Commit 756ee172 authored by Lawrence Brakmo's avatar Lawrence Brakmo Committed by David S. Miller
Browse files

tcp: replace cnt & rtt with struct in pkts_acked() 



Replace 2 arguments (cnt and rtt) in the congestion control modules'
pkts_acked() function with a struct. This will allow adding more
information without having to modify existing congestion control
modules (tcp_nv in particular needs bytes in flight when packet
was sent).

As proposed by Neal Cardwell in his comments to the tcp_nv patch.

Signed-off-by: default avatarLawrence Brakmo <brakmo@fb.com>
Acked-by: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent cf88585b

include/net/tcp.h

+6 −1
Original line number Diff line number Diff line
@@ -854,6 +854,11 @@ enum tcp_ca_ack_event_flags { 


union tcp_cc_info;



struct ack_sample {

	u32 pkts_acked;

	s32 rtt_us;

};



struct tcp_congestion_ops {

	struct list_head	list;

	u32 key;
@@ -877,7 +882,7 @@ struct tcp_congestion_ops { 
	/* new value of cwnd after loss (optional) */

	u32  (*undo_cwnd)(struct sock *sk);

	/* hook for packet ack accounting (optional) */

	void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);

	void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);

	/* get info for inet_diag (optional) */

	size_t (*get_info)(struct sock *sk, u32 ext, int *attr,

			   union tcp_cc_info *info);

net/ipv4/tcp_bic.c

+3 −3
Original line number Diff line number Diff line
@@ -197,15 +197,15 @@ static void bictcp_state(struct sock *sk, u8 new_state) 
/* Track delayed acknowledgment ratio using sliding window

 * ratio = (15*ratio + sample) / 16

 */

static void bictcp_acked(struct sock *sk, u32 cnt, s32 rtt)

static void bictcp_acked(struct sock *sk, const struct ack_sample *sample)

{

	const struct inet_connection_sock *icsk = inet_csk(sk);



	if (icsk->icsk_ca_state == TCP_CA_Open) {

		struct bictcp *ca = inet_csk_ca(sk);



		cnt -= ca->delayed_ack >> ACK_RATIO_SHIFT;

		ca->delayed_ack += cnt;

		ca->delayed_ack += sample->pkts_acked -

			(ca->delayed_ack >> ACK_RATIO_SHIFT);

	}

}

net/ipv4/tcp_cdg.c

+7 −7
Original line number Diff line number Diff line
@@ -294,12 +294,12 @@ static void tcp_cdg_cong_avoid(struct sock *sk, u32 ack, u32 acked) 
	ca->shadow_wnd = max(ca->shadow_wnd, ca->shadow_wnd + incr);

}



static void tcp_cdg_acked(struct sock *sk, u32 num_acked, s32 rtt_us)

static void tcp_cdg_acked(struct sock *sk, const struct ack_sample *sample)

{

	struct cdg *ca = inet_csk_ca(sk);

	struct tcp_sock *tp = tcp_sk(sk);



	if (rtt_us <= 0)

	if (sample->rtt_us <= 0)

		return;



	/* A heuristic for filtering delayed ACKs, adapted from:
@@ -307,20 +307,20 @@ static void tcp_cdg_acked(struct sock *sk, u32 num_acked, s32 rtt_us) 
	 * delay and rate based TCP mechanisms." TR 100219A. CAIA, 2010.

	 */

	if (tp->sacked_out == 0) {

		if (num_acked == 1 && ca->delack) {

		if (sample->pkts_acked == 1 && ca->delack) {

			/* A delayed ACK is only used for the minimum if it is

			 * provenly lower than an existing non-zero minimum.

			 */

			ca->rtt.min = min(ca->rtt.min, rtt_us);

			ca->rtt.min = min(ca->rtt.min, sample->rtt_us);

			ca->delack--;

			return;

		} else if (num_acked > 1 && ca->delack < 5) {

		} else if (sample->pkts_acked > 1 && ca->delack < 5) {

			ca->delack++;

		}

	}



	ca->rtt.min = min_not_zero(ca->rtt.min, rtt_us);

	ca->rtt.max = max(ca->rtt.max, rtt_us);

	ca->rtt.min = min_not_zero(ca->rtt.min, sample->rtt_us);

	ca->rtt.max = max(ca->rtt.max, sample->rtt_us);

}



static u32 tcp_cdg_ssthresh(struct sock *sk)

net/ipv4/tcp_cubic.c

+3 −3
Original line number Diff line number Diff line
@@ -437,21 +437,21 @@ static void hystart_update(struct sock *sk, u32 delay) 
/* Track delayed acknowledgment ratio using sliding window

 * ratio = (15*ratio + sample) / 16

 */

static void bictcp_acked(struct sock *sk, u32 cnt, s32 rtt_us)

static void bictcp_acked(struct sock *sk, const struct ack_sample *sample)

{

	const struct tcp_sock *tp = tcp_sk(sk);

	struct bictcp *ca = inet_csk_ca(sk);

	u32 delay;



	/* Some calls are for duplicates without timetamps */

	if (rtt_us < 0)

	if (sample->rtt_us < 0)

		return;



	/* Discard delay samples right after fast recovery */

	if (ca->epoch_start && (s32)(tcp_time_stamp - ca->epoch_start) < HZ)

		return;



	delay = (rtt_us << 3) / USEC_PER_MSEC;

	delay = (sample->rtt_us << 3) / USEC_PER_MSEC;

	if (delay == 0)

		delay = 1;

net/ipv4/tcp_htcp.c

+5 −5
Original line number Diff line number Diff line
@@ -99,7 +99,7 @@ static inline void measure_rtt(struct sock *sk, u32 srtt) 
}



static void measure_achieved_throughput(struct sock *sk,

					u32 pkts_acked, s32 rtt)

					const struct ack_sample *sample)

{

	const struct inet_connection_sock *icsk = inet_csk(sk);

	const struct tcp_sock *tp = tcp_sk(sk);
@@ -107,10 +107,10 @@ static void measure_achieved_throughput(struct sock *sk, 
	u32 now = tcp_time_stamp;



	if (icsk->icsk_ca_state == TCP_CA_Open)

		ca->pkts_acked = pkts_acked;

		ca->pkts_acked = sample->pkts_acked;



	if (rtt > 0)

		measure_rtt(sk, usecs_to_jiffies(rtt));

	if (sample->rtt_us > 0)

		measure_rtt(sk, usecs_to_jiffies(sample->rtt_us));



	if (!use_bandwidth_switch)

		return;
@@ -122,7 +122,7 @@ static void measure_achieved_throughput(struct sock *sk, 
		return;

	}



	ca->packetcount += pkts_acked;

	ca->packetcount += sample->pkts_acked;



	if (ca->packetcount >= tp->snd_cwnd - (ca->alpha >> 7 ? : 1) &&

	    now - ca->lasttime >= ca->minRTT &&

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