Processor performance issue

[Yaboto]

What are the commands in HP-UX OS I need to use to check the load on processor and memory ressources, and to advice wether I need to purchase additional processor or  memory ?

Thanks !

[Bill Hassell]

For processor usage, use the command: top  (ctrl-C to exit)

The processes using the most CPU are listed at the top.

For memory, use: swapinfo -tam

To sort the processes by memory usage: UNIX95=1 ps -e -o vsz,pid,ppid,args | sort -rn | head -20

To see if memory usage is very high and more memory is needed, look at the swapinfo values. The memory line will show current usage while the total line shows all memory usage including swap. Swap space is mapped and used when there isn't enough memory available. From a performance point of view, swapping (paging) is very bad and can only be fixed with more RAM.

If you have Glance installed (optional priced product), the metrics are much easier to see.

[Matti_Kurkela]

Assuming that no additional software (like Glance) is installed, the "vmstat" command might be the best.

If the average of the values in the Page-Out column (po) is significantly different from 0, more memory is needed.

Small non-zero po values or very rare short-term high po spikes might be tolerable, but if the average po value over long term (minutes/hours) is high, the system needs to frequently move things in and out of swap, which will ruin your performance.

For processor resources, look at the CPU idle percentage (the id column). If it is near 0% frequently, your system is working about as hard as it can with the current CPUs. At that point, you'll need to understand the nature of the system's workload: does it require interactive response or is it batch processing?

For interactive response systems, check the users' opinion: if the users say the system becomes "unusably slow" at times of peak use, then you'll definitely need more processing power; but if the users find the system "OK but not great" then the current processors might be handling the current workload just fine. In that case, you will have to pay attention to any changes that might increase the workload of the system and be prepared to re-evaluate as necessary, or to proactively get more processing power to get some capacity reserve.

For batch processing, running the system so hard it has 0% idle over long periods of time may not be harmful at all. Instead, you should pay attention to the amount of work completed: for example, if a system with heavy night-time batch jobs runs at 0% idle for several hours at a time at night but always completes all the jobs several hours before the results are needed (e.g. at the start of the next business day), it might be OK. In this kind of use, 0% idle means that you're efficiently using all the processing power you have.

[Dennis Handly]

Your system can also be slow if you are doing lots of disk I/O.

Here is may or may not be helpful to add additional RAM for the filecache.