On Fri, Oct 8, 2010 at 2:01 AM, Matthias Klose <d...@ubuntu.com> wrote: >> Also, there are 12MB of jar files, which are basically zip files. We >> can also shrink those by 5MB or so with advzip, but that doesn't seem >> to shrink a .tgz of them so it may not shrink the liveCD. Since zip >> files compress file by file, we may be able to save space on the >> liveCD by running "advzip -z -0" on them. That would expand them to >> 24MB, but reduces the size of a .tgz of them to 4.6MB, possibly saving >> space on the liveCD if squashfs is similarly efficient. > > how does OOo behave with the repacked zip file? is it faster, slower, does it
No, I made a script to open oowriter 100 times. It didn't find any consistent difference in performance. > need more memory when it runs? imo, changes like this should be integrated > into gzip needs less than 1MB to decode (or even encode). The effect on memory usage is likely to be minimal. http://tukaani.org/lzma/benchmarks.html > the package build process, and sent upstream. patches welcome. > > same for jar files. are these extracted as fast as without your changes by the > jvm? if not, then these should be left alone (and afaik there shouldn't be any > jar files on the live CD). FYI, most of the jar files come from firefox and openoffice. Firefox refuses to start without these jar files. I doubt they are used by a jvm. Using the 7z deflate instead of gzip shouldn't harm decompression time. In fact, it should improve speed slightly because there is less compressed input to parse (If I tar up /etc and compress it with gzip and advdef, the one compressed with advdev does in fact seem to gunzip very slightly faster). The other question is does compressing decompressed jars (or visa-versa) affect performance. A atom based netbook with a rotational disk seemed like a good machine to test on as it is towards the low end of performance. Repeatedly running oowriter and firefox ten times did not lead to and consistent performance differences (see attaced timeopen.ar). If there is any difference it would be within a few percent. This suggests that we can decompress them (to save liveCD space), or compress them (to save installed space) without having much effect on performance. It is also plausible that decompressing the jars saves installed space on 'Btrfs -o compress' filesystems, but I have not tested whether Btrfs compression heuristics automatically detect the jars as being compressible. -- John C. McCabe-Dansted
timeopen.ar
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