kernel.git/include/net/tcp.h, branch linux-2.6.38.y

TCP: increase default initial receive window.

2010-12-21T05:33:00Z

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). draft-ietf-tcpm-initcwnd-00 is a proposal to the IETF that recommends increasing TCP's initial congestion window to 10 mss or about 15KB. Leading up to this proposal were several large-scale live Internet experiments with an initial congestion window of 10 mss (IW10), where we showed that the average latency of HTTP responses improved by approximately 10%. This was accompanied by a slight increase in retransmission rate (0.5%), most of which is coming from applications opening multiple simultaneous connections. To understand the extreme worst case scenarios, and fairness issues (IW10 versus IW3), we further conducted controlled testbed experiments. We came away finding minimal negative impact even under low link bandwidths (dial-ups) and small buffers. These results are extremely encouraging to adopting IW10. However, an initial congestion window of 10 mss is useless unless a TCP receiver advertises an initial receive window of at least 10 mss. Fortunately, in the large-scale Internet experiments we found that most widely used operating systems advertised large initial receive windows of 64KB, allowing us to experiment with a wide range of initial congestion windows. Linux systems were among the few exceptions that advertised a small receive window of 6KB. The purpose of this patch is to fix this shortcoming. References: 1. A comprehensive list of all IW10 references to date. http://code.google.com/speed/protocols/tcpm-IW10.html 2. Paper describing results from large-scale Internet experiments with IW10. http://ccr.sigcomm.org/drupal/?q=node/621 3. Controlled testbed experiments under worst case scenarios and a fairness study. http://www.ietf.org/proceedings/79/slides/tcpm-0.pdf 4. Raw test data from testbed experiments (Linux senders/receivers) with initial congestion and receive windows of both 10 mss. http://research.csc.ncsu.edu/netsrv/?q=content/iw10 5. Internet-Draft. Increasing TCP's Initial Window. https://datatracker.ietf.org/doc/draft-ietf-tcpm-initcwnd/ Signed-off-by: Nandita Dukkipati Acked-by: Eric Dumazet Signed-off-by: David S. Miller

net: kill unused macros

2010-12-20T05:59:35Z

These macros never be used, so remove them. Signed-off-by: Shan Wei Signed-off-by: David S. Miller

tcp: relax tcp_paws_check()

2010-12-16T22:08:34Z

Some windows versions have wrong RFC1323 implementations, with SYN and SYNACKS messages containing zero tcp timestamps. We relaxed in commit fc1ad92dfc4e363 the passive connection case (Windows connects to a linux machine), but the reverse case (linux connects to a Windows machine) has an analogue problem when tsvals from windows machine are 'negative' (high order bit set) : PAWS triggers and we drops incoming messages. Fix this by making zero ts_recent value special, allowing frame to be processed. Based on a report and initial patch from Dmitiy Balakin Bugzilla reference : https://bugzilla.kernel.org/show_bug.cgi?id=24842 Reported-by: dmitriy.balakin@nicneiron.ru Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

net: kill unused macros from head file

2010-12-02T21:27:33Z

These macros have been defined for several years since v2.6.12-rc2（tracing by git）, but never be used. So remove them. Signed-off-by: Shan Wei Signed-off-by: David S. Miller

timewait_sock: Create and use getpeer op.

2010-12-02T02:09:13Z

The only thing AF-specific about remembering the timestamp for a time-wait TCP socket is getting the peer. Abstract that behind a new timewait_sock_ops vector. Support for real IPV6 sockets is not filled in yet, but curiously this makes timewait recycling start to work for v4-mapped ipv6 sockets. Signed-off-by: David S. Miller

inet: Turn ->remember_stamp into ->get_peer in connection AF ops.

2010-11-30T20:28:06Z

Then we can make a completely generic tcp_remember_stamp() that uses ->get_peer() as a helper, minimizing the AF specific code and minimizing the eventual code duplication when we implement the ipv6 side of TW recycling. Signed-off-by: David S. Miller

net: avoid limits overflow

2010-11-10T20:12:00Z

Robin Holt tried to boot a 16TB machine and found some limits were reached : sysctl_tcp_mem[2], sysctl_udp_mem[2] We can switch infrastructure to use long "instead" of "int", now atomic_long_t primitives are available for free. Signed-off-by: Eric Dumazet Reported-by: Robin Holt Reviewed-by: Robin Holt Signed-off-by: Andrew Morton Signed-off-by: David S. Miller

tcp: tcp_enter_quickack_mode can be static

2010-09-30T02:45:36Z

Function only used in tcp_input.c Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller

Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6

2010-09-27T08:03:03Z

Conflicts: drivers/net/qlcnic/qlcnic_init.c net/ipv4/ip_output.c

tcp: Prevent overzealous packetization by SWS logic.

2010-09-15T19:01:44Z

If peer uses tiny MSS (say, 75 bytes) and similarly tiny advertised window, the SWS logic will packetize to half the MSS unnecessarily. This causes problems with some embedded devices. However for large MSS devices we do want to half-MSS packetize otherwise we never get enough packets into the pipe for things like fast retransmit and recovery to work. Be careful also to handle the case where MSS > window, otherwise we'll never send until the probe timer. Reported-by: ツ Leandro Melo de Sales Signed-off-by: David S. Miller