Path: utzoo!mnetor!uunet!husc6!cmcl2!brl-adm!brl-smoke!gwyn
From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: comp.unix.wizards
Subject: Re: STREAMS overhead (was: SVR3.0 vs BSD4.3)
Message-ID: <7526@brl-smoke.ARPA>
Date: 22 Mar 88 23:30:40 GMT
References: <12414@brl-adm.ARPA> <4361@megaron.arizona.edu> <7499@brl-smoke.ARPA> <20768@bu-cs.BU.EDU> <7511@brl-smoke.ARPA> <4441@megaron.arizona.edu>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 11

In article <4441@megaron.arizona.edu> lm@megaron.arizona.edu.UUCP (Larry McVoy) writes:
>(It should be obvious but I'll drive it home:  the streams code that I've
>seen copies the data out of the upper level buffer and then into the 
>lower level buffer [assuming "downward" movement].

The only data copy that should normally take place is between user-mode
data space and the nearest streams buffer, also between the farther
streams buffer and the net device.  Streams module-to-module data
transfer should occur by transferring packet pointers whenever possible.
(I haven't examined SVR3 code to see if this is how it typically does
things.)