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net: tcp: split ack slow/fast events from cwnd_event

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The congestion control ops "cwnd_event" currently supports
CA_EVENT_FAST_ACK and CA_EVENT_SLOW_ACK events (among others).
Both FAST and SLOW_ACK are only used by Westwood congestion
control algorithm.

This removes both flags from cwnd_event and adds a new
in_ack_event callback for this. The goal is to be able to
provide more detailed information about ACKs, such as whether
ECE flag was set, or whether the ACK resulted in a window
update.

It is required for DataCenter TCP (DCTCP) congestion control
algorithm as it makes a different choice depending on ECE being
set or not.

Joint work with Daniel Borkmann and Glenn Judd.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Glenn Judd <glenn.judd@morganstanley.com>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Florian Westphal
2014-09-26 22:37:34 +02:00
committed by David S. Miller
parent 30e502a34b
commit 7354c8c389
3 changed files with 32 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
net/ipv4/tcp_input.c
View File

@@ -3362,6 +3362,14 @@ static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag)
}
}
static inline void tcp_in_ack_event(struct sock *sk, u32 flags)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
if (icsk->icsk_ca_ops->in_ack_event)
icsk->icsk_ca_ops->in_ack_event(sk, flags);
}
/* This routine deals with incoming acks, but not outgoing ones. */
static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
{
@@ -3421,7 +3429,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
tp->snd_una = ack;
flag |= FLAG_WIN_UPDATE;
tcp_ca_event(sk, CA_EVENT_FAST_ACK);
tcp_in_ack_event(sk, 0);
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPHPACKS);
} else {
@@ -3439,7 +3447,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
if (TCP_ECN_rcv_ecn_echo(tp, tcp_hdr(skb)))
flag |= FLAG_ECE;
tcp_ca_event(sk, CA_EVENT_SLOW_ACK);
tcp_in_ack_event(sk, CA_ACK_SLOWPATH);
}
/* We passed data and got it acked, remove any soft error