From mboxrd@z Thu Jan 1 00:00:00 1970 From: tsuna Subject: Re: [PATCH] tcp: Implement a two-level initial RTO as per draft RFC 2988bis-02. Date: Wed, 18 May 2011 23:42:30 -0700 Message-ID: References: <1305771744-83951-1-git-send-email-tsunanet@gmail.com> <20110518.223622.1525088601595365235.davem@davemloft.net> <20110519.001426.2119532755281545481.davem@davemloft.net> <9DC9A4D5-8E16-4361-B323-C92D563171A1@comsys.rwth-aachen.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: David Miller , kuznet@ms2.inr.ac.ru, pekkas@netcore.fi, jmorris@namei.org, yoshfuji@linux-ipv6.org, kaber@trash.net, hagen@jauu.net, eric.dumazet@gmail.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Alexander Zimmermann Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Wed, May 18, 2011 at 11:36 PM, Alexander Zimmermann wrote: > If you set the initRTO=0.1s, it's good for me but bad for the rest of the > world. That's the difference. > > Or do you want to implement a lower barrier of 1sec so that you can ensure > that nobody set the initRTO lower than 1s? Oh, I see. Yes, there is a lower bound (and an upper bound) on what values the kernel will accept as initRTO. In the patch "Implement a two-level initial RTO as per draft RFC 2988bis-02" above, I re-used TCP_RTO_MIN and TCP_RTO_MAX in net/ipv4/sysctl_net_ipv4.c in order to prevent users from setting a minRTO that's outside this range. They are defined as follows in tcp.h: #define TCP_RTO_MAX ((unsigned)(120*HZ)) #define TCP_RTO_MIN ((unsigned)(HZ/5)) So we're talking about a [200ms ; 120s] range no matter what. -- Benoit "tsuna" Sigoure Software Engineer @ www.StumbleUpon.com