swh:1:snp:77163734605b0ec556b01d897b7bb4a7e30d46b6
Tip revision: bbf5c979011a099af5dc76498918ed7df445635b authored by Linus Torvalds on 11 October 2020, 21:15:50 UTC
Linux 5.9
Linux 5.9
Tip revision: bbf5c97
sch_fq_pie.c
// SPDX-License-Identifier: GPL-2.0-only
/* Flow Queue PIE discipline
*
* Copyright (C) 2019 Mohit P. Tahiliani <tahiliani@nitk.edu.in>
* Copyright (C) 2019 Sachin D. Patil <sdp.sachin@gmail.com>
* Copyright (C) 2019 V. Saicharan <vsaicharan1998@gmail.com>
* Copyright (C) 2019 Mohit Bhasi <mohitbhasi1998@gmail.com>
* Copyright (C) 2019 Leslie Monis <lesliemonis@gmail.com>
* Copyright (C) 2019 Gautam Ramakrishnan <gautamramk@gmail.com>
*/
#include <linux/jhash.h>
#include <linux/sizes.h>
#include <linux/vmalloc.h>
#include <net/pkt_cls.h>
#include <net/pie.h>
/* Flow Queue PIE
*
* Principles:
* - Packets are classified on flows.
* - This is a Stochastic model (as we use a hash, several flows might
* be hashed to the same slot)
* - Each flow has a PIE managed queue.
* - Flows are linked onto two (Round Robin) lists,
* so that new flows have priority on old ones.
* - For a given flow, packets are not reordered.
* - Drops during enqueue only.
* - ECN capability is off by default.
* - ECN threshold (if ECN is enabled) is at 10% by default.
* - Uses timestamps to calculate queue delay by default.
*/
/**
* struct fq_pie_flow - contains data for each flow
* @vars: pie vars associated with the flow
* @deficit: number of remaining byte credits
* @backlog: size of data in the flow
* @qlen: number of packets in the flow
* @flowchain: flowchain for the flow
* @head: first packet in the flow
* @tail: last packet in the flow
*/
struct fq_pie_flow {
struct pie_vars vars;
s32 deficit;
u32 backlog;
u32 qlen;
struct list_head flowchain;
struct sk_buff *head;
struct sk_buff *tail;
};
struct fq_pie_sched_data {
struct tcf_proto __rcu *filter_list; /* optional external classifier */
struct tcf_block *block;
struct fq_pie_flow *flows;
struct Qdisc *sch;
struct list_head old_flows;
struct list_head new_flows;
struct pie_params p_params;
u32 ecn_prob;
u32 flows_cnt;
u32 quantum;
u32 memory_limit;
u32 new_flow_count;
u32 memory_usage;
u32 overmemory;
struct pie_stats stats;
struct timer_list adapt_timer;
};
static unsigned int fq_pie_hash(const struct fq_pie_sched_data *q,
struct sk_buff *skb)
{
return reciprocal_scale(skb_get_hash(skb), q->flows_cnt);
}
static unsigned int fq_pie_classify(struct sk_buff *skb, struct Qdisc *sch,
int *qerr)
{
struct fq_pie_sched_data *q = qdisc_priv(sch);
struct tcf_proto *filter;
struct tcf_result res;
int result;
if (TC_H_MAJ(skb->priority) == sch->handle &&
TC_H_MIN(skb->priority) > 0 &&
TC_H_MIN(skb->priority) <= q->flows_cnt)
return TC_H_MIN(skb->priority);
filter = rcu_dereference_bh(q->filter_list);
if (!filter)
return fq_pie_hash(q, skb) + 1;
*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
result = tcf_classify(skb, filter, &res, false);
if (result >= 0) {
#ifdef CONFIG_NET_CLS_ACT
switch (result) {
case TC_ACT_STOLEN:
case TC_ACT_QUEUED:
case TC_ACT_TRAP:
*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
fallthrough;
case TC_ACT_SHOT:
return 0;
}
#endif
if (TC_H_MIN(res.classid) <= q->flows_cnt)
return TC_H_MIN(res.classid);
}
return 0;
}
/* add skb to flow queue (tail add) */
static inline void flow_queue_add(struct fq_pie_flow *flow,
struct sk_buff *skb)
{
if (!flow->head)
flow->head = skb;
else
flow->tail->next = skb;
flow->tail = skb;
skb->next = NULL;
}
static int fq_pie_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
struct fq_pie_sched_data *q = qdisc_priv(sch);
struct fq_pie_flow *sel_flow;
int ret;
u8 memory_limited = false;
u8 enqueue = false;
u32 pkt_len;
u32 idx;
/* Classifies packet into corresponding flow */
idx = fq_pie_classify(skb, sch, &ret);
sel_flow = &q->flows[idx];
/* Checks whether adding a new packet would exceed memory limit */
get_pie_cb(skb)->mem_usage = skb->truesize;
memory_limited = q->memory_usage > q->memory_limit + skb->truesize;
/* Checks if the qdisc is full */
if (unlikely(qdisc_qlen(sch) >= sch->limit)) {
q->stats.overlimit++;
goto out;
} else if (unlikely(memory_limited)) {
q->overmemory++;
}
if (!pie_drop_early(sch, &q->p_params, &sel_flow->vars,
sel_flow->backlog, skb->len)) {
enqueue = true;
} else if (q->p_params.ecn &&
sel_flow->vars.prob <= (MAX_PROB / 100) * q->ecn_prob &&
INET_ECN_set_ce(skb)) {
/* If packet is ecn capable, mark it if drop probability
* is lower than the parameter ecn_prob, else drop it.
*/
q->stats.ecn_mark++;
enqueue = true;
}
if (enqueue) {
/* Set enqueue time only when dq_rate_estimator is disabled. */
if (!q->p_params.dq_rate_estimator)
pie_set_enqueue_time(skb);
pkt_len = qdisc_pkt_len(skb);
q->stats.packets_in++;
q->memory_usage += skb->truesize;
sch->qstats.backlog += pkt_len;
sch->q.qlen++;
flow_queue_add(sel_flow, skb);
if (list_empty(&sel_flow->flowchain)) {
list_add_tail(&sel_flow->flowchain, &q->new_flows);
q->new_flow_count++;
sel_flow->deficit = q->quantum;
sel_flow->qlen = 0;
sel_flow->backlog = 0;
}
sel_flow->qlen++;
sel_flow->backlog += pkt_len;
return NET_XMIT_SUCCESS;
}
out:
q->stats.dropped++;
sel_flow->vars.accu_prob = 0;
__qdisc_drop(skb, to_free);
qdisc_qstats_drop(sch);
return NET_XMIT_CN;
}
static const struct nla_policy fq_pie_policy[TCA_FQ_PIE_MAX + 1] = {
[TCA_FQ_PIE_LIMIT] = {.type = NLA_U32},
[TCA_FQ_PIE_FLOWS] = {.type = NLA_U32},
[TCA_FQ_PIE_TARGET] = {.type = NLA_U32},
[TCA_FQ_PIE_TUPDATE] = {.type = NLA_U32},
[TCA_FQ_PIE_ALPHA] = {.type = NLA_U32},
[TCA_FQ_PIE_BETA] = {.type = NLA_U32},
[TCA_FQ_PIE_QUANTUM] = {.type = NLA_U32},
[TCA_FQ_PIE_MEMORY_LIMIT] = {.type = NLA_U32},
[TCA_FQ_PIE_ECN_PROB] = {.type = NLA_U32},
[TCA_FQ_PIE_ECN] = {.type = NLA_U32},
[TCA_FQ_PIE_BYTEMODE] = {.type = NLA_U32},
[TCA_FQ_PIE_DQ_RATE_ESTIMATOR] = {.type = NLA_U32},
};
static inline struct sk_buff *dequeue_head(struct fq_pie_flow *flow)
{
struct sk_buff *skb = flow->head;
flow->head = skb->next;
skb->next = NULL;
return skb;
}
static struct sk_buff *fq_pie_qdisc_dequeue(struct Qdisc *sch)
{
struct fq_pie_sched_data *q = qdisc_priv(sch);
struct sk_buff *skb = NULL;
struct fq_pie_flow *flow;
struct list_head *head;
u32 pkt_len;
begin:
head = &q->new_flows;
if (list_empty(head)) {
head = &q->old_flows;
if (list_empty(head))
return NULL;
}
flow = list_first_entry(head, struct fq_pie_flow, flowchain);
/* Flow has exhausted all its credits */
if (flow->deficit <= 0) {
flow->deficit += q->quantum;
list_move_tail(&flow->flowchain, &q->old_flows);
goto begin;
}
if (flow->head) {
skb = dequeue_head(flow);
pkt_len = qdisc_pkt_len(skb);
sch->qstats.backlog -= pkt_len;
sch->q.qlen--;
qdisc_bstats_update(sch, skb);
}
if (!skb) {
/* force a pass through old_flows to prevent starvation */
if (head == &q->new_flows && !list_empty(&q->old_flows))
list_move_tail(&flow->flowchain, &q->old_flows);
else
list_del_init(&flow->flowchain);
goto begin;
}
flow->qlen--;
flow->deficit -= pkt_len;
flow->backlog -= pkt_len;
q->memory_usage -= get_pie_cb(skb)->mem_usage;
pie_process_dequeue(skb, &q->p_params, &flow->vars, flow->backlog);
return skb;
}
static int fq_pie_change(struct Qdisc *sch, struct nlattr *opt,
struct netlink_ext_ack *extack)
{
struct fq_pie_sched_data *q = qdisc_priv(sch);
struct nlattr *tb[TCA_FQ_PIE_MAX + 1];
unsigned int len_dropped = 0;
unsigned int num_dropped = 0;
int err;
if (!opt)
return -EINVAL;
err = nla_parse_nested(tb, TCA_FQ_PIE_MAX, opt, fq_pie_policy, extack);
if (err < 0)
return err;
sch_tree_lock(sch);
if (tb[TCA_FQ_PIE_LIMIT]) {
u32 limit = nla_get_u32(tb[TCA_FQ_PIE_LIMIT]);
q->p_params.limit = limit;
sch->limit = limit;
}
if (tb[TCA_FQ_PIE_FLOWS]) {
if (q->flows) {
NL_SET_ERR_MSG_MOD(extack,
"Number of flows cannot be changed");
goto flow_error;
}
q->flows_cnt = nla_get_u32(tb[TCA_FQ_PIE_FLOWS]);
if (!q->flows_cnt || q->flows_cnt >= 65536) {
NL_SET_ERR_MSG_MOD(extack,
"Number of flows must range in [1..65535]");
goto flow_error;
}
}
/* convert from microseconds to pschedtime */
if (tb[TCA_FQ_PIE_TARGET]) {
/* target is in us */
u32 target = nla_get_u32(tb[TCA_FQ_PIE_TARGET]);
/* convert to pschedtime */
q->p_params.target =
PSCHED_NS2TICKS((u64)target * NSEC_PER_USEC);
}
/* tupdate is in jiffies */
if (tb[TCA_FQ_PIE_TUPDATE])
q->p_params.tupdate =
usecs_to_jiffies(nla_get_u32(tb[TCA_FQ_PIE_TUPDATE]));
if (tb[TCA_FQ_PIE_ALPHA])
q->p_params.alpha = nla_get_u32(tb[TCA_FQ_PIE_ALPHA]);
if (tb[TCA_FQ_PIE_BETA])
q->p_params.beta = nla_get_u32(tb[TCA_FQ_PIE_BETA]);
if (tb[TCA_FQ_PIE_QUANTUM])
q->quantum = nla_get_u32(tb[TCA_FQ_PIE_QUANTUM]);
if (tb[TCA_FQ_PIE_MEMORY_LIMIT])
q->memory_limit = nla_get_u32(tb[TCA_FQ_PIE_MEMORY_LIMIT]);
if (tb[TCA_FQ_PIE_ECN_PROB])
q->ecn_prob = nla_get_u32(tb[TCA_FQ_PIE_ECN_PROB]);
if (tb[TCA_FQ_PIE_ECN])
q->p_params.ecn = nla_get_u32(tb[TCA_FQ_PIE_ECN]);
if (tb[TCA_FQ_PIE_BYTEMODE])
q->p_params.bytemode = nla_get_u32(tb[TCA_FQ_PIE_BYTEMODE]);
if (tb[TCA_FQ_PIE_DQ_RATE_ESTIMATOR])
q->p_params.dq_rate_estimator =
nla_get_u32(tb[TCA_FQ_PIE_DQ_RATE_ESTIMATOR]);
/* Drop excess packets if new limit is lower */
while (sch->q.qlen > sch->limit) {
struct sk_buff *skb = fq_pie_qdisc_dequeue(sch);
len_dropped += qdisc_pkt_len(skb);
num_dropped += 1;
rtnl_kfree_skbs(skb, skb);
}
qdisc_tree_reduce_backlog(sch, num_dropped, len_dropped);
sch_tree_unlock(sch);
return 0;
flow_error:
sch_tree_unlock(sch);
return -EINVAL;
}
static void fq_pie_timer(struct timer_list *t)
{
struct fq_pie_sched_data *q = from_timer(q, t, adapt_timer);
struct Qdisc *sch = q->sch;
spinlock_t *root_lock; /* to lock qdisc for probability calculations */
u16 idx;
root_lock = qdisc_lock(qdisc_root_sleeping(sch));
spin_lock(root_lock);
for (idx = 0; idx < q->flows_cnt; idx++)
pie_calculate_probability(&q->p_params, &q->flows[idx].vars,
q->flows[idx].backlog);
/* reset the timer to fire after 'tupdate' jiffies. */
if (q->p_params.tupdate)
mod_timer(&q->adapt_timer, jiffies + q->p_params.tupdate);
spin_unlock(root_lock);
}
static int fq_pie_init(struct Qdisc *sch, struct nlattr *opt,
struct netlink_ext_ack *extack)
{
struct fq_pie_sched_data *q = qdisc_priv(sch);
int err;
u16 idx;
pie_params_init(&q->p_params);
sch->limit = 10 * 1024;
q->p_params.limit = sch->limit;
q->quantum = psched_mtu(qdisc_dev(sch));
q->sch = sch;
q->ecn_prob = 10;
q->flows_cnt = 1024;
q->memory_limit = SZ_32M;
INIT_LIST_HEAD(&q->new_flows);
INIT_LIST_HEAD(&q->old_flows);
if (opt) {
err = fq_pie_change(sch, opt, extack);
if (err)
return err;
}
err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
if (err)
goto init_failure;
q->flows = kvcalloc(q->flows_cnt, sizeof(struct fq_pie_flow),
GFP_KERNEL);
if (!q->flows) {
err = -ENOMEM;
goto init_failure;
}
for (idx = 0; idx < q->flows_cnt; idx++) {
struct fq_pie_flow *flow = q->flows + idx;
INIT_LIST_HEAD(&flow->flowchain);
pie_vars_init(&flow->vars);
}
timer_setup(&q->adapt_timer, fq_pie_timer, 0);
mod_timer(&q->adapt_timer, jiffies + HZ / 2);
return 0;
init_failure:
q->flows_cnt = 0;
return err;
}
static int fq_pie_dump(struct Qdisc *sch, struct sk_buff *skb)
{
struct fq_pie_sched_data *q = qdisc_priv(sch);
struct nlattr *opts;
opts = nla_nest_start(skb, TCA_OPTIONS);
if (!opts)
return -EMSGSIZE;
/* convert target from pschedtime to us */
if (nla_put_u32(skb, TCA_FQ_PIE_LIMIT, sch->limit) ||
nla_put_u32(skb, TCA_FQ_PIE_FLOWS, q->flows_cnt) ||
nla_put_u32(skb, TCA_FQ_PIE_TARGET,
((u32)PSCHED_TICKS2NS(q->p_params.target)) /
NSEC_PER_USEC) ||
nla_put_u32(skb, TCA_FQ_PIE_TUPDATE,
jiffies_to_usecs(q->p_params.tupdate)) ||
nla_put_u32(skb, TCA_FQ_PIE_ALPHA, q->p_params.alpha) ||
nla_put_u32(skb, TCA_FQ_PIE_BETA, q->p_params.beta) ||
nla_put_u32(skb, TCA_FQ_PIE_QUANTUM, q->quantum) ||
nla_put_u32(skb, TCA_FQ_PIE_MEMORY_LIMIT, q->memory_limit) ||
nla_put_u32(skb, TCA_FQ_PIE_ECN_PROB, q->ecn_prob) ||
nla_put_u32(skb, TCA_FQ_PIE_ECN, q->p_params.ecn) ||
nla_put_u32(skb, TCA_FQ_PIE_BYTEMODE, q->p_params.bytemode) ||
nla_put_u32(skb, TCA_FQ_PIE_DQ_RATE_ESTIMATOR,
q->p_params.dq_rate_estimator))
goto nla_put_failure;
return nla_nest_end(skb, opts);
nla_put_failure:
nla_nest_cancel(skb, opts);
return -EMSGSIZE;
}
static int fq_pie_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
{
struct fq_pie_sched_data *q = qdisc_priv(sch);
struct tc_fq_pie_xstats st = {
.packets_in = q->stats.packets_in,
.overlimit = q->stats.overlimit,
.overmemory = q->overmemory,
.dropped = q->stats.dropped,
.ecn_mark = q->stats.ecn_mark,
.new_flow_count = q->new_flow_count,
.memory_usage = q->memory_usage,
};
struct list_head *pos;
sch_tree_lock(sch);
list_for_each(pos, &q->new_flows)
st.new_flows_len++;
list_for_each(pos, &q->old_flows)
st.old_flows_len++;
sch_tree_unlock(sch);
return gnet_stats_copy_app(d, &st, sizeof(st));
}
static void fq_pie_reset(struct Qdisc *sch)
{
struct fq_pie_sched_data *q = qdisc_priv(sch);
u16 idx;
INIT_LIST_HEAD(&q->new_flows);
INIT_LIST_HEAD(&q->old_flows);
for (idx = 0; idx < q->flows_cnt; idx++) {
struct fq_pie_flow *flow = q->flows + idx;
/* Removes all packets from flow */
rtnl_kfree_skbs(flow->head, flow->tail);
flow->head = NULL;
INIT_LIST_HEAD(&flow->flowchain);
pie_vars_init(&flow->vars);
}
sch->q.qlen = 0;
sch->qstats.backlog = 0;
}
static void fq_pie_destroy(struct Qdisc *sch)
{
struct fq_pie_sched_data *q = qdisc_priv(sch);
tcf_block_put(q->block);
del_timer_sync(&q->adapt_timer);
kvfree(q->flows);
}
static struct Qdisc_ops fq_pie_qdisc_ops __read_mostly = {
.id = "fq_pie",
.priv_size = sizeof(struct fq_pie_sched_data),
.enqueue = fq_pie_qdisc_enqueue,
.dequeue = fq_pie_qdisc_dequeue,
.peek = qdisc_peek_dequeued,
.init = fq_pie_init,
.destroy = fq_pie_destroy,
.reset = fq_pie_reset,
.change = fq_pie_change,
.dump = fq_pie_dump,
.dump_stats = fq_pie_dump_stats,
.owner = THIS_MODULE,
};
static int __init fq_pie_module_init(void)
{
return register_qdisc(&fq_pie_qdisc_ops);
}
static void __exit fq_pie_module_exit(void)
{
unregister_qdisc(&fq_pie_qdisc_ops);
}
module_init(fq_pie_module_init);
module_exit(fq_pie_module_exit);
MODULE_DESCRIPTION("Flow Queue Proportional Integral controller Enhanced (FQ-PIE)");
MODULE_AUTHOR("Mohit P. Tahiliani");
MODULE_LICENSE("GPL");