Archive
Posts from 2008
Viewing Solaris zone resource utilization
Solaris zones have been around for quite some time now, and provide low overhead execution environments for running application. Admins who need to understand how zones are utilizing CPU and memory resources typically turn to prstat, which provides the "-Z" option to view utilization by zone: While reviewing the Solaris zones mailing list last night, I noticed that Jeff Victor posted a link to a Perl script that can provide utilization data for zones. This script has a TON of potential, especially once it is able to report on network and disk utilization.
$ read more →Deciphering shell exit codes
I was recently debugging an issue with a shell script, and noticed that the shell was exiting with an exit code greater than 100 when it received a SIGTSTP signal: I was curious where the exit value of 146 came from, so I did a bit of digging. It turns out that when a shell exits due to an uncaught signal, the signal number is added to 128 and that is the value that is returned. So in the case above, the exit code 146 was returned. I digs me some random shell knowledge.
$ read more →Debugging Java performance problems presentation
I recently gave a presentation at the local UNIX users group titledDebugging Java performance problems. The presentation describes various opensource tools and how they can be used to understand what is causing CPU, memory and lock contention issues inside a Java virtual machine. If there are additional tools not discussed in the presentation that you find useful for debugging Java performance problems, please let me know through the comment feature.
$ read more →Linux's work to scale vertically?
Slashdot and other sites had mention of the release of the 2.6.27 Linux kernel today. Some of the new features in the kernel come from the KernelNewbies Linux 2.6.27 notes about improved SMP support for the page cache: The page cache is the place where the kernel keeps in RAM a copy of a file to improve performance by avoiding disk I/O when the data that needs to be read is already on RAM. Each "mapping", which is the data structure that keeps track of the correspondence between a file and the page cache, is SMP-safe thanks to its own lock. So when different processes in different CPUs access different files, there's no lock contention, but if they access the same file (shared libraries or shared data files for example), they can hit some contention on that lock…
$ read more →Concert review Cowboy Mouth
I have been a long time Cowboy Mouth fan, and still remember the first time I saw them play a concert in Delaware. They had an incredible amount of energy, and where one of the few bands I had seen that wanted the crowd involved in every aspect of the show. When I heard they were playing one of the local festivals here in town, I decided to venture out with a few friends to see them. The show started off like all Cowboy Mouth shows with a ton of energy, and the lead singer (who also plays drums) jamming on drums to get the crowd into the show…
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