Package: squashfs-tools
Version: 1:4.2-5
Severity: normal
Befause of the compressor settings used in this package, to decompress
either the source package or the deb packages created by this package
requires
65 Megabytes of memory, which is alot, when it is taken into account
that this
is for absolutely no benifit.
The reason/problem here is warned on in the xz(1) man page---raising the
compression
options of xz increases the dictionary sie the compressor uses. Using a
dictionary larger
than the uncompressed file is completely useless, and the entire
dictionary must be
in memory during decompression.
What you want for highest compression levels, while using lower
dictionary sizes, is xz's
"extreme" option, however I don't think dpkg-deb exposes this.
In the meantime, the default option -6, is very good, with a 8MB
dictionary, however
in my experimentation, using -4 or -2 keeps almost the same compression
(and on small package
-2e and -4e, e for --extreme) would get exactly the same compresion.
Anyways, as this package is very useful on embedded systems, I think it
is unacceptable to
have this package using a compressor dictionary size on the .deb
packages
any larger than the default of 8MB.
>From the xz man page:
" The differences between the presets are more
significant than
with gzip(1) and bzip2(1). The selected compression
settings
determine the memory requirements of the decompressor,
thus using
a too high preset level might make it painful to
decompress the
file on an old system with little RAM. Specifically, it's
not a
good idea to blindly use -9 for everything like it often
is with
gzip(1) and bzip2(1).
"
-- System Information:
Debian Release: wheezy/sid
APT prefers testing
APT policy: (500, 'testing'), (1, 'experimental')
Architecture: armel (armv5tel)
Kernel: Linux 3.4.0-tomoyo-00006-gfd64aac (PREEMPT)
Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)
Shell: /bin/sh linked to /bin/dash
Versions of packages squashfs-tools depends on:
ii libc6 2.13-33
ii libgcc1 1:4.7.1-2
ii liblzma5 5.1.1alpha+20120614-1
ii liblzo2-2 2.06-1
ii zlib1g 1:1.2.7.dfsg-13
squashfs-tools recommends no packages.
squashfs-tools suggests no packages.
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