From owner-freebsd-questions@FreeBSD.ORG Tue Dec 13 08:44:56 2005 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 3D20616A41F for ; Tue, 13 Dec 2005 08:44:56 +0000 (GMT) (envelope-from tedm@toybox.placo.com) Received: from mail.freebsd-corp-net-guide.com (mail.web-strider.com [65.75.192.90]) by mx1.FreeBSD.org (Postfix) with ESMTP id 7970743D4C for ; Tue, 13 Dec 2005 08:44:55 +0000 (GMT) (envelope-from tedm@toybox.placo.com) Received: from tedwin2k (nat-rtr.freebsd-corp-net-guide.com [65.75.197.130]) by mail.freebsd-corp-net-guide.com (8.11.1/8.11.1) with SMTP id jBD8lmb99106; Tue, 13 Dec 2005 00:47:48 -0800 (PST) (envelope-from tedm@toybox.placo.com) From: "Ted Mittelstaedt" To: "Drew Tomlinson" Date: Tue, 13 Dec 2005 00:44:35 -0800 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.6604 (9.0.2911.0) In-Reply-To: <439DDDDB.2080902@mykitchentable.net> Importance: Normal X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1506 Cc: Michael Vince , danial_thom@yahoo.com, freebsd-questions@freebsd.org, Kris Kennaway Subject: RE: Polling For 100 mbps Connections? (Was Re: Freebsd Theme Song) X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 13 Dec 2005 08:44:56 -0000 >-----Original Message----- >From: Drew Tomlinson [mailto:drew@mykitchentable.net] >Sent: Monday, December 12, 2005 12:30 PM >To: Ted Mittelstaedt >Cc: Michael Vince; danial_thom@yahoo.com; freebsd-questions@freebsd.org; >Kris Kennaway >Subject: Polling For 100 mbps Connections? (Was Re: Freebsd Theme Song) > > >On 12/12/2005 8:13 AM Ted Mittelstaedt wrote: > >>Michael, >> >> Fundamentally, here's the problem Danial is claiming exists: >> >>it takes a certain amount of time to get the packet clocked in >>from the network into the ethernet receiver. This is hardware >>dependent and cannot be changed. >> >>It takes a certain amount of time to get the packet out of >>the hardware in the ethernet card into main ram, this also >>hardware dependent and cannot be changed. (unless the device >>driver is terribly inefficient, which we will assume it's not) >> >>Once in main ram, the information in the packet has to go through >>a number of code statements. The more code statements the >>longer the information in the packet is sitting around in >>the FreeBSD system's memory. >> >>It then takes a certain amount of time to get the information >>out of main memory into the other sending ethernet nic's buffers, >> >>and it takes time to get it out of the sending nic back to the >>wire. >> >>Danial is claiming the slowness is in the main ram section of >>things, not in the ethernet driver code. >> >>polling makes the ethernet driver more efficient at high data >>rates, but it does nothing for the speed of processing within >>the TCPIP stack itself. At low data rates polling is less >>efficient than the interrupt method. And unless the nic driver >>is terribly inefficient to start with, the time it adds to the >>packet path in the system is minor compared to the time spent >>in the TCP/IP stack. >> >>Ted >> >> > >Thanks for the explanation. So would polling be beneficial or >detrimental for a 100 mbps Ethernet card? Yes, if you were running 100Mbt's of bandwidth through it. >Not sure if 100 mbps is >considered "high" or "low" speed. I'm specifically interested in >NetGear cards using the dc driver or DLink cards using the rl driver. > The rl chipset isn't known as a very good chipset. YMMV Some of the Netgear cards use clone 21143 chipsets which are extremely inferior to the real thing. In particular if your Netgear card is using a PNIC chipset it is pretty bad with serious performance penalty. This is documented in Section 4 of the dc manpage. People seem to have good results with polling on the fxp cards. Ted