Commit 629a6886 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

tcp: move tcp_rack_update_reo_wnd() to tcp_input.c 



tcp_rack_update_reo_wnd() is called only once from tcp_ack()

Move it to tcp_input.c so that it can be inlined by the compiler
to save space and cpu cycles.

$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/2 grow/shrink: 1/0 up/down: 110/-153 (-43)
Function                                     old     new   delta
tcp_ack                                     5631    5741    +110
__pfx_tcp_rack_update_reo_wnd                 16       -     -16
tcp_rack_update_reo_wnd                      137       -    -137
Total: Before=22572723, After=22572680, chg -0.00%

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260127032147.3498272-3-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 773a7002

include/net/tcp.h

+0 −1
Original line number Diff line number Diff line
@@ -2517,7 +2517,6 @@ extern bool tcp_rack_mark_lost(struct sock *sk); 
extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,

			     u64 xmit_time);

extern void tcp_rack_reo_timeout(struct sock *sk);

extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs);



/* tcp_plb.c */

net/ipv4/tcp_input.c

+43 −0
Original line number Diff line number Diff line
@@ -4149,6 +4149,49 @@ static u32 tcp_newly_delivered(struct sock *sk, u32 prior_delivered, 
	return delivered;

}



/* Updates the RACK's reo_wnd based on DSACK and no. of recoveries.

 *

 * If a DSACK is received that seems like it may have been due to reordering

 * triggering fast recovery, increment reo_wnd by min_rtt/4 (upper bounded

 * by srtt), since there is possibility that spurious retransmission was

 * due to reordering delay longer than reo_wnd.

 *

 * Persist the current reo_wnd value for TCP_RACK_RECOVERY_THRESH (16)

 * no. of successful recoveries (accounts for full DSACK-based loss

 * recovery undo). After that, reset it to default (min_rtt/4).

 *

 * At max, reo_wnd is incremented only once per rtt. So that the new

 * DSACK on which we are reacting, is due to the spurious retx (approx)

 * after the reo_wnd has been updated last time.

 *

 * reo_wnd is tracked in terms of steps (of min_rtt/4), rather than

 * absolute value to account for change in rtt.

 */

static void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs)

{

	struct tcp_sock *tp = tcp_sk(sk);



	if ((READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_recovery) &

	     TCP_RACK_STATIC_REO_WND) ||

	    !rs->prior_delivered)

		return;



	/* Disregard DSACK if a rtt has not passed since we adjusted reo_wnd */

	if (before(rs->prior_delivered, tp->rack.last_delivered))

		tp->rack.dsack_seen = 0;



	/* Adjust the reo_wnd if update is pending */

	if (tp->rack.dsack_seen) {

		tp->rack.reo_wnd_steps = min_t(u32, 0xFF,

					       tp->rack.reo_wnd_steps + 1);

		tp->rack.dsack_seen = 0;

		tp->rack.last_delivered = tp->delivered;

		tp->rack.reo_wnd_persist = TCP_RACK_RECOVERY_THRESH;

	} else if (!tp->rack.reo_wnd_persist) {

		tp->rack.reo_wnd_steps = 1;

	}

}



/* This routine deals with incoming acks, but not outgoing ones. */

static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)

{

net/ipv4/tcp_recovery.c

+0 −43
Original line number Diff line number Diff line
@@ -166,49 +166,6 @@ void tcp_rack_reo_timeout(struct sock *sk) 
		tcp_rearm_rto(sk);

}



/* Updates the RACK's reo_wnd based on DSACK and no. of recoveries.

 *

 * If a DSACK is received that seems like it may have been due to reordering

 * triggering fast recovery, increment reo_wnd by min_rtt/4 (upper bounded

 * by srtt), since there is possibility that spurious retransmission was

 * due to reordering delay longer than reo_wnd.

 *

 * Persist the current reo_wnd value for TCP_RACK_RECOVERY_THRESH (16)

 * no. of successful recoveries (accounts for full DSACK-based loss

 * recovery undo). After that, reset it to default (min_rtt/4).

 *

 * At max, reo_wnd is incremented only once per rtt. So that the new

 * DSACK on which we are reacting, is due to the spurious retx (approx)

 * after the reo_wnd has been updated last time.

 *

 * reo_wnd is tracked in terms of steps (of min_rtt/4), rather than

 * absolute value to account for change in rtt.

 */

void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs)

{

	struct tcp_sock *tp = tcp_sk(sk);



	if ((READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_recovery) &

	     TCP_RACK_STATIC_REO_WND) ||

	    !rs->prior_delivered)

		return;



	/* Disregard DSACK if a rtt has not passed since we adjusted reo_wnd */

	if (before(rs->prior_delivered, tp->rack.last_delivered))

		tp->rack.dsack_seen = 0;



	/* Adjust the reo_wnd if update is pending */

	if (tp->rack.dsack_seen) {

		tp->rack.reo_wnd_steps = min_t(u32, 0xFF,

					       tp->rack.reo_wnd_steps + 1);

		tp->rack.dsack_seen = 0;

		tp->rack.last_delivered = tp->delivered;

		tp->rack.reo_wnd_persist = TCP_RACK_RECOVERY_THRESH;

	} else if (!tp->rack.reo_wnd_persist) {

		tp->rack.reo_wnd_steps = 1;

	}

}



/* RFC6582 NewReno recovery for non-SACK connection. It simply retransmits

 * the next unacked packet upon receiving

 * a) three or more DUPACKs to start the fast recovery