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Message-Id: <1292642451-892-1-git-send-email-nanditad@google.com> Date: Fri, 17 Dec 2010 19:20:51 -0800 From: Nandita Dukkipati <nanditad@...gle.com> To: "David S. Miller" <davem@...emloft.net> Cc: netdev@...r.kernel.org, Tom Herbert <therbert@...gle.com>, Laurent Chavey <chavey@...gle.com>, Yuchung Cheng <ycheng@...gle.com>, Nandita Dukkipati <nanditad@...gle.com> Subject: [PATCH 1/1] TCP: increase default initial receive window. This patch changes the default initial receive window to 10 mss (defined constant). The default window is limited to the maximum of 10*1460 and 2*mss (when mss > 1460). Signed-off-by: Nandita Dukkipati <nanditad@...gle.com> --- include/net/tcp.h | 3 +++ net/ipv4/tcp_output.c | 11 ++++++++--- 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 2ab6c9c..6c25ba8 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -60,6 +60,9 @@ extern void tcp_time_wait(struct sock *sk, int state, int timeo); */ #define MAX_TCP_WINDOW 32767U +/* Offer an initial receive window of 10 mss. */ +#define TCP_DEFAULT_INIT_RCVWND 10 + /* Minimal accepted MSS. It is (60+60+8) - (20+20). */ #define TCP_MIN_MSS 88U diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 2d39066..dc7c096 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -228,10 +228,15 @@ void tcp_select_initial_window(int __space, __u32 mss, } } - /* Set initial window to value enough for senders, following RFC5681. */ + /* Set initial window to a value enough for senders starting with + * initial congestion window of TCP_DEFAULT_INIT_RCVWND. Place + * a limit on the initial window when mss is larger than 1460. + */ if (mss > (1 << *rcv_wscale)) { - int init_cwnd = rfc3390_bytes_to_packets(mss); - + int init_cwnd = TCP_DEFAULT_INIT_RCVWND; + if (mss > 1460) + init_cwnd = + max_t(u32, (1460 * TCP_DEFAULT_INIT_RCVWND) / mss, 2); /* when initializing use the value from init_rcv_wnd * rather than the default from above */ -- 1.7.3.1 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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