From owner-freebsd-current@FreeBSD.ORG Tue Mar 18 13:59:59 2008 Return-Path: Delivered-To: freebsd-current@FreeBSD.ORG Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D8350106566B for ; Tue, 18 Mar 2008 13:59:59 +0000 (UTC) (envelope-from olli@lurza.secnetix.de) Received: from lurza.secnetix.de (unknown [IPv6:2a01:170:102f::2]) by mx1.freebsd.org (Postfix) with ESMTP id 5CC0B8FC13 for ; Tue, 18 Mar 2008 13:59:59 +0000 (UTC) (envelope-from olli@lurza.secnetix.de) Received: from lurza.secnetix.de (localhost [127.0.0.1]) by lurza.secnetix.de (8.14.1/8.14.1) with ESMTP id m2IDxqTs017639; Tue, 18 Mar 2008 14:59:57 +0100 (CET) (envelope-from oliver.fromme@secnetix.de) Received: (from olli@localhost) by lurza.secnetix.de (8.14.1/8.14.1/Submit) id m2IDxpdW017638; Tue, 18 Mar 2008 14:59:51 +0100 (CET) (envelope-from olli) Date: Tue, 18 Mar 2008 14:59:51 +0100 (CET) Message-Id: <200803181359.m2IDxpdW017638@lurza.secnetix.de> From: Oliver Fromme To: freebsd-current@FreeBSD.ORG, vadim_nuclight@mail.ru In-Reply-To: X-Newsgroups: list.freebsd-current User-Agent: tin/1.8.3-20070201 ("Scotasay") (UNIX) (FreeBSD/6.2-STABLE-20070808 (i386)) MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.1.2 (lurza.secnetix.de [127.0.0.1]); Tue, 18 Mar 2008 14:59:58 +0100 (CET) Cc: Subject: Re: RELEASE discs & ISO images (for future) X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: freebsd-current@FreeBSD.ORG, vadim_nuclight@mail.ru List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 18 Mar 2008 13:59:59 -0000 Vadim Goncharov wrote: > Oliver Fromme wrote: > > [...] > > > > 224655360 7.0-RELEASE-i386-livefs.iso > > > > 94493696 7.0-RELEASE-i386-livefs.iso.uzip (16k cluster) > > > > 110188032 7.0-RELEASE-i386-livefs.iso.uzip (2K cluster) > > > > > > > > So the difference is 124 MB for 16K cluster size, and > > > > 109 MB for 2K cluster size (which is noticably faster > > > > during access). Actually the space savings will be a > > > > bit less, because the /boot directory (about 30 MB) > > > > won't be compressed. So the real gain is probably a > > > > little less than 100 MB in the 2K case. > > > > > > By the way, the maxmum cluster size is 127k or 130048 with uzip, > > > if you want to maximize the compression ratio. > > That would make the live FS painfully slow, and it wouldn't > > make a big difference from the default (16K). > > It is already noticeably slow with the default cluster size > > of 16K on my test machine (a 1 GHz VIA C3), so would rather > > prefer to use 2K cluster size, even though compression will > > be not quite as good. (2K is the minimum, less than that > > doesn't make sense for CD9660 media because the physical > > sector size is 2K.) > > How much is slowdown from 2K to 16K ? It's very noticeable. I haven't done benchmarks, but you can clearly feel the difference. A find(1) takes more time. Also man(1) takes longer until the page comes up. Any kind of random access is slower, unless all data is already cached. Interestingly there doesn't seem to be a difference between 2K and 4K, and the difference to 8K is only very small. But there is a noticeable difference between 8K and 16K. I don't know why, maybe it's related to FreeBSD's handling of FS buffers. So maybe the "optimal" cluster size for an acceptable performance/compression ratio would be 8K. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M. Handelsregister: Registergericht Muenchen, HRA 74606, Geschäftsfuehrung: secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün- chen, HRB 125758, Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart FreeBSD-Dienstleistungen, -Produkte und mehr: http://www.secnetix.de/bsd "Documentation is like sex; when it's good, it's very, very good, and when it's bad, it's better than nothing." -- Dick Brandon