Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!husc6!m2c!applix!jim
From: jim@applix.UUCP (Jim Morton)
Newsgroups: comp.sys.ibm.pc.rt
Subject: Re: Compression format of AIX
Summary: more on pack vs. compress
Message-ID: <1003@applix.UUCP>
Date: 6 Oct 89 14:54:19 GMT
References: <13906@well.UUCP> <1989Oct3.221135.21254@acheron.uucp>
Organization: APPLiX Inc., Westboro MA
Lines: 35

In article <1989Oct3.221135.21254@acheron.uucp>, Ed Clarke writes:
> It's quicker/easier to unpack a file rather than to uncompress it.

My immediate reaction was "no way!" but rather than shoot first, I
tried both for a copy of a 745k unix kernel - a sample binary. Text
files have more dramatic results in favor of compress. The results
below show about twice as long to compress vs. pack, but around the
same time to decompress vs. pack. Considering that in my experience
compress ALWAYS gives smaller output size, I always use compress.

Results:	(RT model 125, AIX 2.2.1, 8meg memory)
# ls -las unix*
1464 -r--r--r--   1 root     system    745892 Oct  6 10:27 unix.1
1464 -r--r--r--   1 root     system    745892 Oct  6 10:28 unix.2
# time pack unix.1
pack: unix.1: 18.3% Compression
real       15.7 user        9.7 sys         1.0
# time compress -v unix.2
unix.2: 745892 chars in, 269927 codes (508253 bytes) out, compression 149.17%
Compression as in compact: 32.11%
Largest code (of last block) was 62532 (16 bits)
real       43.0 user       31.8 sys         0.7
# ls -las unix*
1196 -r--r--r--   1 root     system    609483 Oct  6 10:27 unix.1.z
1000 -r--r--r--   1 root     system    508253 Oct  6 10:28 unix.2.Z
# time unpack unix.1
unpack: unix.1: unpacked
real       36.1 user       23.3 sys         2.5
# time compress -dv unix.2
unix.2.Z:  -- replaced with unix.2
real       41.5 user       17.3 sys         1.8

--
Jim Morton, APPLiX Inc., Westboro, MA
...uunet!applix!jim    jim@applix.com