Re: [PATCH] [TCP]: Fixes IW > 2 cases when TCP is application limited

[Stephen Hemminger <shemminger@osdl.org>]

On Fri, 04 Aug 2006 00:32:36 +0300
Ilpo  Järvinen <ilpo.jarvinen@helsinki.fi> wrote:

> Whenever a transfer is application limited, we are allowed at least
> initial window worth of data per window unless cwnd is previously
> less than that.
> 
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
> ---
>  net/ipv4/tcp_input.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index 738dad9..104af5d 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
> @@ -3541,7 +3541,8 @@ void tcp_cwnd_application_limited(struct
>  	if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open &&
>  	    sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
>  		/* Limited by application or receiver window. */
> -		u32 win_used = max(tp->snd_cwnd_used, 2U);
> +		u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk));
> +		u32 win_used = max(tp->snd_cwnd_used, init_win);
>  		if (win_used < tp->snd_cwnd) {
>  			tp->snd_ssthresh = tcp_current_ssthresh(sk);
>  			tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1;

This looks correct.

Some code reorganization would help. This function is only called on the
output side and could be moved over to tcp_output.c and made static.
This would allow for a greater possibility of compiler inlining (if it wants).