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Commit cadefe5f authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp_bbr: fix bbr pacing rate for internal pacing 



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: default avatarKevin Yang <yyd@google.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3f484a6e

include/net/tcp.h

+11 −0
Original line number Original line Diff line number Diff line
@@ -1184,6 +1184,17 @@ static inline bool tcp_is_cwnd_limited(const struct sock *sk) 
	return tp->is_cwnd_limited;

	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,

/* Something is really bad, we could not queue an additional packet,

 * because qdisc is full or receiver sent a 0 window.

 * because qdisc is full or receiver sent a 0 window.

 * We do not want to add fuel to the fire, or abort too early,

 * We do not want to add fuel to the fire, or abort too early,

net/ipv4/tcp_bbr.c

+5 −1
Original line number Original line Diff line number Diff line
@@ -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)

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 *= gain;

	rate >>= BBR_SCALE;

	rate >>= BBR_SCALE;

	rate *= USEC_PER_SEC;

	rate *= USEC_PER_SEC;

net/ipv4/tcp_output.c

+0 −14
Original line number Original line Diff line number Diff line
@@ -973,17 +973,6 @@ enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer) 
	return HRTIMER_NORESTART;

	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)

static void tcp_internal_pacing(struct sock *sk, const struct sk_buff *skb)

{

{

	u64 len_ns;

	u64 len_ns;
@@ -995,9 +984,6 @@ static void tcp_internal_pacing(struct sock *sk, const struct sk_buff *skb) 
	if (!rate || rate == ~0U)

	if (!rate || rate == ~0U)

		return;

		return;





	/* Should account for header sizes as sch_fq does,

	 * but lets make things simple.

	 */

	len_ns = (u64)skb->len * NSEC_PER_SEC;

	len_ns = (u64)skb->len * NSEC_PER_SEC;

	do_div(len_ns, rate);

	do_div(len_ns, rate);

	hrtimer_start(&tcp_sk(sk)->pacing_timer,

	hrtimer_start(&tcp_sk(sk)->pacing_timer,