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Special Forums Hardware Filesystems, Disks and Memory Performance Hit With Many Files Post 302294978 by MarkSeger on Friday 6th of March 2009 08:59:24 AM
Old 03-06-2009
I too have done similar testing but slightly different. Rather than simply time the creation of 100 files, which can be very misleading OR timing the creation of 1M files which is no better, I prefer to look at what is happening across the system resources during the entire event.

I run collectl with a monitoring interval of 1 second, logging to a file or simply watching the system in real time. When I create a million files I can watch the cpu periodically increase. In fact, when getting in the higher ends of files I can actually see spike in cpu load. This is something you can't see when just doing end-to-end numbers.

Another interesting test is to set up an alarm in your script to write out the number of files created every 10th (or even hundredth) of a second. You'll be amazed to see how linearly the number of files created/second drops over time as well as how things periodically slow down but are not visible when only looking at second-level samples.

You can also run collectl at a monitoring interval of 0.1 seconds and see micro-spikes in CPU load as well. This is something most people miss because none of the existing tools can deal with sub-second reporting.

-mark
 

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GENPLOTFILES(1) 						      colplot							   GENPLOTFILES(1)

NAME
genplotfiles - utility to help automate creation of collectl plot file from raw ones SYNOPSIS
/opt/hp/colplot/genplotfiles.pl -outdir [-switches] DESCRIPTIONS
This utility is not intended to meet all plot file creation needs, but quite frankly should meet most. Features not provided with this utility are best realized by running collectl directly in playback mode (see collectl -p). It is therefore important to understand what this utility will and will not do for you before building an automation strategy around it. The algorithm used is fairly simple - genplotfiles examines each collectl raw file to see it it falls within the data ranges (if specified) and contains a matching hostname (if specified). If a plot file already exists, the timestamps are compared and the raw file skipped if its newer than the plotfile. Any raw files that pass all these tests are then passed to collectl with their timestamp wildcarded. The result is all raw files for that host/date will be processed. This means if you copy over collectl raw files multiple times over the course of the day using rsync, you can immediately genererate up-to-date plots for them using genplotfiles. Furthermore, you won`t even need any date parameters if the older plot files are alreay up to date. For an example of what a cron job that aggregates multiple collectl logs onto a single system for plotting purposes, see crontab.sh in the same directory as this script. SWITCHES
All switches are optional with the exception of -outdir: -colbin path-to-collectl This points to collectl and is only necessary if /usr/sbin is not in your path or you`ve chosen to install collectl in a non-stan- dard directory. -debug number Primarily for development, will provide intermediate processing information based on its value. See souce for details. -force Always generate plot files even in there is an existing one that is newer than the latest raw file. This will be necessary if you want to rerun this script and just change the value of -subsys. -help Print a summary of available switches. -host string Only process files that contain this string in their hostname portion of the filename. -indir directory Directory where to look for collectl logs. The default is /var/log/collectl and is therefore only necessary if your logs are in a non-standard location. -outdir directory Directory into which to write the plottable files. This field is required. -fromdate date Ignore files with a datestamp in their name less that this value. The default is 20050101 and so defaults to all files. The value of `yesterday` is also recognized to simplify scripts that call this. -thrudate date Ignore files with a datestamp in their name with a datestamp greater than this value. The default is the current day and one can also specify a value of `yesterday`. -subsys string Instead of using the default subsystems for which data was collected, generate output files based on this set. There are basically two reasons for doing this. The first is that you may want to reduce the size of the plot files, though with compression there is rarely much point in this. The second is if you`ve asked collectl to collect summary data but want to plot detail data. See the colplot FAQ for more information. AUTHOR
This program was written by Mark Seger (mjseger@gmail.com). Copyright 2005 Hewlett-Packard Development Company, L.P. SEE ALSO
LOCAL
OCTOBER 2005 GENPLOTFILES(1)
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