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net_sched: sch_fq: properly set sk->sk_pacing_status 

If fq_classify() recycles a struct fq_flow because
a socket structure has been reallocated, we do not
set sk->sk_pacing_status immediately, but later if the
flow becomes detached.

This means that any flow requiring pacing (BBR, or SO_MAX_PACING_RATE)
might fallback to TCP internal pacing, which requires a per-socket
high resolution timer, and therefore more cpu cycles.

Fixes: 218af599fa ("tcp: internal implementation for pacing")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2019-12-23 11:13:24 -08:00 committed by David S. Miller
parent 4e55a11aa3
commit bb3d0b8bf5
1 changed files with 8 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
net/sched/sch_fq.c
View File

@ -301,6 +301,9 @@ static struct fq_flow *fq_classify(struct sk_buff *skb, struct fq_sched_data *q)
f->socket_hash != sk->sk_hash)) {
f->credit = q->initial_quantum;
f->socket_hash = sk->sk_hash;
if (q->rate_enable)
smp_store_release(&sk->sk_pacing_status,
SK_PACING_FQ);
if (fq_flow_is_throttled(f))
fq_flow_unset_throttled(q, f);
f->time_next_packet = 0ULL;
@ -322,8 +325,12 @@ static struct fq_flow *fq_classify(struct sk_buff *skb, struct fq_sched_data *q)
fq_flow_set_detached(f);
f->sk = sk;
if (skb->sk == sk)
if (skb->sk == sk) {
f->socket_hash = sk->sk_hash;
if (q->rate_enable)
smp_store_release(&sk->sk_pacing_status,
SK_PACING_FQ);
}
f->credit = q->initial_quantum;
rb_link_node(&f->fq_node, parent, p);
@ -428,17 +435,9 @@ static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
f->qlen++;
qdisc_qstats_backlog_inc(sch, skb);
if (fq_flow_is_detached(f)) {
struct sock *sk = skb->sk;
fq_flow_add_tail(&q->new_flows, f);
if (time_after(jiffies, f->age + q->flow_refill_delay))
f->credit = max_t(u32, f->credit, q->quantum);
if (sk && q->rate_enable) {
if (unlikely(smp_load_acquire(&sk->sk_pacing_status) !=
SK_PACING_FQ))
smp_store_release(&sk->sk_pacing_status,
SK_PACING_FQ);
}
q->inactive_flows--;
}