Hi,

which OS do you run - I assume it's AIX? And why do you want to do it at all - are you running so low in resources that a simple command execution / a running process will put your system into trouble? Or do you expect your application to be so badly written that it will negatively impact the system for a certain amount of time?

If it's AIX, vmstat or sar or any kind of command collecting once off data will not impact your performance at all, while interactive monitoring tools like topas or nmon will. On unix you should not average anything since the resource usage is 'at a given moment in time' and will change about 1000 times per second anyway - so most of these tools are internal averaging the interval between executions.

Saying this, where would you set your threshold anyway. AIX using vmm and constantly re-nicing its processes, is absolutely capable to run in (and depending hardware/setup/virtualization overrun) its cpu entitlement without any kind of problems - and if you're overutilizing your memory for a short time, and your system is properly tuned, this will not slow down your system either (an AIX box with proper sizing and 'enough' memory uses normally 70-80% memory computational and gives you the headroom of 20% memory for peak times).

Not knowing your system / application at all, I would say 'it depends on how long you expects your threads to run and what they're doing overall' - on a DB box I would monitor the system in 1 - 2 second intervals for using all resources more than 3 intervals - but as stated - when I use virtualization and have a large shared pool where I can get 1000% cpu in case I need it, I just don't have to monitor it at all. And if you have p6 systems and large shared memory pools, too - I would not even do it for memory.

zxmaus