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tcp_bbr: fix bbr pacing rate for internal pacing

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This commit makes BBR use only the MSS (without any headers) to
calculate pacing rates when internal TCP-layer pacing is used.

This is necessary to achieve the correct pacing behavior in this case,
since tcp_internal_pacing() uses only the payload length to calculate
pacing delays.

Signed-off-by: Kevin Yang <yyd@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2018-06-20 16:07:35 -04:00 committed by David S. Miller
parent 3f484a6e76
commit cadefe5f58
3 changed files with 16 additions and 15 deletions
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11
include/net/tcp.h
View File

@ -1184,6 +1184,17 @@ static inline bool tcp_is_cwnd_limited(const struct sock *sk)
return tp->is_cwnd_limited;
}
/* BBR congestion control needs pacing.
* Same remark for SO_MAX_PACING_RATE.
* sch_fq packet scheduler is efficiently handling pacing,
* but is not always installed/used.
* Return true if TCP stack should pace packets itself.
*/
static inline bool tcp_needs_internal_pacing(const struct sock *sk)
{
return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED;
}
/* Something is really bad, we could not queue an additional packet,
* because qdisc is full or receiver sent a 0 window.
* We do not want to add fuel to the fire, or abort too early,

6
net/ipv4/tcp_bbr.c
View File

@ -205,7 +205,11 @@ static u32 bbr_bw(const struct sock *sk)
*/
static u64 bbr_rate_bytes_per_sec(struct sock *sk, u64 rate, int gain)
{
rate *= tcp_mss_to_mtu(sk, tcp_sk(sk)->mss_cache);
unsigned int mss = tcp_sk(sk)->mss_cache;
if (!tcp_needs_internal_pacing(sk))
mss = tcp_mss_to_mtu(sk, mss);
rate *= mss;
rate *= gain;
rate >>= BBR_SCALE;
rate *= USEC_PER_SEC;

14
net/ipv4/tcp_output.c
View File

@ -973,17 +973,6 @@ enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer)
return HRTIMER_NORESTART;
}
/* BBR congestion control needs pacing.
* Same remark for SO_MAX_PACING_RATE.
* sch_fq packet scheduler is efficiently handling pacing,
* but is not always installed/used.
* Return true if TCP stack should pace packets itself.
*/
static bool tcp_needs_internal_pacing(const struct sock *sk)
{
return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED;
}
static void tcp_internal_pacing(struct sock *sk, const struct sk_buff *skb)
{
u64 len_ns;
@ -995,9 +984,6 @@ static void tcp_internal_pacing(struct sock *sk, const struct sk_buff *skb)
if (!rate || rate == ~0U)
return;
/* Should account for header sizes as sch_fq does,
* but lets make things simple.
*/
len_ns = (u64)skb->len * NSEC_PER_SEC;
do_div(len_ns, rate);
hrtimer_start(&tcp_sk(sk)->pacing_timer,