Date: Tue, 27 Jul 1999 01:10:24 -0700 From: Mike Smith <mike@smith.net.au> To: "Justin T. Gibbs" <gibbs@caspian.plutotech.com> Cc: Mike Smith <mike@smith.net.au>, "Justin T. Gibbs" <gibbs@plutotech.com>, cvs-all@FreeBSD.org, cvs-committers@FreeBSD.org Subject: Re: cvs commit: src/release/sysinstall tcpip.c Message-ID: <199907270810.BAA01282@dingo.cdrom.com> In-Reply-To: Your message of "Fri, 23 Jul 1999 11:43:44 MDT." <199907231743.LAA12993@caspian.plutotech.com>
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> >> 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
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