From owner-freebsd-hackers Sun Apr 12 21:58:56 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id VAA04665 for freebsd-hackers-outgoing; Sun, 12 Apr 1998 21:58:56 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from gatekeeper.alcatel.com.au (gatekeeper.alcatel.com.au [203.17.66.1]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id VAA04659 for ; Sun, 12 Apr 1998 21:58:50 -0700 (PDT) (envelope-from Peter.Jeremy@alcatel.com.au) Received: from mfg1.cim.alcatel.com.au ([139.188.23.1]) by gatekeeper.alcatel.com.au (PMDF V5.1-7 #U2695) with ESMTP id <01IVTP8V36XS000IW9@gatekeeper.alcatel.com.au> for freebsd-hackers@freebsd.org; Mon, 13 Apr 1998 14:58:16 +1000 Received: from cbd.alcatel.com.au by cim.alcatel.com.au (PMDF V5.1-10 #U2695) with ESMTP id <01IVTP8T7CTCB4TJ8V@cim.alcatel.com.au> for freebsd-hackers@freebsd.org; Mon, 13 Apr 1998 14:58:14 +1000 Received: from gsms01.alcatel.com.au by cbd.alcatel.com.au (PMDF V5.1-7 #U2695) with ESMTP id <01IVTP8QRK4GAZTR43@cbd.alcatel.com.au> for freebsd-hackers@freebsd.org; Mon, 13 Apr 1998 14:58:10 +1100 Received: (from jeremyp@localhost) by gsms01.alcatel.com.au (8.8.8/8.7.3) id OAA04968 for freebsd-hackers@freebsd.org; Mon, 13 Apr 1998 14:58:09 +1000 (EST) Date: Mon, 13 Apr 1998 14:58:09 +1000 (EST) From: Peter Jeremy Subject: Waste space in kernel data structures To: freebsd-hackers@FreeBSD.ORG Message-id: <199804130458.OAA04968@gsms01.alcatel.com.au> Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG I have noticed a couple of cases in the 2.x kernel where data structures (particularly private device driver structures) have been laid out without due consideration for alignment requirements - resulting in assorted padding bytes. In addition, the standard `boolean' type is a char - which is mostly wasted. Has anyone looked at how much kernel memory space is wasted by compiler padding and felt that it would be worthwhile doing a cleanup? Has anyone looked at whether the data space that could be saved by converting boolean flags to a single bit outweighs the speed loss and possible code bloat? Peter -- Peter Jeremy (VK2PJ) peter.jeremy@alcatel.com.au Alcatel Australia Limited 41 Mandible St Phone: +61 2 9690 5019 ALEXANDRIA NSW 2015 Fax: +61 2 9690 5247 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message