Commit 40b215e5 authored by Pavel Emelyanov's avatar Pavel Emelyanov Committed by David S. Miller
Browse files

tcp: de-bloat a bit with factoring NET_INC_STATS_BH out 



There are some places in TCP that select one MIB index to
bump snmp statistics like this:

	if (<something>)
		NET_INC_STATS_BH(<some_id>);
	else if (<something_else>)
		NET_INC_STATS_BH(<some_other_id>);
	...
	else
		NET_INC_STATS_BH(<default_id>);

or in a more tricky but still similar way.

On the other hand, this NET_INC_STATS_BH is a camouflaged
increment of percpu variable, which is not that small.

Factoring those cases out de-bloats 235 bytes on non-preemptible
i386 config and drives parts of the code into 80 columns.

add/remove: 0/0 grow/shrink: 0/7 up/down: 0/-235 (-235)
function                                     old     new   delta
tcp_fastretrans_alert                       1437    1424     -13
tcp_dsack_set                                137     124     -13
tcp_xmit_retransmit_queue                    690     676     -14
tcp_try_undo_recovery                        283     265     -18
tcp_sacktag_write_queue                     1550    1515     -35
tcp_update_reordering                        162     106     -56
tcp_retransmit_timer                         990     904     -86

Signed-off-by: default avatarPavel Emelyanov <xemul@openvz.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b4653e99

net/ipv4/tcp_input.c

+32 −14
Original line number Diff line number Diff line
@@ -947,17 +947,21 @@ static void tcp_update_reordering(struct sock *sk, const int metric, 
{

	struct tcp_sock *tp = tcp_sk(sk);

	if (metric > tp->reordering) {

		int mib_idx;



		tp->reordering = min(TCP_MAX_REORDERING, metric);



		/* This exciting event is worth to be remembered. 8) */

		if (ts)

			NET_INC_STATS_BH(LINUX_MIB_TCPTSREORDER);

			mib_idx = LINUX_MIB_TCPTSREORDER;

		else if (tcp_is_reno(tp))

			NET_INC_STATS_BH(LINUX_MIB_TCPRENOREORDER);

			mib_idx = LINUX_MIB_TCPRENOREORDER;

		else if (tcp_is_fack(tp))

			NET_INC_STATS_BH(LINUX_MIB_TCPFACKREORDER);

			mib_idx = LINUX_MIB_TCPFACKREORDER;

		else

			NET_INC_STATS_BH(LINUX_MIB_TCPSACKREORDER);

			mib_idx = LINUX_MIB_TCPSACKREORDER;



		NET_INC_STATS_BH(mib_idx);

#if FASTRETRANS_DEBUG > 1

		printk(KERN_DEBUG "Disorder%d %d %u f%u s%u rr%d\n",

		       tp->rx_opt.sack_ok, inet_csk(sk)->icsk_ca_state,
@@ -1456,18 +1460,22 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, 
		if (!tcp_is_sackblock_valid(tp, dup_sack,

					    sp[used_sacks].start_seq,

					    sp[used_sacks].end_seq)) {

			int mib_idx;



			if (dup_sack) {

				if (!tp->undo_marker)

					NET_INC_STATS_BH(LINUX_MIB_TCPDSACKIGNOREDNOUNDO);

					mib_idx = LINUX_MIB_TCPDSACKIGNOREDNOUNDO;

				else

					NET_INC_STATS_BH(LINUX_MIB_TCPDSACKIGNOREDOLD);

					mib_idx = LINUX_MIB_TCPDSACKIGNOREDOLD;

			} else {

				/* Don't count olds caused by ACK reordering */

				if ((TCP_SKB_CB(ack_skb)->ack_seq != tp->snd_una) &&

				    !after(sp[used_sacks].end_seq, tp->snd_una))

					continue;

				NET_INC_STATS_BH(LINUX_MIB_TCPSACKDISCARD);

				mib_idx = LINUX_MIB_TCPSACKDISCARD;

			}



			NET_INC_STATS_BH(mib_idx);

			if (i == 0)

				first_sack_index = -1;

			continue;
@@ -2380,15 +2388,19 @@ static int tcp_try_undo_recovery(struct sock *sk) 
	struct tcp_sock *tp = tcp_sk(sk);



	if (tcp_may_undo(tp)) {

		int mib_idx;



		/* Happy end! We did not retransmit anything

		 * or our original transmission succeeded.

		 */

		DBGUNDO(sk, inet_csk(sk)->icsk_ca_state == TCP_CA_Loss ? "loss" : "retrans");

		tcp_undo_cwr(sk, 1);

		if (inet_csk(sk)->icsk_ca_state == TCP_CA_Loss)

			NET_INC_STATS_BH(LINUX_MIB_TCPLOSSUNDO);

			mib_idx = LINUX_MIB_TCPLOSSUNDO;

		else

			NET_INC_STATS_BH(LINUX_MIB_TCPFULLUNDO);

			mib_idx = LINUX_MIB_TCPFULLUNDO;



		NET_INC_STATS_BH(mib_idx);

		tp->undo_marker = 0;

	}

	if (tp->snd_una == tp->high_seq && tcp_is_reno(tp)) {
@@ -2560,7 +2572,7 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked, int flag) 
	int is_dupack = !(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP));

	int do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) &&

				    (tcp_fackets_out(tp) > tp->reordering));

	int fast_rexmit = 0;

	int fast_rexmit = 0, mib_idx;



	if (WARN_ON(!tp->packets_out && tp->sacked_out))

		tp->sacked_out = 0;
@@ -2683,9 +2695,11 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked, int flag) 
		/* Otherwise enter Recovery state */



		if (tcp_is_reno(tp))

			NET_INC_STATS_BH(LINUX_MIB_TCPRENORECOVERY);

			mib_idx = LINUX_MIB_TCPRENORECOVERY;

		else

			NET_INC_STATS_BH(LINUX_MIB_TCPSACKRECOVERY);

			mib_idx = LINUX_MIB_TCPSACKRECOVERY;



		NET_INC_STATS_BH(mib_idx);



		tp->high_seq = tp->snd_nxt;

		tp->prior_ssthresh = 0;
@@ -3700,10 +3714,14 @@ static inline int tcp_sack_extend(struct tcp_sack_block *sp, u32 seq, 
static void tcp_dsack_set(struct tcp_sock *tp, u32 seq, u32 end_seq)

{

	if (tcp_is_sack(tp) && sysctl_tcp_dsack) {

		int mib_idx;



		if (before(seq, tp->rcv_nxt))

			NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOLDSENT);

			mib_idx = LINUX_MIB_TCPDSACKOLDSENT;

		else

			NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFOSENT);

			mib_idx = LINUX_MIB_TCPDSACKOFOSENT;



		NET_INC_STATS_BH(mib_idx);



		tp->rx_opt.dsack = 1;

		tp->duplicate_sack[0].start_seq = seq;

net/ipv4/tcp_output.c

+5 −2
Original line number Diff line number Diff line
@@ -1985,14 +1985,17 @@ void tcp_xmit_retransmit_queue(struct sock *sk) 


			if (sacked & TCPCB_LOST) {

				if (!(sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS))) {

					int mib_idx;



					if (tcp_retransmit_skb(sk, skb)) {

						tp->retransmit_skb_hint = NULL;

						return;

					}

					if (icsk->icsk_ca_state != TCP_CA_Loss)

						NET_INC_STATS_BH(LINUX_MIB_TCPFASTRETRANS);

						mib_idx = LINUX_MIB_TCPFASTRETRANS;

					else

						NET_INC_STATS_BH(LINUX_MIB_TCPSLOWSTARTRETRANS);

						mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS;

					NET_INC_STATS_BH(mib_idx);



					if (skb == tcp_write_queue_head(sk))

						inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,

net/ipv4/tcp_timer.c

+9 −6
Original line number Diff line number Diff line
@@ -326,24 +326,27 @@ static void tcp_retransmit_timer(struct sock *sk) 
		goto out;



	if (icsk->icsk_retransmits == 0) {

		int mib_idx;



		if (icsk->icsk_ca_state == TCP_CA_Disorder ||

		    icsk->icsk_ca_state == TCP_CA_Recovery) {

			if (tcp_is_sack(tp)) {

				if (icsk->icsk_ca_state == TCP_CA_Recovery)

					NET_INC_STATS_BH(LINUX_MIB_TCPSACKRECOVERYFAIL);

					mib_idx = LINUX_MIB_TCPSACKRECOVERYFAIL;

				else

					NET_INC_STATS_BH(LINUX_MIB_TCPSACKFAILURES);

					mib_idx = LINUX_MIB_TCPSACKFAILURES;

			} else {

				if (icsk->icsk_ca_state == TCP_CA_Recovery)

					NET_INC_STATS_BH(LINUX_MIB_TCPRENORECOVERYFAIL);

					mib_idx = LINUX_MIB_TCPRENORECOVERYFAIL;

				else

					NET_INC_STATS_BH(LINUX_MIB_TCPRENOFAILURES);

					mib_idx = LINUX_MIB_TCPRENOFAILURES;

			}

		} else if (icsk->icsk_ca_state == TCP_CA_Loss) {

			NET_INC_STATS_BH(LINUX_MIB_TCPLOSSFAILURES);

			mib_idx = LINUX_MIB_TCPLOSSFAILURES;

		} else {

			NET_INC_STATS_BH(LINUX_MIB_TCPTIMEOUTS);

			mib_idx = LINUX_MIB_TCPTIMEOUTS;

		}

		NET_INC_STATS_BH(mib_idx);

	}



	if (tcp_use_frto(sk)) {

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