Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756585Ab0BPOAO (ORCPT ); Tue, 16 Feb 2010 09:00:14 -0500 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:34728 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756176Ab0BPOAL (ORCPT ); Tue, 16 Feb 2010 09:00:11 -0500 Date: Tue, 16 Feb 2010 15:00:04 +0100 From: Pavel Machek To: Jean Delvare Cc: mirrors@kernel.org, lasse.collin@tukaani.org, linux-kernel , users@kernel.org, "FTPAdmin Kernel.org" , Linus Torvalds , Willy Tarreau Subject: Re: [kernel.org users] XZ Migration discussion Message-ID: <20100216140004.GB4821@elf.ucw.cz> References: <4B744E13.8040004@kernel.org> <20100212150137.648dca7c@hyperion.delvare> <4B75A5DC.3060803@kernel.org> <20100212202357.6363d5af@hyperion.delvare> <20100212230702.GA10266@1wt.eu> <20100213091748.276821e1@hyperion.delvare> <20100214170724.GE1578@ucw.cz> <20100214200803.4b2348ce@hyperion.delvare> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100214200803.4b2348ce@hyperion.delvare> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3027 Lines: 68 > > > I have an old, slow machine here which I am going to use to perform > > > some real world testing, and I'll post the results when I'm done. But I > > > suspect that building a kernel on this machine, even a small one with > > > just the drivers it needs, will take much longer than unpacking the > > > sources. So anyone worrying about performance would rather rely on > > > cross-compilation, and in turn can afford whatever decompression tool > > > is needed. > > > > On zaurus, kernel compilation takes 4 hours. (I.e. "one night"). So > > that one is ... well ... done overnight. > > Out of curiosity, if it takes that long, why don't you use a > cross-compiler? Because I hack it on the go. First build is long and ugly, but subsequent builds only take 5 minutes or so, so development is possible. (If I crosscompiled it, I'd have to crosscompile even the subsequent builds, which is impossible -- no powerful machine nearby). > > Untar is something I normally wait for, since you need to run > > (interactive) oldconfig after that. > > You'll have to wait, no matter what compression format you use (and > even if you don't compress the tarball). Judging by the duration of the > build on your machine, I'd estimate the decompression time to 7 minutes > for gz vs. 15 minutes for bz2 maybe? I doubt you sit in front of the > machine for 7 minutes waiting for tar.gz to decompress, right? So I > fail to see what difference it makes. You'll just do something else for > 15 minutes instead of doing something else for 7 minutes. Actually I do sit in front of the machine, reading mails while it decompresses. [I'll get some numbers.] sh-3.2$ time bzip2 -d < ~/.ketchup/l^Ginux-2.6.31.tar.bz2 > delme.tar 485.73user 137.35system 683.32 (11m23.320s) elapsed 91.18%CPU sh-3.2$ df -h^H^H^H^H^Htime cat delme.tar > /usr/src/delme.tar 0.57user 109.03system 381.13 (6m21.133s) elapsed 28.75%CPU sh-3.2$ time zca^G^Gt delme.tar > /u ^H^H ^H^H ^H^H ^H^Hdelme.tar.gz ^H^H ^H^H ^H^H +^H^H ^H^H ^H^H ^H^H ^H^H ^H^H ^H^H ^H^H ^H^H ^H^H.gz > delme.tar 43.97user 106.22system 223.26 (3m43.261s) elapsed 67.27%CPU So... gzip is actually _faster_ than uncompressed data, while bzip is twice slower. Don't know about xzip. Anyway, gzip just makes sense. It is both smaller and faster than alternatives, and nearly as portable. > Anyway, as I have been saying several times already, nothing prevents > you from repacking tarballs to gz before uploading it to your slow > system if such is your desire. I can understand the portability > argument, but the decompression time, no way. Ok, so lets go by the portability argument. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/