From 8e165e20348b53583f6c6cb45865b89209f4aa13 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Tue, 25 Feb 2014 14:34:32 +0100 Subject: [PATCH] net: tcp: add mib counters to track zero window transitions Three counters are added: - one to track when we went from non-zero to zero window - one to track the reverse - one counter incremented when we want to announce zero window, but can't because we would shrink current window. Suggested-by: Eric Dumazet Signed-off-by: Florian Westphal Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- include/uapi/linux/snmp.h | 3 +++ net/ipv4/proc.c | 3 +++ net/ipv4/tcp_output.c | 12 +++++++++++- 3 files changed, 17 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h index bbaba22f2d1b..8d64a7e5d371 100644 --- a/include/uapi/linux/snmp.h +++ b/include/uapi/linux/snmp.h @@ -259,6 +259,9 @@ enum LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES, /* TCPSpuriousRtxHostQueues */ LINUX_MIB_BUSYPOLLRXPACKETS, /* BusyPollRxPackets */ LINUX_MIB_TCPAUTOCORKING, /* TCPAutoCorking */ + LINUX_MIB_TCPFROMZEROWINDOWADV, /* TCPFromZeroWindowAdv */ + LINUX_MIB_TCPTOZEROWINDOWADV, /* TCPToZeroWindowAdv */ + LINUX_MIB_TCPWANTZEROWINDOWADV, /* TCPWantZeroWindowAdv */ __LINUX_MIB_MAX }; diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c index a6c8a80ec9d6..99d2e9b6fac9 100644 --- a/net/ipv4/proc.c +++ b/net/ipv4/proc.c @@ -280,6 +280,9 @@ static const struct snmp_mib snmp4_net_list[] = { SNMP_MIB_ITEM("TCPSpuriousRtxHostQueues", LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES), SNMP_MIB_ITEM("BusyPollRxPackets", LINUX_MIB_BUSYPOLLRXPACKETS), SNMP_MIB_ITEM("TCPAutoCorking", LINUX_MIB_TCPAUTOCORKING), + SNMP_MIB_ITEM("TCPFromZeroWindowAdv", LINUX_MIB_TCPFROMZEROWINDOWADV), + SNMP_MIB_ITEM("TCPToZeroWindowAdv", LINUX_MIB_TCPTOZEROWINDOWADV), + SNMP_MIB_ITEM("TCPWantZeroWindowAdv", LINUX_MIB_TCPWANTZEROWINDOWADV), SNMP_MIB_SENTINEL }; diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 21e8a9f33287..c5eadec001c1 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -269,6 +269,7 @@ EXPORT_SYMBOL(tcp_select_initial_window); static u16 tcp_select_window(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); + u32 old_win = tp->rcv_wnd; u32 cur_win = tcp_receive_window(tp); u32 new_win = __tcp_select_window(sk); @@ -281,6 +282,9 @@ static u16 tcp_select_window(struct sock *sk) * * Relax Will Robinson. */ + if (new_win == 0) + NET_INC_STATS(sock_net(sk), + LINUX_MIB_TCPWANTZEROWINDOWADV); new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); } tp->rcv_wnd = new_win; @@ -298,8 +302,14 @@ static u16 tcp_select_window(struct sock *sk) new_win >>= tp->rx_opt.rcv_wscale; /* If we advertise zero window, disable fast path. */ - if (new_win == 0) + if (new_win == 0) { tp->pred_flags = 0; + if (old_win) + NET_INC_STATS(sock_net(sk), + LINUX_MIB_TCPTOZEROWINDOWADV); + } else if (old_win == 0) { + NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFROMZEROWINDOWADV); + } return new_win; } -- 2.30.2