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Full Discussion: Help optimizing sort of large files
Top Forums UNIX for Advanced & Expert Users Help optimizing sort of large files Post 302925455 by Corona688 on Monday 17th of November 2014 10:10:34 AM
Old 11-17-2014
Quote:
Originally Posted by kogorman3
Defragged? I'm not sure how to do that on Linux, so I am using a fresh 2-TB drive formatted ext4 and directing sort to use it for temporaries. It's otherwise empty.
ext4 partitions are relatively easy to defrag, being designed with runtime defragmentation in mind (yes, runtime -- no need to unmount) via the e4defrag utility. There's no point defragging an empty partition, but check that your input and output partitions aren't a mess after all this testing.
Quote:
I've got 32 GB RAM and a 64-bit CPU. That's big enough for the whole test file, but the parameters to sort don't let it work that way.
The process of merge-sorting doesn't work that way. No matter how big your buffers are, it has to do the same number of merges on the same number of elements of the same sizes, nearly all of them tiny... Starting with billions of 2-element merges, half the number of 4-element merges, etc, etc, etc. (A little oversimplification, but the merging options don't substantially change this.) That's why pushing buffers to ridiculous sizes is so little help -- they're nearly always dead weight except for the final merge, when it's never going to be big enough to matter anyway.
Last edited by Corona688; 11-17-2014 at 11:17 AM..
 

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LEARN ABOUT DEBIAN

avimerge

avimerge(1)						      General Commands Manual						       avimerge(1)

NAME

       avimerge - merge several AVI-files into one

SYNOPSIS

       avimerge -o name -i file1 [ file2 [ ... ] ] [ -p file ] [ -a num ] [ -A num ] [ -b num ] [ -c ] [ -f commentfile ] [ -x indexfile ]

COPYRIGHT

       avimerge is Copyright (C) by Thomas Oestreich.

DESCRIPTION

       avimerge is a  versatile tool.  It can contatenate several AVI files into one. It can also be used to fix an index of a broken file and can
       also replace audio tracks or muxes new ones. It can read raw AC3 and MP3 files for multplexing.

OPTIONS

       -o name
	      Specify the name of the output file.

       -i file
	      Specify the name(s) of the input file(s) to merge into the output file.

       -p file
	      Specify the name of the audio file to multiplex into the output file. The type of file can be either another AVI file or an MP3 or
	      AC3 file.

       -b num Specify if avimerge should write an VBR mp3 header into the AVI file. Default is dependent on the input file (and usually correct).
	      num is either 1 or 0.

       -c     Drop video frames in case audio is missing [off]
	      Only when merging multiple AVI files. Some AVI files run a little bit (usually for one or two video frames) short on audio. This
	      means avimerge cannot keep up sync when concatinating them. The files play fine when played individually but not when merged because
	      audio from the new file gets played back with video from the old file.  avimerge will print a message like

		No audiodata left for track 0->0 (59950.25=59950.25) continuing ..

	      When you turn on the -c option, the video which is too much will be dropped.

       -f commentfile
	      Read AVI tombstone data for header comments from commentfile. See /docs/avi_comments.txt for a sample.

       -x indexfile
	      Read the AVI index from indexfile.  See aviindex(1) for information on how to create such a file.

       -a num Specify the number of the audio track you want to use from the input file.

       -A num Specify the number of the audio track you want to use in the output file. If you specify an existing track number, the track will be
	      replaced. If omitted, the next free slot will be used.

EXAMPLES

       The command

       avimerge -o big.avi -i my_file1.avi my_file2.avi my_file3.avi

       merges the three input files my_file[123].avi into one big AVI-file big.avi.

       avimerge -o out.avi -i in.avi -p audio2.avi -a 1

       merges track number 1 form in.avi to the next free track number in out.avi. You can create audio-only AVI-files using

       transcode -i song.mp3 -x null,mp3 -g 0x0 -y raw -a 1 -o audio2.avi -u 50

       The command

       avimerge -o out.avi -i in.avi -p sound.mp3

       merges the file sound.mp3 as an additional audio track into out.avi.

AUTHORS

       avimerge was written by Thomas Oestreich
       <ostreich@theorie.physik.uni-goettingen.de> with contributions from many others.  See AUTHORS for details.

SEE ALSO

       aviindex(1), avifix(1), avisplit(1), tccat(1), tcdecode(1), tcdemux(1), tcextract(1), tcprobe(1), tcscan(1), transcode(1)

avimerge(1)							 26th January 2004						       avimerge(1)
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