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tcp: de-bloat a bit with factoring NET_INC_STATS_BH out
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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: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Pavel Emelyanov authored and David S. Miller committed Jul 3, 2008
1 parent b4653e9 commit 40b215e
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Showing 3 changed files with 46 additions and 22 deletions.
46 changes: 32 additions & 14 deletions net/ipv4/tcp_input.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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)) {
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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;
Expand Down
7 changes: 5 additions & 2 deletions net/ipv4/tcp_output.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand Down
15 changes: 9 additions & 6 deletions net/ipv4/tcp_timer.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)) {
Expand Down

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