diff options
Diffstat (limited to 'net/sched/sch_pie.c')
| -rw-r--r-- | net/sched/sch_pie.c | 289 |
1 files changed, 104 insertions, 185 deletions
diff --git a/net/sched/sch_pie.c b/net/sched/sch_pie.c index b0b0dc46af61..915bcdb59a9f 100644 --- a/net/sched/sch_pie.c +++ b/net/sched/sch_pie.c @@ -19,159 +19,76 @@ #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) @@ -184,7 +101,8 @@ static int pie_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch, 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)) { @@ -216,14 +134,14 @@ out: } 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, @@ -296,26 +214,25 @@ 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; @@ -327,39 +244,39 @@ static void pie_process_dequeue(struct Qdisc *sch, struct sk_buff *skb) * 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 @@ -367,10 +284,10 @@ static void pie_process_dequeue(struct Qdisc *sch, struct sk_buff *skb) * 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; @@ -380,18 +297,18 @@ static void pie_process_dequeue(struct Qdisc *sch, struct sk_buff *skb) 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 */ @@ -400,21 +317,21 @@ static void calculate_probability(struct Qdisc *sch) 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; @@ -426,18 +343,18 @@ static void calculate_probability(struct Qdisc *sch) * 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; @@ -446,14 +363,14 @@ static void calculate_probability(struct Qdisc *sch) } /* 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: @@ -464,12 +381,12 @@ static void calculate_probability(struct Qdisc *sch) 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 @@ -479,8 +396,8 @@ static void calculate_probability(struct Qdisc *sch) } } 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 @@ -489,10 +406,10 @@ static void calculate_probability(struct Qdisc *sch) 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 @@ -500,16 +417,17 @@ static void calculate_probability(struct Qdisc *sch) * 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) { @@ -518,7 +436,7 @@ 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) @@ -607,12 +525,13 @@ static int pie_dump_stats(struct Qdisc *sch, struct gnet_dump *d) 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; } @@ -633,7 +552,7 @@ static void pie_destroy(struct Qdisc *sch) } 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, |