Mercury Interactive's LoadRunner is the main tool that I use for performance testing, and to really get the most out of the tool, there are some things that will help 'tune' your LoadRunner installation so that it will scale better (for testing, of course :-) ). Some of these tips were available in LoadRunner's guide and web site, some I've picked up along the way. Unfortunately, I've mostly only used LoadRunner in Windoze environment, so most of these only applies to that OS only -- sorry.
This seems to be the best set of patches to use for performing Web based performance testing:
To enable the increased number of Vusers, modify the following settings on each host machine:
Web scalability patch will add some Windows registry entries to help tune the TCP stack.
Make the following modification to the Windows Registry:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\SubSystems\Windows
The existing value is probably something like this:
%SystemRoot%\system32\csrss.exe ObjectDirectory=\Windows SharedSection=1024,3072 Windows=On SubSystemType=Windows ServerDll=basesrv,1 ServerDll=winsrv:UserServerDllInitialization,3 ServerDll=winsrv:ConServerDllInitialization,2 ProfileControl=Off MaxRequestThreads=16
The SharedSection=1024,3072 key has the format xxxx,yyyy where:
xxxx defines the maximum size of hte system-wide heap (in kilobytes)
yyyy defines the size of the per desktop heap.
Change the yyyy seting to 8192 (which is 8MB).
Close regedt32.
Change the second numeric value in the 'Windows SharedSection=1024,3072 Windows' to '4096' or other higher