From owner-freebsd-hackers@FreeBSD.ORG Fri Feb 19 18:39:36 2010 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 0A10A1065670 for ; Fri, 19 Feb 2010 18:39:36 +0000 (UTC) (envelope-from joerg@britannica.bec.de) Received: from www.sonnenberger.org (www.sonnenberger.org [92.79.50.50]) by mx1.freebsd.org (Postfix) with ESMTP id BE6878FC0C for ; Fri, 19 Feb 2010 18:39:35 +0000 (UTC) Received: from britannica.bec.de (www.sonnenberger.org [192.168.1.10]) by www.sonnenberger.org (Postfix) with ESMTP id 1F9E066790 for ; Fri, 19 Feb 2010 19:39:33 +0100 (CET) Received: by britannica.bec.de (Postfix, from userid 1000) id F1E1315C6C; Fri, 19 Feb 2010 19:39:01 +0100 (CET) Date: Fri, 19 Feb 2010 19:39:01 +0100 From: Joerg Sonnenberger To: freebsd-hackers@freebsd.org Message-ID: <20100219183901.GA11388@britannica.bec.de> Mail-Followup-To: freebsd-hackers@freebsd.org References: <20100217215940.GA19713@triton8.kn-bremen.de> <4B7CE066.4030403@freebsd.org> <20100218183459.GA65508@triton8.kn-bremen.de> <20100218191347.GA4040@britannica.bec.de> <4B7E1BA5.7050209@freebsd.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4B7E1BA5.7050209@freebsd.org> User-Agent: Mutt/1.5.20 (2009-06-14) Subject: Re: "tar tfv /dev/cd0" speedup patch X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 19 Feb 2010 18:39:36 -0000 On Thu, Feb 18, 2010 at 09:03:33PM -0800, Tim Kientzle wrote: > Joerg Sonnenberger wrote: > >On Thu, Feb 18, 2010 at 07:34:59PM +0100, Juergen Lock wrote: > >> Ok here is a new version of the patch with these things fixed and the > >>Linux case added: (Linux case not tested yet, and yes I did this on > >>stable/8.) > > > >Why the check at all? Shouldn't devices that don't allow seek fail that? > >E.g. for devices, just try to seek ahead and fallback to normal reading? > > That was the initial implementation in libarchive, but > I had a number of reports of that not working for > tape drives. I recently dug out and connected an > old DDS drive I had in the closet, so I should > probably try again and see if I misunderstood > something along the way. I can think of some complications that for block devices the seek is to be a multiple of the block size (just like reads), but that's all I can think of in terms of portable problems. Joerg