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Commit 30cfd0ba authored by Stephen Hemminger's avatar Stephen Hemminger Committed by David S. Miller
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[TCP]: congestion control API pass RTT in microseconds 



This patch changes the API for the callback that is done after an ACK is
received. It solves a couple of issues:

  * Some congestion controls want higher resolution value of RTT
    (controlled by TCP_CONG_RTT_SAMPLE flag). These don't really want a ktime, but
    all compute a RTT in microseconds.

  * Other congestion control could use RTT at jiffies resolution.

To keep API consistent the units should be the same for both cases, just the
resolution should change.

Signed-off-by: default avatarStephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6a302358

include/net/tcp.h

+1 −1
Original line number Diff line number Diff line
@@ -660,7 +660,7 @@ 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, ktime_t last);

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

	/* get info for inet_diag (optional) */

	void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);

net/ipv4/tcp_bic.c

+1 −1
Original line number Diff line number Diff line
@@ -206,7 +206,7 @@ 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, ktime_t last)

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

{

	const struct inet_connection_sock *icsk = inet_csk(sk);

net/ipv4/tcp_cubic.c

+1 −1
Original line number Diff line number Diff line
@@ -334,7 +334,7 @@ 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, ktime_t last)

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

{

	const struct inet_connection_sock *icsk = inet_csk(sk);

net/ipv4/tcp_htcp.c

+1 −1
Original line number Diff line number Diff line
@@ -98,7 +98,7 @@ static inline void measure_rtt(struct sock *sk) 
	}

}



static void measure_achieved_throughput(struct sock *sk, u32 pkts_acked, ktime_t last)

static void measure_achieved_throughput(struct sock *sk, u32 pkts_acked, s32 rtt)

{

	const struct inet_connection_sock *icsk = inet_csk(sk);

	const struct tcp_sock *tp = tcp_sk(sk);

net/ipv4/tcp_illinois.c

+3 −5
Original line number Diff line number Diff line
@@ -83,18 +83,16 @@ static void tcp_illinois_init(struct sock *sk) 
}



/* Measure RTT for each ack. */

static void tcp_illinois_acked(struct sock *sk, u32 pkts_acked, ktime_t last)

static void tcp_illinois_acked(struct sock *sk, u32 pkts_acked, s32 rtt)

{

	struct illinois *ca = inet_csk_ca(sk);

	u32 rtt;



	ca->acked = pkts_acked;



	if (ktime_equal(last, net_invalid_timestamp()))

	/* dup ack, no rtt sample */

	if (rtt < 0)

		return;



	rtt = ktime_to_us(net_timedelta(last));



	/* ignore bogus values, this prevents wraparound in alpha math */

	if (rtt > RTT_MAX)

		rtt = RTT_MAX;