Commit d5fb143d authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

tcp: move tcp_rack_advance() to tcp_input.c 



tcp_rack_advance() is called from tcp_ack() and tcp_sacktag_one().

Moving it to tcp_input.c allows the compiler to inline it and save
both space and cpu cycles in TCP fast path.

$ scripts/bloat-o-meter -t vmlinux.1 vmlinux.2
add/remove: 0/2 grow/shrink: 1/1 up/down: 98/-132 (-34)
Function                                     old     new   delta
tcp_ack                                     5741    5839     +98
tcp_sacktag_one                              407     395     -12
__pfx_tcp_rack_advance                        16       -     -16
tcp_rack_advance                             104       -    -104
Total: Before=22572680, After=22572646, 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/20260127032147.3498272-4-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 629a6886

include/net/tcp.h

+0 −2
Original line number Diff line number Diff line
@@ -2514,8 +2514,6 @@ void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced); 
extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb,

				u32 reo_wnd);

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);



/* tcp_plb.c */

net/ipv4/tcp_input.c

+32 −0
Original line number Diff line number Diff line
@@ -1558,6 +1558,38 @@ static int tcp_match_skb_to_sack(struct sock *sk, struct sk_buff *skb, 
	return in_sack;

}



/* Record the most recently (re)sent time among the (s)acked packets

 * This is "Step 3: Advance RACK.xmit_time and update RACK.RTT" from

 * draft-cheng-tcpm-rack-00.txt

 */

static void tcp_rack_advance(struct tcp_sock *tp, u8 sacked,

			     u32 end_seq, u64 xmit_time)

{

	u32 rtt_us;



	rtt_us = tcp_stamp_us_delta(tp->tcp_mstamp, xmit_time);

	if (rtt_us < tcp_min_rtt(tp) && (sacked & TCPCB_RETRANS)) {

		/* If the sacked packet was retransmitted, it's ambiguous

		 * whether the retransmission or the original (or the prior

		 * retransmission) was sacked.

		 *

		 * If the original is lost, there is no ambiguity. Otherwise

		 * we assume the original can be delayed up to aRTT + min_rtt.

		 * the aRTT term is bounded by the fast recovery or timeout,

		 * so it's at least one RTT (i.e., retransmission is at least

		 * an RTT later).

		 */

		return;

	}

	tp->rack.advanced = 1;

	tp->rack.rtt_us = rtt_us;

	if (tcp_skb_sent_after(xmit_time, tp->rack.mstamp,

			       end_seq, tp->rack.end_seq)) {

		tp->rack.mstamp = xmit_time;

		tp->rack.end_seq = end_seq;

	}

}



/* Mark the given newly-SACKed range as such, adjusting counters and hints. */

static u8 tcp_sacktag_one(struct sock *sk,

			  struct tcp_sacktag_state *state, u8 sacked,

net/ipv4/tcp_recovery.c

+0 −32
Original line number Diff line number Diff line
@@ -111,38 +111,6 @@ bool tcp_rack_mark_lost(struct sock *sk) 
	return !!timeout;

}



/* Record the most recently (re)sent time among the (s)acked packets

 * This is "Step 3: Advance RACK.xmit_time and update RACK.RTT" from

 * draft-cheng-tcpm-rack-00.txt

 */

void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,

		      u64 xmit_time)

{

	u32 rtt_us;



	rtt_us = tcp_stamp_us_delta(tp->tcp_mstamp, xmit_time);

	if (rtt_us < tcp_min_rtt(tp) && (sacked & TCPCB_RETRANS)) {

		/* If the sacked packet was retransmitted, it's ambiguous

		 * whether the retransmission or the original (or the prior

		 * retransmission) was sacked.

		 *

		 * If the original is lost, there is no ambiguity. Otherwise

		 * we assume the original can be delayed up to aRTT + min_rtt.

		 * the aRTT term is bounded by the fast recovery or timeout,

		 * so it's at least one RTT (i.e., retransmission is at least

		 * an RTT later).

		 */

		return;

	}

	tp->rack.advanced = 1;

	tp->rack.rtt_us = rtt_us;

	if (tcp_skb_sent_after(xmit_time, tp->rack.mstamp,

			       end_seq, tp->rack.end_seq)) {

		tp->rack.mstamp = xmit_time;

		tp->rack.end_seq = end_seq;

	}

}



/* We have waited long enough to accommodate reordering. Mark the expired

 * packets lost and retransmit them.

 */