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Date: Sun, 14 Feb 2010 01:33:22 -0800 From: "Justin P. Mattock" <justinmattock@...il.com> To: Jean Delvare <khali@...ux-fr.org> CC: Phillip Lougher <phillip@...gher.demon.co.uk>, lasse.collin@...aani.org, linux-kernel <linux-kernel@...r.kernel.org>, mirrors@...nel.org, users@...nel.org, "FTPAdmin Kernel.org" <ftpadmin@...nel.org>, Pavel Machek <pavel@....cz> Subject: Re: [kernel.org users] XZ Migration discussion On 02/14/10 01:23, Jean Delvare wrote: > On Sat, 13 Feb 2010 23:52:17 +0000, Phillip Lougher wrote: >> Jean Delvare wrote: >> >>> >>> Compared to bz2, gz saves... 2% on the overall time. As a conclusion, I >>> think we can plain discard the argument "I need .gz because my machine >>> is slow" from now on. It simply doesn't hold. >>> >> >> I agree, but, IMHO the main argument for keeping .gz is cross-platform >> availability and wide language support, not hardware limitations. Doing >> a quick google brings up .gz interfaces for every language you can think >> of (C, Java, Perl, Python, TCL etc.), not to mention complete separate >> implementations in Java and Pascal (not just wrappers on top of the zlib >> library), and probably more. >> >> With xz you have just one C/C++ implementation with a single library with >> an undocumented API for C/C++ programmers. > > This can probably be easily explained. gz is very fast decompressing so > it is a very good choice for transparent decompression of files which > must be accessible fast but aren't used frequently. Manual pages or > printer drivers come to mind. bz2 and lzma, OTOH, are meant for longer > term archiving. Their compression ratio benefit is only worth it for > larger files that you don't access that frequently. > > I am not claiming that gzip is dead. It is very useful and it is there > to stay for the years to come, no doubt about that. What I'm saying is > that it isn't the best choice for large files to be downloaded from a > remote server. > >> It may be a slight stretch of the imagination, but with with .gz you can >> conceive programmers writing programs to download a .gz from kernel.org and >> decompressing/searching it, in almost any language of choice. With the JAVA >> implementation .gz is genuinely cross platform and you don't need glibc/ >> C++ compilers, just a Java VM. Contrast with xz, where if the xz utility >> isn't available, or doesn't do what you want, you're stuck with programming >> in C/C++ with all the baggage that entails. > > Honestly, I don't think we care at all when it comes to the kernel.org > files. Accessing individual files inside a compressed kernel tarball > without first expanding it entirely would be horribly slow and > unpractical, no matter which compression format was used. I can't think > of any case where you won't unpack the tarball first, and for this task > an external tool will do just fine. > > And, once again, there are several public instances of gitweb and LXR > available if you only want to browse the code. > just out of curiosity what would happen if by say I take a file and turn it into .gz then turn the .gz into .xz or vice versa? so at the end of the day you have a list of .gz's(or whatever), then expending on the type(.gz,.bz2,etc..) unpackage and voila either a tree or some other compressed file(.bz2,xz, or .gz). just thinking out loud(so don't shoot me please). Justin P. Mattock -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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