From owner-freebsd-net@FreeBSD.ORG Tue Apr 1 10:42:47 2008 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 78582106566B for ; Tue, 1 Apr 2008 10:42:47 +0000 (UTC) (envelope-from rpaulo@gmail.com) Received: from ug-out-1314.google.com (ug-out-1314.google.com [66.249.92.173]) by mx1.freebsd.org (Postfix) with ESMTP id F02048FC13 for ; Tue, 1 Apr 2008 10:42:46 +0000 (UTC) (envelope-from rpaulo@gmail.com) Received: by ug-out-1314.google.com with SMTP id y2so75330uge.37 for ; Tue, 01 Apr 2008 03:42:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:date:from:to:cc:subject:message-id:references:mime-version:content-type:content-disposition:in-reply-to:user-agent:sender; bh=Mg2EoIw3Bn9zqeuLrD/DOi5Q9WiJADfVrdvtzLegDLU=; b=XXKpajZ6JbRpjUdrjIgxX5rkhkkbsL2vkjAi/LC8/PbkgrWdT27KxA8tc2i0kuoQK/4aQHDdiWTpxtqO5K/AkI3J5CaPox/pAEtYaav5VonEzwjBTXlzrm9PAu4OyqRRMlteGrbawBluDiIrNC1xvAyMRi2B/dMC+nZbF2+7oNg= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version:content-type:content-disposition:in-reply-to:user-agent:sender; b=PCn82L/isERc2o5gMbYCVW3G4q8iF0iVhJpRqX/WzEx8OEohX4Qt0JFpOpN7NvE8loh2vmBqHaitRwV1XQUAnKIDrisjTa4rKfZNqHskVpYzagWJdfr1ur6QdNYE/aGoT17j8b6nD069GddmV2LXpyiWUT+l4yb43xg5q8XUOg0= Received: by 10.67.30.3 with SMTP id h3mr284034ugj.35.1207046565656; Tue, 01 Apr 2008 03:42:45 -0700 (PDT) Received: from fnop.net ( [89.214.129.156]) by mx.google.com with ESMTPS id j4sm245284ugf.49.2008.04.01.03.42.42 (version=SSLv3 cipher=OTHER); Tue, 01 Apr 2008 03:42:44 -0700 (PDT) Date: Tue, 1 Apr 2008 11:41:29 +0100 From: Rui Paulo To: Anthony Pankov Message-ID: <20080401104128.GA1194@fnop.net> References: <1333421734.20080328201458@mail.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1333421734.20080328201458@mail.ru> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: Rui Paulo Cc: freebsd-net@freebsd.org, performance@freebsd.org Subject: Re: packet delay because of blackhole X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 01 Apr 2008 10:42:47 -0000 On Fri, Mar 28, 2008 at 08:14:58PM +0300, Anthony Pankov wrote: > Just for somebody convince. > > While analyzing client<->server HTTPS conversation one second delay in > packet exchange was discovered (strongly reproducible): > > Sample: > N time > 6 0.002303 10.28.4.14 10.28.4.50 SSL Client Hello > 7 0.106710 10.28.4.50 10.28.4.14 TCP 443 > 1447 [ACK] Seq=1 Ack=103 Win=65535 Len=0 > 8 1.045712 10.28.4.50 10.28.4.14 TLSv1 Server Hello, Certificate, Server Hello Done > > Another sample: > 10 0.011722 10.28.4.14 10.28.4.50 TLSv1 Application Data > 11 0.115933 10.28.4.50 10.28.4.14 TCP 443 > 1442 [ACK] Seq=839 Ack=519 Win=65466 Len=0 > 12 1.054037 10.28.4.50 10.28.4.14 TLSv1 Application Data > > The reason for delay is sysctl tcp.blackhole value grater than 0, much to surprise. > > So, turning tcp.blackhole to 0 eliminate any delay (strongly reproducible). > > System: FreeBSD 6_2_stable I'm not sure how performance penalty can induce a cache miss and I it's very processor specific. So, you're best guess is to profile the kernel. Regards, -- Rui Paulo