From owner-freebsd-questions Sun Feb 17 11: 4: 2 2002 Delivered-To: freebsd-questions@freebsd.org Received: from acl.lanl.gov (acl.lanl.gov [128.165.147.1]) by hub.freebsd.org (Postfix) with SMTP id 5A12C37B417 for ; Sun, 17 Feb 2002 11:03:54 -0800 (PST) Received: (qmail 1705325 invoked from network); 17 Feb 2002 12:03:53 -0700 Received: from xed.acl.lanl.gov (128.165.147.191) by acl.lanl.gov with SMTP; 17 Feb 2002 12:03:53 -0700 Received: (qmail 5223 invoked by uid 3499); 17 Feb 2002 12:03:53 -0700 Received: from localhost (sendmail-bs@127.0.0.1) by localhost with SMTP; 17 Feb 2002 12:03:53 -0700 Date: Sun, 17 Feb 2002 12:03:53 -0700 (MST) From: Ronald G Minnich X-X-Sender: To: Cc: Subject: Re: in-kernel HTTP Server for FreeBSD? In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On 17 Feb 2002, Dag-Erling Smorgrav wrote: > Roy Sigurd Karlsbakk writes: > > > sendfile() isn't zero-copy, it's just two-less-copies. > > zero-copy means "zero copy-operations within memory" > > To an MCSE, maybe. I think Roy is right. AFAIK the term "zero copy" was invented by Van Jacobsen ca. 1990 to describe an optimized TCP stack he had working with the Witless interface project he did with HP, while he was still at LBL. Witless was an FDDI interface with interesting properties -- still well worth studying today. And, there was one copy in the TCP for Witless. You had to read "zero copy" to mean "Zero copies more than the absolute minimum". When we did the MINI interface at the SRC (ca. 1994), which had one less copy than Witless, we jokingly called it a "-1 copy" interface. ron To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message