From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755254Ab3AVSm6 (ORCPT ); Tue, 22 Jan 2013 13:42:58 -0500 Received: from moutng.kundenserver.de ([212.227.17.8]:57706 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754528Ab3AVSm4 (ORCPT ); Tue, 22 Jan 2013 13:42:56 -0500 Date: Tue, 22 Jan 2013 19:42:45 +0100 From: Leandro Lucarella To: Rick Jones Cc: Eric Dumazet , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Doubts about listen backlog and tcp_max_syn_backlog Message-ID: <20130122184245.GJ4608@sociomantic.com> References: <20130122161038.GG4608@sociomantic.com> <1358873142.3464.3964.camel@edumazet-glaptop> <20130122165929.GH4608@sociomantic.com> <1358874800.3464.4002.camel@edumazet-glaptop> <50FED7CE.1030008@hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <50FED7CE.1030008@hp.com> X-Paranoid: Just because you're paranoid, don't mean they're not after you. User-Agent: Mutt/1.5.21 (2010-09-15) X-Provags-ID: V02:K0:s+Lsm4otiRxPFkhEkJO21Fzzg4pp61f0kJs1rKTpx/Z 0qDIccfSbokGu/QPN+ydpB/TG91h5f2N1myiXw+6tPiXUS0XI/ e5uB3ABeYQ4FejmKg3zlMpi/qtFlFFJmSSSXGBn6Jw1AhLXPIf fu9veSMHQ1mCZf/457Ijpt4ufl7SKLg+CNkeLpPPJlXngzHN0B lOCBUep5g/pS7xSv6L5MkRJ9oIwOQWC8+VJZqpdI2QNy3l2Tdt mZG72vvKBn9SxLuGG36qUp50OLiKqN/mqdv5dbr8YdzboTR5e6 HYqBONdvXjXfdQE6SdzLNkQjbEpj3s7KE9mgP+tegmXVbCcLMw X/Bbg0DXjOTktvwwLnng9NX8JWP1MG2PLWRyUYnVT41IQ3+iwi sLHj9JuhD+lhg== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 22, 2013 at 10:17:50AM -0800, Rick Jones wrote: > >What is important is the backlog, and I guess you didn't increase it > >properly. The somaxconn default is quite low (128) > > Leandro - > > If that is being overflowed, I believe you should be seeing something like: > > 14 SYNs to LISTEN sockets dropped > > in the output of netstat -s on the system on which the server > application is running. What is that value reporting exactly? Because we are using syncookies, and AFAIK with that enabled, all SYNs are being replied, and what the listen backlog is really limitting is the "completely established sockets waiting to be accepted", according to listen(2). What I don't really know to be honest, is what a "completely established socket" is, does it mean that the SYN,ACK was sent, or the ACK was received back? Also, from the client side, when is the connect(2) call done? When the SYN,ACK is received? Thanks! -- Leandro Lucarella sociomantic labs GmbH http://www.sociomantic.com