В Mon, 12 May 2014 14:17:11 +0200
Tom Wijsman <tom...@gentoo.org> пишет:
> On Mon, 12 May 2014 14:47:36 +0400
> Alexander Tsoy <alexan...@tsoy.me> wrote:
>
> > Here is my test results. xz options: "--lzma2=preset=6e,dict=4MiB".
> > Larger dictionary size does not improve compression ratio, I get
> > even worse results with just "-6e" or "-9e". man-bz2 is a full copy of
> > my /usr/share/man, man-xz is a recompressed one.
>
> Picking a random post to reply; if you don't already, please consider
> to do these tests in tmpfs to cancel out any fs / storage differences.
>
The same test in tmpfs.
$ time find man-bz2/ -type f -name "*.bz2" -exec bzcat '{}' > /dev/null \;
real 0m35.895s
user 0m14.232s
sys 0m14.121s
$ time find man-xz/ -type f -name "*.xz" -exec xzcat '{}' > /dev/null \;
real 0m44.342s
user 0m16.842s
sys 0m21.459s
And here is additional test. It shows where is actually a bottleneck.
xz is faster in decompression, but looks like it just has a slower
process initialization speed. So it's slower in decompressing of a single
little file.
$ time find man-bz2/ -type f -name "*.bz2" -exec bzcat '{}' > /dev/null \+
real 0m10.096s
user 0m9.000s
sys 0m0.787s
$ time find man-xz/ -type f -name "*.xz" -exec xzcat '{}' > /dev/null \+
real 0m7.846s
user 0m7.108s
sys 0m0.487s
--
Alexander Tsoy
