From owner-cvs-all Tue Jul 27 1:15:32 1999 Delivered-To: cvs-all@freebsd.org Received: from dingo.cdrom.com (castles554.castles.com [208.214.165.118]) by hub.freebsd.org (Postfix) with ESMTP id 35BE214E44; Tue, 27 Jul 1999 01:15:24 -0700 (PDT) (envelope-from mike@dingo.cdrom.com) Received: from dingo.cdrom.com (LOCALHOST [127.0.0.1]) by dingo.cdrom.com (8.9.3/8.8.8) with ESMTP id BAA01282; Tue, 27 Jul 1999 01:10:24 -0700 (PDT) (envelope-from mike@dingo.cdrom.com) Message-Id: <199907270810.BAA01282@dingo.cdrom.com> X-Mailer: exmh version 2.0.2 2/24/98 To: "Justin T. Gibbs" Cc: Mike Smith , "Justin T. Gibbs" , cvs-all@FreeBSD.org, cvs-committers@FreeBSD.org Subject: Re: cvs commit: src/release/sysinstall tcpip.c In-reply-to: Your message of "Fri, 23 Jul 1999 11:43:44 MDT." <199907231743.LAA12993@caspian.plutotech.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Tue, 27 Jul 1999 01:10:24 -0700 From: Mike Smith Sender: owner-cvs-all@FreeBSD.ORG Precedence: bulk > >> In zero copy applications, the header and the payload are usually placed > >> in separate areas. > > > >Can you elaborate on this a little? We don't support the two being in > >a separate allocation unit at the moment, yet I understood the 'fast > >forwarding' code was essentially a zero-copy operation. > > I have not looked at the code Drew Gallatin used for his myrinet work, > but here at Pluto, we plan to ship the header information into CPU > memory and the payload to another PCI device's memory. I would expect > a similar approach to be used for page flipping packet payloads into > user space in more conventional zero-copy applications. Hmm. Would you be using a second mbuf with external storage pointing to the other device's memory to account for the payload? Is this a short-circuit routing technique, or just immediate delivery of payload data? Who unpacks the data that's going to the target peripheral? -- \\ The mind's the standard \\ Mike Smith \\ of the man. \\ msmith@freebsd.org \\ -- Joseph Merrick \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message