Monthly Archives: November 2008

GCC Hacks…

IBM DeveloperWorks has a pretty decent article on some GCC hacks used or referenced in the Linux kernel. I especially like the bit about Branch Prediction Hints. Check it out at http://www.ibm.com/developerworks/linux/library/l-gcc-hacks/

Posted in Linux, Tuning | Tagged , | 1 Comment

Using R to look at your vmstat data…

So – you’ve collected some vmstat data (with timestamps, of course) and you want to show the information in R. Well here’s how I did it. In this case, the purpose was to prove the weak correlation between the CPU … Continue reading →

Posted in AIX, Linux, Oracle, Perl, Scripts, Solaris, Tuning, UNIX, WebSphere | Tagged , , , | Comments Off

VMSTAT with date/time stamps!!!

So – I’ve been asked several times recently about collecting vmstat data. The biggest issue most folks face, is that vmstat on most UNIX platforms does not give you a date/time stamp of any value (if any). Here it is, … Continue reading →

Posted in AIX, Linux, Perl, Scripts, Solaris, Tuning, UNIX | Tagged , , , , , | 1 Comment

AIX numperm%

numperm% is the percentage of RAM used for FS Cache. You can check its current value with vmstat -v. There doesn’t appear to be any real benefit to forcing the minperm and maxperm to be lower unless you see the … Continue reading →

Posted in AIX, DB2, Oracle, Tuning, WebSphere | Tagged , , , , , | 2 Comments

Faster ways to copy large files on UNIX

On several occasions, we’ve needed to copy large files as part of operating system maintenance, migrations, etc… While your first instinct might be to use the cp command for large files, the dd command might save a lot of time. … Continue reading →

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