unlzma is 4 times slower than gunzip
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
lzma (Ubuntu) |
New
|
Undecided
|
Unassigned |
Bug Description
Binary package hint: lzma
I made a test with the font file /usr/share/
The compression ration is better with lzma than gzip as expected:
-----
j@j-desktop:~$ cp /usr/share/
j@j-desktop:~$ gunzip 18x18ko.pcf.gz
j@j-desktop:~$ gzip --best -c 18x18ko.pcf > 18x18ko.pcf.gz
j@j-desktop:~$ lzma --best -c 18x18ko.pcf > 18x18ko.pcf.lzma
j@j-desktop:~$ du 18x18ko.pcf*
2924 18x18ko.pcf
716 18x18ko.pcf.gz
376 18x18ko.pcf.lzma
j@j-desktop:~$
-----
However the lzma decompression seems more than 4 times slowerfor the same uncompressed original file:
-----
j@j-desktop:~$ time { for i in {0..999}; do gunzip -c 18x18ko.pcf.gz > /dev/null ; done }
real 0m38.506s
user 0m35.130s
sys 0m3.300s
j@j-desktop:~$ time { for i in {0..999}; do unlzma -c 18x18ko.pcf.lzma > /dev/null ; done }
real 2m48.090s
user 2m35.814s
sys 0m8.945s
j@j-desktop:~$
-----
I don't understand why there is so much difference since the decompression algorithm is quite the same.
ProblemType: Bug
Architecture: amd64
Date: Thu Oct 8 17:13:37 2009
Dependencies:
libgcc1 1:4.2.4-1ubuntu4 [modified: lib/libgcc_s.so.1]
libstdc++6 4.2.4-1ubuntu4 [modified: usr/lib/
gcc-4.2-base 4.2.4-1ubuntu4
libc6 2.7-10ubuntu5 [modified: lib/ld-2.7.so lib/libc-2.7.so lib/libcrypt-2.7.so lib/libdl-2.7.so lib/libm-2.7.so lib/libnsl-2.7.so lib/libpthread-
DistroRelease: Ubuntu 8.04
NonfreeKernelMo
Package: lzma 4.43-12ubuntu1 [modified: usr/bin/lzma usr/bin/lzma_alone]
PackageArchitec
ProcEnviron:
PATH=/
LANG=fr_FR.UTF-8
SHELL=/bin/bash
SourcePackage: lzma
Uname: Linux 2.6.24-24-generic x86_64
I wonder if it is related to that but the Tomshardware.com site found that (un)7zip was slower that (un)zip too:
http:// media.bestofmic ro.com/ 7/Y/247822/ original/ filecompdecompl ucid.png