From patchwork Sun Feb 20 07:52:41 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Shan Wei X-Patchwork-Id: 83722 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 25AB6B7180 for ; Sun, 20 Feb 2011 18:55:47 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751900Ab1BTHze (ORCPT ); Sun, 20 Feb 2011 02:55:34 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:54574 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751702Ab1BTHze convert rfc822-to-8bit (ORCPT ); Sun, 20 Feb 2011 02:55:34 -0500 Received: from tang.cn.fujitsu.com (tang.cn.fujitsu.com [10.167.250.3]) by song.cn.fujitsu.com (Postfix) with ESMTP id B79AD170116; Sun, 20 Feb 2011 15:54:52 +0800 (CST) Received: from mailserver.fnst.cn.fujitus.com (tang.cn.fujitsu.com [127.0.0.1]) by tang.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id p1K7nAfT003826; Sun, 20 Feb 2011 15:49:10 +0800 Received: from [10.167.225.31] ([10.167.225.31]) by mailserver.fnst.cn.fujitus.com (Lotus Domino Release 8.5.1FP4) with ESMTP id 2011022015535288-176440 ; Sun, 20 Feb 2011 15:53:52 +0800 Message-ID: <4D60C849.40905@cn.fujitsu.com> Date: Sun, 20 Feb 2011 15:52:41 +0800 From: Shan Wei User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.13pre) Gecko/20101113 Shredder/3.1.7pre MIME-Version: 1.0 To: =?UTF-8?B?SWxwbyBKw6RydmluZW4=?= , David Miller , Network-Maillist , jheffner@psc.edu Subject: [PATCH]tcp: document tcp_max_ssthresh (Limited Slow-Start) X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-02-20 15:53:52, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-02-20 15:53:53 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Ilpo Järvinen Base on Ilpo's patch about documenting tcp_max_ssthresh. (see http://marc.info/?l=linux-netdev&m=117950581307310&w=2) According to errata of RFC3742, fix the number of segments increased during RTT time. Just to state the occasion to use this parameter, But about how to set parameter value, maybe some others can do it. Signed-off-by: Ilpo Järvinen Signed-off-by: Shan Wei --- Documentation/networking/ip-sysctl.txt | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-) diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index ac3b4a7..ea78aac 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -280,6 +280,17 @@ tcp_max_orphans - INTEGER more aggressively. Let me to remind again: each orphan eats up to ~64K of unswappable memory. +tcp_max_ssthresh - INTEGER + Limited Slow-Start for TCP with large congestion windows (cwnd) defined in + RFC3742. Limited slow-start is a mechanism to limit growth of the cwnd + on the region where cwnd is larger than tcp_max_ssthresh. TCP increases cwnd + by at most tcp_max_ssthresh segments, and by at least tcp_max_ssthresh/2 + segments per RTT when the cwnd is above tcp_max_ssthresh. + If TCP connection increased cwnd to thousands (or tens of thousands) segments, + and thousands of packets were being dropped during slow-start, you can set + tcp_max_ssthresh to improve performance for new TCP connection. + Default: 0 (off) + tcp_max_syn_backlog - INTEGER Maximal number of remembered connection requests, which are still did not receive an acknowledgment from connecting client.