From owner-freebsd-current Sun Nov 24 0:38:42 2002 Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id DC11F37B401; Sun, 24 Nov 2002 00:38:41 -0800 (PST) Received: from rwcrmhc52.attbi.com (rwcrmhc52.attbi.com [216.148.227.88]) by mx1.FreeBSD.org (Postfix) with ESMTP id 63B4443E91; Sun, 24 Nov 2002 00:38:41 -0800 (PST) (envelope-from julian@elischer.org) Received: from InterJet.elischer.org (12-232-168-4.client.attbi.com[12.232.168.4]) by rwcrmhc52.attbi.com (rwcrmhc52) with ESMTP id <2002112408383005200etq2ue>; Sun, 24 Nov 2002 08:38:30 +0000 Received: from localhost (localhost.elischer.org [127.0.0.1]) by InterJet.elischer.org (8.9.1a/8.9.1) with ESMTP id AAA29658; Sun, 24 Nov 2002 00:37:05 -0800 (PST) Date: Sun, 24 Nov 2002 00:37:03 -0800 (PST) From: Julian Elischer To: Andrew Gallatin Cc: Robert Watson , Luigi Rizzo , current@freebsd.org Subject: Re: mbuf header bloat ? In-Reply-To: <15840.8629.324788.887872@grasshopper.cs.duke.edu> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Sat, 23 Nov 2002, Andrew Gallatin wrote: > > As you eloquently state, there are a number of tradeoffs involved. On > a 64-bit platform, 99% of users are paying 40 bytes/pkt for something > that they will never use. On x86, 99.99% of users are paying 20 > bytes/pkt for a feature they will never use. At least a signifigant > fraction of nics make use of csum offloading (xl, ti, bge, em, myri). the downside to the TAG stuff is that you need to allocate a separate tag storage, and that is a malloc.. which has certain characteristics vs the mbuf allocator. We have a special allocator for mbufs for a reason. (I'm not sure how many of the original reasons still apply). so it's worth looking at whether malloc is a suitable method of allocating all that stuff before we take it out of the mbuf. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message