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authorEric Dumazet <edumazet@google.com>2020-05-01 17:07:41 +0300
committerDavid S. Miller <davem@davemloft.net>2020-05-04 21:56:17 +0300
commit39d010504e6b4485d7ceee167743620dd33f4417 (patch)
tree96c551bbdb2fba46d2a0bd951edd8a0a079ea1ed /net
parentbf6dba76d278d296b385b436d3ac7de56c190d44 (diff)
downloadlinux-39d010504e6b4485d7ceee167743620dd33f4417.tar.xz
net_sched: sch_fq: add horizon attribute
QUIC servers would like to use SO_TXTIME, without having CAP_NET_ADMIN, to efficiently pace UDP packets. As far as sch_fq is concerned, we need to add safety checks, so that a buggy application does not fill the qdisc with packets having delivery time far in the future. This patch adds a configurable horizon (default: 10 seconds), and a configurable policy when a packet is beyond the horizon at enqueue() time: - either drop the packet (default policy) - or cap its delivery time to the horizon. $ tc -s -d qd sh dev eth0 qdisc fq 8022: root refcnt 257 limit 10000p flow_limit 100p buckets 1024 orphan_mask 1023 quantum 10Kb initial_quantum 51160b low_rate_threshold 550Kbit refill_delay 40.0ms timer_slack 10.000us horizon 10.000s Sent 1234215879 bytes 837099 pkt (dropped 21, overlimits 0 requeues 6) backlog 0b 0p requeues 6 flows 1191 (inactive 1177 throttled 0) gc 0 highprio 0 throttled 692 latency 11.480us pkts_too_long 0 alloc_errors 0 horizon_drops 21 horizon_caps 0 v2: fixed an overflow on 32bit kernels in fq_init(), reported by kbuild test robot <lkp@intel.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/sched/sch_fq.c59
1 files changed, 54 insertions, 5 deletions
diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index 4f0104243cc2..8f06a808c59a 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -100,6 +100,7 @@ struct fq_sched_data {
struct rb_root delayed; /* for rate limited flows */
u64 time_next_delayed_flow;
+ u64 ktime_cache; /* copy of last ktime_get_ns() */
unsigned long unthrottle_latency_ns;
struct fq_flow internal; /* for non classified or high prio packets */
@@ -109,12 +110,13 @@ struct fq_sched_data {
u32 flow_plimit; /* max packets per flow */
unsigned long flow_max_rate; /* optional max rate per flow */
u64 ce_threshold;
+ u64 horizon; /* horizon in ns */
u32 orphan_mask; /* mask for orphaned skb */
u32 low_rate_threshold;
struct rb_root *fq_root;
u8 rate_enable;
u8 fq_trees_log;
-
+ u8 horizon_drop;
u32 flows;
u32 inactive_flows;
u32 throttled_flows;
@@ -123,6 +125,8 @@ struct fq_sched_data {
u64 stat_internal_packets;
u64 stat_throttled;
u64 stat_ce_mark;
+ u64 stat_horizon_drops;
+ u64 stat_horizon_caps;
u64 stat_flows_plimit;
u64 stat_pkts_too_long;
u64 stat_allocation_errors;
@@ -402,8 +406,6 @@ static void flow_queue_add(struct fq_flow *flow, struct sk_buff *skb)
struct rb_node **p, *parent;
struct sk_buff *head, *aux;
- fq_skb_cb(skb)->time_to_send = skb->tstamp ?: ktime_get_ns();
-
head = flow->head;
if (!head ||
fq_skb_cb(skb)->time_to_send >= fq_skb_cb(flow->tail)->time_to_send) {
@@ -431,6 +433,12 @@ static void flow_queue_add(struct fq_flow *flow, struct sk_buff *skb)
rb_insert_color(&skb->rbnode, &flow->t_root);
}
+static bool fq_packet_beyond_horizon(const struct sk_buff *skb,
+ const struct fq_sched_data *q)
+{
+ return unlikely((s64)skb->tstamp > (s64)(q->ktime_cache + q->horizon));
+}
+
static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
@@ -440,6 +448,28 @@ static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
if (unlikely(sch->q.qlen >= sch->limit))
return qdisc_drop(skb, sch, to_free);
+ if (!skb->tstamp) {
+ fq_skb_cb(skb)->time_to_send = q->ktime_cache = ktime_get_ns();
+ } else {
+ /* Check if packet timestamp is too far in the future.
+ * Try first if our cached value, to avoid ktime_get_ns()
+ * cost in most cases.
+ */
+ if (fq_packet_beyond_horizon(skb, q)) {
+ /* Refresh our cache and check another time */
+ q->ktime_cache = ktime_get_ns();
+ if (fq_packet_beyond_horizon(skb, q)) {
+ if (q->horizon_drop) {
+ q->stat_horizon_drops++;
+ return qdisc_drop(skb, sch, to_free);
+ }
+ q->stat_horizon_caps++;
+ skb->tstamp = q->ktime_cache + q->horizon;
+ }
+ }
+ fq_skb_cb(skb)->time_to_send = skb->tstamp;
+ }
+
f = fq_classify(skb, q);
if (unlikely(f->qlen >= q->flow_plimit && f != &q->internal)) {
q->stat_flows_plimit++;
@@ -512,7 +542,7 @@ static struct sk_buff *fq_dequeue(struct Qdisc *sch)
goto out;
}
- now = ktime_get_ns();
+ q->ktime_cache = now = ktime_get_ns();
fq_check_throttled(q, now);
begin:
head = &q->new_flows;
@@ -765,6 +795,8 @@ static const struct nla_policy fq_policy[TCA_FQ_MAX + 1] = {
[TCA_FQ_LOW_RATE_THRESHOLD] = { .type = NLA_U32 },
[TCA_FQ_CE_THRESHOLD] = { .type = NLA_U32 },
[TCA_FQ_TIMER_SLACK] = { .type = NLA_U32 },
+ [TCA_FQ_HORIZON] = { .type = NLA_U32 },
+ [TCA_FQ_HORIZON_DROP] = { .type = NLA_U8 },
};
static int fq_change(struct Qdisc *sch, struct nlattr *opt,
@@ -854,7 +886,15 @@ static int fq_change(struct Qdisc *sch, struct nlattr *opt,
if (tb[TCA_FQ_TIMER_SLACK])
q->timer_slack = nla_get_u32(tb[TCA_FQ_TIMER_SLACK]);
+ if (tb[TCA_FQ_HORIZON])
+ q->horizon = (u64)NSEC_PER_USEC *
+ nla_get_u32(tb[TCA_FQ_HORIZON]);
+
+ if (tb[TCA_FQ_HORIZON_DROP])
+ q->horizon_drop = nla_get_u8(tb[TCA_FQ_HORIZON_DROP]);
+
if (!err) {
+
sch_tree_unlock(sch);
err = fq_resize(sch, fq_log);
sch_tree_lock(sch);
@@ -907,6 +947,9 @@ static int fq_init(struct Qdisc *sch, struct nlattr *opt,
q->timer_slack = 10 * NSEC_PER_USEC; /* 10 usec of hrtimer slack */
+ q->horizon = 10ULL * NSEC_PER_SEC; /* 10 seconds */
+ q->horizon_drop = 1; /* by default, drop packets beyond horizon */
+
/* Default ce_threshold of 4294 seconds */
q->ce_threshold = (u64)NSEC_PER_USEC * ~0U;
@@ -924,6 +967,7 @@ static int fq_dump(struct Qdisc *sch, struct sk_buff *skb)
{
struct fq_sched_data *q = qdisc_priv(sch);
u64 ce_threshold = q->ce_threshold;
+ u64 horizon = q->horizon;
struct nlattr *opts;
opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
@@ -933,6 +977,7 @@ static int fq_dump(struct Qdisc *sch, struct sk_buff *skb)
/* TCA_FQ_FLOW_DEFAULT_RATE is not used anymore */
do_div(ce_threshold, NSEC_PER_USEC);
+ do_div(horizon, NSEC_PER_USEC);
if (nla_put_u32(skb, TCA_FQ_PLIMIT, sch->limit) ||
nla_put_u32(skb, TCA_FQ_FLOW_PLIMIT, q->flow_plimit) ||
@@ -948,7 +993,9 @@ static int fq_dump(struct Qdisc *sch, struct sk_buff *skb)
q->low_rate_threshold) ||
nla_put_u32(skb, TCA_FQ_CE_THRESHOLD, (u32)ce_threshold) ||
nla_put_u32(skb, TCA_FQ_BUCKETS_LOG, q->fq_trees_log) ||
- nla_put_u32(skb, TCA_FQ_TIMER_SLACK, q->timer_slack))
+ nla_put_u32(skb, TCA_FQ_TIMER_SLACK, q->timer_slack) ||
+ nla_put_u32(skb, TCA_FQ_HORIZON, (u32)horizon) ||
+ nla_put_u8(skb, TCA_FQ_HORIZON_DROP, q->horizon_drop))
goto nla_put_failure;
return nla_nest_end(skb, opts);
@@ -979,6 +1026,8 @@ static int fq_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
st.unthrottle_latency_ns = min_t(unsigned long,
q->unthrottle_latency_ns, ~0U);
st.ce_mark = q->stat_ce_mark;
+ st.horizon_drops = q->stat_horizon_drops;
+ st.horizon_caps = q->stat_horizon_caps;
sch_tree_unlock(sch);
return gnet_stats_copy_app(d, &st, sizeof(st));