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Date:      Fri, 1 Jun 2001 13:42:01 -0700 (PDT)
From:      John Polstra <jdp@polstra.com>
To:        ports@freebsd.org
Subject:   Re: Supporting pkg-plist.gz ?
Message-ID:  <200106012042.f51Kg1U29811@vashon.polstra.com>
In-Reply-To: <Pine.BSF.4.21.0106011314060.51937-100000@sobek.openirc.co.uk>
References:  <Pine.BSF.4.21.0106011314060.51937-100000@sobek.openirc.co.uk>

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In article <Pine.BSF.4.21.0106011314060.51937-100000@sobek.openirc.co.uk>,
George Reid  <greid@FreeBSD.ORG> wrote:
> On Fri, 1 Jun 2001, Ernst de Haan wrote:
> 
> > Decompressing all pkg-plist files on forehand doesn't sound like a good idea,
> > since the other approach supports a multi-threaded/processing approach. The
> > performance will in my expectation be much higher, since downloading is
> > typically much slower than (de)compressing for the size of files we are
> > talking about (between 1K and 1M).
> 
> If CVSup were to support locally compressed files, each local file would
> have to be decompressed first, the delta applied and then recompressed
> (since you can't decompress "a bit" of the local file). This is obviously
> more efficient than decompressing all of the plist files, cvsupping as
> normal and then recompressing.
> 
> It is however, perhaps too drastic a change, since it definitely wouldn't
> work in the case where the entire repository was mirrored (i.e. it would
> break the standard CVS tools). I know nothing of the cvsup internals or
> Modula-3, so this is probably best left to the authors.

That would be me. :-) I don't think it's worth pursuing, at least not
for pkg-plist files.  I looked at my ports tree, which is just a few
days old.  It contains 4894 pkg-plist files.  Of those, 3479 (71%)
can't be compressed at all.  The reason is that their sizes are 1024
bytes or less.  That is the default fragment size (smallest unit of
allocation) in UFS filesystems, which means that any file from 1-1024
bytes in size will use the same amount of space on the disk.  You
could compress each of those files by a factor of 10 without freeing
up a single block on your disk.

The sum total of all the pkg-plist files is only 22 MB, which isn't
worth walking around the corner to save.  Megabytes ain't what they
used to be, you know. :-)

John
-- 
  John Polstra                                               jdp@polstra.com
  John D. Polstra & Co., Inc.                        Seattle, Washington USA
  "Disappointment is a good sign of basic intelligence."  -- Chögyam Trungpa


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