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Top Forums Shell Programming and Scripting Increase the performance of find command. Post 303041939 by jim mcnamara on Saturday 7th of December 2019 09:28:02 AM
Old 12-07-2019
This standard library call: nftw (or ftw)
IBM Knowledge Center

supports the find command traversing directory file trees - i.e., searching and locating files.

Assuming you want to keep the command you already have (and I am not sue that Rudi's suggested test is valid because of file and directory caching ):

A limiting factor is known to be the number of sub-directories in the file tree, and possibly the number of available open file descriptors - a per process limit.
If you can parallelize your code using several processes it may improve performance. I'm not sure this will help much because it depends on the number of sub-directories being large to gain any benefit. The developers who write system code try to maximize throughput.

What I'm saying is: performance enhancement work is subjective and often a misplaced resource and a waste of programmer time.
Suppose your command runs in one minute in production. Then you work hard and get it down to 35 seconds. The user perception of "slow" will still be there, so you have to get it down to maybe 6 seconds to make users happy and see it as "faster". In this case getting an order of magnitude improvement may not be possible.

And in this case you would have to do something about directory caching messing up testing because (you check this yourself) once you open a directory the system caches it for speedier access. Use the time command and rerun the command to see what I mean:
Code:
time [my long command goes here]
#write down the result
time [my long command goes here]
# write down the result and compare the two resulting times

This User Gave Thanks to jim mcnamara For This Post:
 

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AFS-UP(1)						       AFS Command Reference							 AFS-UP(1)

NAME
up - Recursively copy directories, preserving AFS metadata SYNOPSIS
up [-v] [-1] [-f] [-r] [-x] [-m] <source directory> <destination directory> DESCRIPTION
The up command recursively copies the files and subdirectories in a specified source directory to a specified destination directory. The command interpreter changes the destination directory and the files and subdirectories in it in the following ways: o It copies the source directory's access control list (ACL) to the destination directory and its subdirectories, overwriting any existing ACLs. o If the issuer is logged on as the local superuser root and has AFS tokens as a member of the group system:administrators, then the source directory's owner (as reported by the "ls -ld" command) becomes the owner of the destination directory and all files and subdirectories in it. Otherwise, the issuer's user name is recorded as the owner. o If a file or directory exists in both the source and destination directories, the source version overwrites the destination version. The overwrite operation fails if the first (user) "w" (write) mode bit is turned off on the version in the destination directory, unless the -f flag is provided. o The modification timestamp on a file (as displayed by the "ls -l" command) in the source directory overwrites the timestamp on a file of the same name in the destination directory, but the timestamp on an existing subdirectory in the destination directory remains unchanged. If the command creates a new subdirectory in the destination directory, the new subdirectory's timestamp is set to the time of the copy operation, rather than to the timestamp that the subdirectory has in the source directory. The up command is idempotent, meaning that if its execution is interrupted by a network, server machine, or process outage, then a subsequent reissue of the same command continues from the interruption point, rather than starting over at the beginning. This saves time and reduces network traffic in comparison to the UNIX commands that provide similar functionality. The up command returns a status code of 0 (zero) only if it succeeds. Otherwise, it returns a status code of 1 (one). This command does not use the syntax conventions of the AFS command suites. Provide the command name and all option names in full. OPTIONS
-v Prints a detailed trace to the standard output stream as the command runs. -1 Copies only the files in the top level source directory to the destination directory, rather than copying recursively through subdirectories. The source directory's ACL still overwrites the destination directory's. (This is the number one, not the letter "l".) -f Overwrites existing directories, subdirectories, and files even if the first (user) "w" (write) mode bit is turned off on the version in the destination directory. -m Recognize and copy mount points rather than traversing the volumes they reference during the recursive copy operation. Without -m, up's default behavior is to copy the contents of all volumes and subvolumes mounted under the source directory into the volume containing the destination directory. -r Creates a backup copy of all files overwritten in the destination directory and its subdirectories, by adding a ".old" extension to each filename. -x Sets the modification timestamp on each file to the time of the copying operation. source directory Names the directory to copy recursively. destination directory Names the directory to which to copy. It does not have to exist already. EXAMPLES
The following command copies the contents of the directory dir1 to directory dir2: % up dir1 dir2 PRIVILEGE REQUIRED
The issuer must have the "a" (administer) permission on the ACL of both the source and destination directories. COPYRIGHT
IBM Corporation 2000. <http://www.ibm.com/> All Rights Reserved. This documentation is covered by the IBM Public License Version 1.0. It was converted from HTML to POD by software written by Chas Williams and Russ Allbery, based on work by Alf Wachsmann and Elizabeth Cassell. OpenAFS 2012-03-26 AFS-UP(1)
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