Performance Hit With Many Files Post: 302294978

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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

03-06-2009

Registered User

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

MarkSeger

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LEARN ABOUT DEBIAN

jfs_logdump

jfs_logdump(8)						  JFS utility - journal log dump					    jfs_logdump(8)

NAME

       jfs_logdump - dump a JFS formatted device's journal log

SYNOPSIS

       jfs_logdump [ -a ] device

DESCRIPTION

       jfs_logdump dumps the contents of the journal log from the specified JFS formatted device into output file ./jfslog.dmp.

       device is the special file name corresponding to the actual device from which the journal log will be dumped (e.g.  /dev/hdb1 ).

       jfs_logdump must be run as root.

OPTIONS

       -a     Dump the entire contents of the journal log instead of just the committed transactions since the last synch point.

EXAMPLE

       Dump the entire JFS journal log from the 3rd partition of the 2nd hard disk into ./jfslog.dmp:

	      jfs_logdump -a /dev/hdb3

REPORTING BUGS

       If you find a bug in JFS or jfs_logdump, please report it via the bug tracking system ("Report Bugs" section) of the JFS project web site:
       http://jfs.sourceforge.net/

       Please send as much pertinent information as possible, including any jfs_logdump error messages and the complete output of running jfs_fsck
       with the -v option on the JFS device.

SEE ALSO

       jfs_fsck(8), jfs_mkfs(8), jfs_fscklog(8), jfs_tune(8), jfs_debugfs(8)

AUTHORS

       Barry Arndt  (barndt@us.ibm.com)
       William Braswell, Jr.

       jfs_logdump is maintained by IBM.
       See the JFS project web site for more details:
       http://jfs.sourceforge.net/

								 October 29, 2002						    jfs_logdump(8)