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Date: Mon, 24 Nov 2008 16:22:06 +0200
From: "Ilpo Järvinen" <ilpo.jarvinen@...sinki.fi>
To: David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org
Subject: [PATCH 09/10] tcp: more accurate fallback counters (DEBUGONLY)
Not for inclusion! For those who are interested enough on internals
while maintaining high-speed.
---
include/linux/snmp.h | 13 +++++++++++++
net/ipv4/proc.c | 13 +++++++++++++
net/ipv4/tcp_input.c | 47 ++++++++++++++++++++++++++++++++++++-----------
3 files changed, 62 insertions(+), 11 deletions(-)
diff --git a/include/linux/snmp.h b/include/linux/snmp.h
index aee3f1e..501186a 100644
--- a/include/linux/snmp.h
+++ b/include/linux/snmp.h
@@ -219,6 +219,19 @@ enum
LINUX_MIB_SACKSHIFTED,
LINUX_MIB_SACKMERGED,
LINUX_MIB_SACKSHIFTFALLBACK,
+ LINUX_MIB_SACKCOLLAPSEFALLBACKGSO,
+ LINUX_MIB_SACKCOLLAPSEFALLBACKSKBBITS,
+ LINUX_MIB_SACKCOLLAPSEFALLBACKSKBDATA,
+ LINUX_MIB_SACKCOLLAPSEFALLBACKBELOW,
+ LINUX_MIB_SACKCOLLAPSEFALLBACKFIRST,
+ LINUX_MIB_SACKCOLLAPSEFALLBACKPREVBITS,
+ LINUX_MIB_SACKCOLLAPSEFALLBACKMSS,
+ LINUX_MIB_SACKCOLLAPSEFALLBACKNOHEAD,
+ LINUX_MIB_SACKCOLLAPSEFALLBACKSHIFT,
+ LINUX_MIB_SACKCOLLAPSENOOPSEQ,
+ LINUX_MIB_SACKCOLLAPSENOOPSMALLPCOUNT,
+ LINUX_MIB_SACKCOLLAPSENOOPSMALLLEN,
+ LINUX_MIB_SACKCOLLAPSEHOLE,
__LINUX_MIB_MAX
};
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 731789b..1d37fcd 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -237,6 +237,19 @@ static const struct snmp_mib snmp4_net_list[] = {
SNMP_MIB_ITEM("TCPSackShifted", LINUX_MIB_SACKSHIFTED),
SNMP_MIB_ITEM("TCPSackMerged", LINUX_MIB_SACKMERGED),
SNMP_MIB_ITEM("TCPSackShiftFallback", LINUX_MIB_SACKSHIFTFALLBACK),
+ SNMP_MIB_ITEM("TCPSACKCOLLAPSEFALLBACKGSO", LINUX_MIB_SACKCOLLAPSEFALLBACKGSO),
+ SNMP_MIB_ITEM("TCPSACKCOLLAPSEFALLBACKSKBBITS", LINUX_MIB_SACKCOLLAPSEFALLBACKSKBBITS),
+ SNMP_MIB_ITEM("TCPSACKCOLLAPSEFALLBACKSKBDATA", LINUX_MIB_SACKCOLLAPSEFALLBACKSKBDATA),
+ SNMP_MIB_ITEM("TCPSACKCOLLAPSEFALLBACKBELOW", LINUX_MIB_SACKCOLLAPSEFALLBACKBELOW),
+ SNMP_MIB_ITEM("TCPSACKCOLLAPSEFALLBACKFIRST", LINUX_MIB_SACKCOLLAPSEFALLBACKFIRST),
+ SNMP_MIB_ITEM("TCPSACKCOLLAPSEFALLBACKPREVBITS", LINUX_MIB_SACKCOLLAPSEFALLBACKPREVBITS),
+ SNMP_MIB_ITEM("TCPSACKCOLLAPSEFALLBACKMSS", LINUX_MIB_SACKCOLLAPSEFALLBACKMSS),
+ SNMP_MIB_ITEM("TCPSACKCOLLAPSEFALLBACKNOHEAD", LINUX_MIB_SACKCOLLAPSEFALLBACKNOHEAD),
+ SNMP_MIB_ITEM("TCPSACKCOLLAPSEFALLBACKSHIFT", LINUX_MIB_SACKCOLLAPSEFALLBACKSHIFT),
+ SNMP_MIB_ITEM("TCPSACKCOLLAPSENOOPSEQ", LINUX_MIB_SACKCOLLAPSENOOPSEQ),
+ SNMP_MIB_ITEM("TCPSACKCOLLAPSENOOPSMALLPCOUNT", LINUX_MIB_SACKCOLLAPSENOOPSMALLPCOUNT),
+ SNMP_MIB_ITEM("TCPSACKCOLLAPSENOOPSMALLLEN", LINUX_MIB_SACKCOLLAPSENOOPSMALLLEN),
+ SNMP_MIB_ITEM("TCPSACKCOLLAPSEHOLE", LINUX_MIB_SACKCOLLAPSEHOLE),
SNMP_MIB_SENTINEL
};
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index d8235cf..ffa37f9 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1475,26 +1475,38 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
int len;
int in_sack;
- if (!sk_can_gso(sk))
+ if (!sk_can_gso(sk)) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKCOLLAPSEFALLBACKGSO);
goto fallback;
+ }
/* Normally R but no L won't result in plain S */
if (!dup_sack &&
- (TCP_SKB_CB(skb)->sacked & TCPCB_TAGBITS) == TCPCB_SACKED_RETRANS)
+ (TCP_SKB_CB(skb)->sacked & TCPCB_TAGBITS) == TCPCB_SACKED_RETRANS) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKCOLLAPSEFALLBACKSKBBITS);
goto fallback;
- if (!skb_can_shift(skb))
+ }
+ if (!skb_can_shift(skb)) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKCOLLAPSEFALLBACKSKBDATA);
goto fallback;
+ }
/* This frame is about to be dropped (was ACKed). */
- if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una))
+ if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKCOLLAPSEFALLBACKBELOW);
goto fallback;
+ }
/* Can only happen with delayed DSACK + discard craziness */
- if (unlikely(skb == tcp_write_queue_head(sk)))
+ if (unlikely(skb == tcp_write_queue_head(sk))) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKCOLLAPSEFALLBACKFIRST);
goto fallback;
+ }
prev = tcp_write_queue_prev(sk, skb);
- if ((TCP_SKB_CB(prev)->sacked & TCPCB_TAGBITS) != TCPCB_SACKED_ACKED)
+ if ((TCP_SKB_CB(prev)->sacked & TCPCB_TAGBITS) != TCPCB_SACKED_ACKED) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKCOLLAPSEFALLBACKPREVBITS);
goto fallback;
+ }
in_sack = !after(start_seq, TCP_SKB_CB(skb)->seq) &&
!before(end_seq, TCP_SKB_CB(skb)->end_seq);
@@ -1507,17 +1519,23 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
/* TODO: Fix DSACKs to not fragment already SACKed and we can
* drop this restriction as unnecessary
*/
- if (mss != tcp_shift_mss(prev))
+ if (mss != tcp_shift_mss(prev)) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKCOLLAPSEFALLBACKMSS);
goto fallback;
+ }
} else {
- if (!after(TCP_SKB_CB(skb)->end_seq, start_seq))
+ if (!after(TCP_SKB_CB(skb)->end_seq, start_seq)) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKCOLLAPSENOOPSEQ);
goto noop;
+ }
/* CHECKME: This is non-MSS split case only?, this will
* cause skipped skbs due to advancing loop btw, original
* has that feature too
*/
- if (tcp_skb_pcount(skb) <= 1)
+ if (tcp_skb_pcount(skb) <= 1) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKCOLLAPSENOOPSMALLPCOUNT);
goto noop;
+ }
in_sack = !after(start_seq, TCP_SKB_CB(skb)->seq);
if (!in_sack) {
@@ -1532,6 +1550,7 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
* it would make skb timestamp tracking considerably
* harder problem.
*/
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKCOLLAPSEFALLBACKNOHEAD);
goto fallback;
}
@@ -1548,12 +1567,15 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
/* TODO: Fix DSACKs to not fragment already SACKed and we can
* drop this restriction as unnecessary
*/
- if (mss != tcp_shift_mss(prev))
+ if (mss != tcp_shift_mss(prev)) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKCOLLAPSEFALLBACKMSS);
goto fallback;
+ }
if (len == mss) {
pcount = 1;
} else if (len < mss) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKCOLLAPSENOOPSMALLLEN);
goto noop;
} else {
pcount = len / mss;
@@ -1561,8 +1583,10 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
}
}
- if (!skb_shift(prev, skb, len))
+ if (!skb_shift(prev, skb, len)) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKCOLLAPSEFALLBACKSHIFT);
goto fallback;
+ }
if (!tcp_shifted_skb(sk, prev, skb, pcount, len, *fack_count, reord,
flag, mss))
goto out;
@@ -1583,6 +1607,7 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
len = skb->len;
if (skb_shift(prev, skb, len)) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKCOLLAPSEHOLE);
pcount += tcp_skb_pcount(skb);
tcp_shifted_skb(sk, prev, skb, tcp_skb_pcount(skb), len,
*fack_count, reord, flag, mss);
--
1.5.2.2
--
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