From owner-cvs-all Wed Dec 1 15:40:25 1999 Delivered-To: cvs-all@freebsd.org Received: from alpo.whistle.com (alpo.whistle.com [207.76.204.38]) by hub.freebsd.org (Postfix) with ESMTP id 2C847151DF; Wed, 1 Dec 1999 15:40:17 -0800 (PST) (envelope-from julian@whistle.com) Received: from current1.whiste.com (current1.whistle.com [207.76.205.22]) by alpo.whistle.com (8.9.1a/8.9.1) with ESMTP id PAA36343; Wed, 1 Dec 1999 15:39:28 -0800 (PST) Date: Wed, 1 Dec 1999 15:39:28 -0800 (PST) From: Julian Elischer To: Archie Cobbs Cc: "Justin T. Gibbs" , cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/kern uipc_mbuf.c src/sys/sys mbuf.h In-Reply-To: <199912012327.PAA45003@bubba.whistle.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-cvs-all@FreeBSD.ORG Precedence: bulk basically it's not supposed to be in the hot path. It's for debugging and tracing utilities. On Wed, 1 Dec 1999, Archie Cobbs wrote: > Justin T. Gibbs writes: > > > Modified files: > > > sys/kern uipc_mbuf.c > > > sys/sys mbuf.h > > > Log: > > > The functions m_copym() and m_copypacket() return read-only copies, > > > because in the case of mbuf clusters they only increment the reference > > > count rather than actually copying the data. > > > > > > Add comments to this effect, and add a new routine called m_dup() that > > > returns a real, writable copy of an mbuf chain. > > > > How does this work in a 0 copy system? > > Not sure what a '0 copy system' is.. > > Basically all it does is create a completely new mbuf chain containing > the same data as the original. Definitely at least 1 copy :-) > > You rarely need this, but 'ipfw tee' is one of those cases. > > -Archie > > ___________________________________________________________________________ > Archie Cobbs * Whistle Communications, Inc. * http://www.whistle.com > > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message