qdelay = 0;
if (dtime == 0)
return;
* we have enough packets to calculate the drain rate. Save
* current time as dq_tstamp and start measurement cycle.
*/
- if (qlen >= QUEUE_THRESHOLD && q->vars.dq_count == DQCOUNT_INVALID) {
- q->vars.dq_tstamp = psched_get_time();
- q->vars.dq_count = 0;
+ if (qlen >= QUEUE_THRESHOLD && vars->dq_count == DQCOUNT_INVALID) {
+ vars->dq_tstamp = psched_get_time();
+ vars->dq_count = 0;
}
- /* Calculate the average drain rate from this value. If queue length
- * has receded to a small value viz., <= QUEUE_THRESHOLD bytes,reset
+ /* Calculate the average drain rate from this value. If queue length
+ * has receded to a small value viz., <= QUEUE_THRESHOLD bytes, reset
* the dq_count to -1 as we don't have enough packets to calculate the
- * drain rate anymore The following if block is entered only when we
+ * drain rate anymore. The following if block is entered only when we
* have a substantial queue built up (QUEUE_THRESHOLD bytes or more)
* and we calculate the drain rate for the threshold here. dq_count is
* in bytes, time difference in psched_time, hence rate is in
* bytes/psched_time.
*/
- if (q->vars.dq_count != DQCOUNT_INVALID) {
- q->vars.dq_count += skb->len;
+ if (vars->dq_count != DQCOUNT_INVALID) {
+ vars->dq_count += skb->len;
- if (q->vars.dq_count >= QUEUE_THRESHOLD) {
- u32 count = q->vars.dq_count << PIE_SCALE;
+ if (vars->dq_count >= QUEUE_THRESHOLD) {
+ u32 count = vars->dq_count << PIE_SCALE;
- dtime = now - q->vars.dq_tstamp;
+ dtime = now - vars->dq_tstamp;
if (dtime == 0)
return;
count = count / dtime;
- if (q->vars.avg_dq_rate == 0)
- q->vars.avg_dq_rate = count;
+ if (vars->avg_dq_rate == 0)
+ vars->avg_dq_rate = count;
else
- q->vars.avg_dq_rate =
- (q->vars.avg_dq_rate -
- (q->vars.avg_dq_rate >> 3)) + (count >> 3);
+ vars->avg_dq_rate =
+ (vars->avg_dq_rate -
+ (vars->avg_dq_rate >> 3)) + (count >> 3);
/* If the queue has receded below the threshold, we hold
* on to the last drain rate calculated, else we reset
* packet is dequeued
*/
if (qlen < QUEUE_THRESHOLD) {
- q->vars.dq_count = DQCOUNT_INVALID;
+ vars->dq_count = DQCOUNT_INVALID;
} else {
- q->vars.dq_count = 0;
- q->vars.dq_tstamp = psched_get_time();
+ vars->dq_count = 0;
+ vars->dq_tstamp = psched_get_time();
}
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;
+ if (vars->burst_time > 0) {
+ if (vars->burst_time > dtime)
+ vars->burst_time -= dtime;
else
- q->vars.burst_time = 0;
+ vars->burst_time = 0;
}
}
+EXPORT_SYMBOL_GPL(pie_process_dequeue);
-static void calculate_probability(struct Qdisc *sch)
+void pie_calculate_probability(struct pie_params *params, struct pie_vars *vars,
+ u32 qlen)
{
- 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 = 0; /* in pschedtime */
s64 delta = 0; /* determines the change in probability */
u32 power;
bool update_prob = true;
- if (q->params.dq_rate_estimator) {
- qdelay_old = q->vars.qdelay;
- q->vars.qdelay_old = q->vars.qdelay;
+ if (params->dq_rate_estimator) {
+ qdelay_old = vars->qdelay;
+ vars->qdelay_old = vars->qdelay;
- if (q->vars.avg_dq_rate > 0)
- qdelay = (qlen << PIE_SCALE) / q->vars.avg_dq_rate;
+ if (vars->avg_dq_rate > 0)
+ qdelay = (qlen << PIE_SCALE) / vars->avg_dq_rate;
else
qdelay = 0;
} else {
- qdelay = q->vars.qdelay;
- qdelay_old = q->vars.qdelay_old;
+ qdelay = vars->qdelay;
+ qdelay_old = 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
+ /* If qdelay is zero and qlen is not, it means qlen is very small,
+ * so we do not update probabilty in this round.
*/
if (qdelay == 0 && qlen != 0)
update_prob = false;
* probability. alpha/beta are updated locally below by scaling down
* by 16 to come to 0-2 range.
*/
- alpha = ((u64)q->params.alpha * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 4;
- beta = ((u64)q->params.beta * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 4;
+ alpha = ((u64)params->alpha * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 4;
+ beta = ((u64)params->beta * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 4;
/* We scale alpha and beta differently depending on how heavy the
* congestion is. Please see RFC 8033 for details.
*/
- if (q->vars.prob < MAX_PROB / 10) {
+ if (vars->prob < MAX_PROB / 10) {
alpha >>= 1;
beta >>= 1;
power = 100;
- while (q->vars.prob < div_u64(MAX_PROB, power) &&
+ while (vars->prob < div_u64(MAX_PROB, power) &&
power <= 1000000) {
alpha >>= 2;
beta >>= 2;
}
/* alpha and beta should be between 0 and 32, in multiples of 1/16 */
- delta += alpha * (u64)(qdelay - q->params.target);
+ delta += alpha * (u64)(qdelay - params->target);
delta += beta * (u64)(qdelay - qdelay_old);
- oldprob = q->vars.prob;
+ oldprob = vars->prob;
/* to ensure we increase probability in steps of no more than 2% */
if (delta > (s64)(MAX_PROB / (100 / 2)) &&
- q->vars.prob >= MAX_PROB / 10)
+ vars->prob >= MAX_PROB / 10)
delta = (MAX_PROB / 100) * 2;
/* Non-linear drop:
if (qdelay > (PSCHED_NS2TICKS(250 * NSEC_PER_MSEC)))
delta += MAX_PROB / (100 / 2);
- q->vars.prob += delta;
+ vars->prob += delta;
if (delta > 0) {
/* prevent overflow */
- if (q->vars.prob < oldprob) {
- q->vars.prob = MAX_PROB;
+ if (vars->prob < oldprob) {
+ vars->prob = MAX_PROB;
/* Prevent normalization error. If probability is at
* maximum value already, we normalize it here, and
* skip the check to do a non-linear drop in the next
}
} else {
/* prevent underflow */
- if (q->vars.prob > oldprob)
- q->vars.prob = 0;
+ if (vars->prob > oldprob)
+ vars->prob = 0;
}
/* Non-linear drop in probability: Reduce drop probability quickly if
if (qdelay == 0 && qdelay_old == 0 && update_prob)
/* Reduce drop probability to 98.4% */
- q->vars.prob -= q->vars.prob / 64u;
+ vars->prob -= vars->prob / 64;
- q->vars.qdelay = qdelay;
- q->vars.qlen_old = qlen;
+ vars->qdelay = qdelay;
+ vars->qlen_old = qlen;
/* We restart the measurement cycle if the following conditions are met
* 1. If the delay has been low for 2 consecutive Tupdate periods
* 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->params.dq_rate_estimator || q->vars.avg_dq_rate > 0)) {
- pie_vars_init(&q->vars);
+ if ((vars->qdelay < params->target / 2) &&
+ (vars->qdelay_old < params->target / 2) &&
+ vars->prob == 0 &&
+ (!params->dq_rate_estimator || vars->avg_dq_rate > 0)) {
+ pie_vars_init(vars);
}
- if (!q->params.dq_rate_estimator)
- q->vars.qdelay_old = qdelay;
+ if (!params->dq_rate_estimator)
+ vars->qdelay_old = qdelay;
}
+EXPORT_SYMBOL_GPL(pie_calculate_probability);
static void pie_timer(struct timer_list *t)
{
spinlock_t *root_lock = qdisc_lock(qdisc_root_sleeping(sch));
spin_lock(root_lock);
- calculate_probability(sch);
+ pie_calculate_probability(&q->params, &q->vars, sch->qstats.backlog);
/* reset the timer to fire after 'tupdate'. tupdate is in jiffies. */
if (q->params.tupdate)
static struct sk_buff *pie_qdisc_dequeue(struct Qdisc *sch)
{
+ struct pie_sched_data *q = qdisc_priv(sch);
struct sk_buff *skb = qdisc_dequeue_head(sch);
if (!skb)
return NULL;
- pie_process_dequeue(sch, skb);
+ pie_process_dequeue(skb, &q->params, &q->vars, sch->qstats.backlog);
return skb;
}
}
static struct Qdisc_ops pie_qdisc_ops __read_mostly = {
- .id = "pie",
+ .id = "pie",
.priv_size = sizeof(struct pie_sched_data),
.enqueue = pie_qdisc_enqueue,
.dequeue = pie_qdisc_dequeue,
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