From owner-freebsd-hackers Sun Mar 14 1:29:58 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from rah.star-gate.com (rah.star-gate.com [209.249.129.138]) by hub.freebsd.org (Postfix) with ESMTP id 6506A14F33 for ; Sun, 14 Mar 1999 01:28:55 -0800 (PST) (envelope-from hasty@rah.star-gate.com) Received: from rah.star-gate.com (localhost.star-gate.com [127.0.0.1]) by rah.star-gate.com (8.9.1/8.8.8) with ESMTP id BAA85633; Sun, 14 Mar 1999 01:27:49 -0800 (PST) (envelope-from hasty@rah.star-gate.com) Message-Id: <199903140927.BAA85633@rah.star-gate.com> X-Mailer: exmh version 2.0.2 2/24/98 To: Matthew Dillon Cc: Wes Peters , Cory Kempf , Bill Paul , freebsd-hackers@FreeBSD.ORG Subject: Re: Gigabit ethernet -- what am I doing wrong? In-reply-to: Your message of "Sun, 14 Mar 1999 00:42:25 PST." <199903140842.AAA89134@apollo.backplane.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Sun, 14 Mar 1999 01:27:49 -0800 From: Amancio Hasty Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > Most network cards must DMA into main memory -- card-to-card transfers > cannot be done. So routing a single packet requires the data to flow > over the PCI bus twice. The 132 MBytes/sec become 66 MBytes/sec right > off the bat. I am not sure that I can follow you here . Most PCI cards which are capable of doing dma to the host system's memory can do card - to - card transfer ;however, the target "card" most be able to use the stored data in the case of a network card it must have memory to receive the pack or a very elaborate protocol to accept short dma bursts which it can then process. Amancio To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message