Can you boost your Oracle database performance on HP-UX for free?


Database performance, as is true with all performance related matters, has to do with resources.

This story specifically focuses on a real life experience with Oracle database performance on HP Unix running on Intel integrity CPU’s like these:

CPUinfo

The issue with installation is the hyper-threading aka. the use of the logical processors.
When the server is booted and is running, you can do basic performance review with a default tool like top.

lcpu_attr=0

In this exact case the server is running fine and there is no need to investigate further. But, in cases where there were performance issues, it would be a good idea to be aware of the numbering of the CPU’s in this overview (0, 2). This numbering suggests there would also be a ‘1’ and, where there would be a ‘1’ there would probably also be a ‘2’…

Yes there is and it is called ‘lcpu_attr’. A HP Unix kernel parameter which is, to my taste, a bit odd, not well known or well documented…

lcpu_attr (Tunable Kernel Parameter)

When turned on, lcpu_attr activates the logical CPU’s immediately. When you run top again, this is what it’ll look like (immediately)

lcpu_attr=1

Okay! Great… but… there are some catches.
This parameter lcpu_attr is a dynamically tunable kernel parameter but… it’ll crash your databases. So you will need a minimum of planned downtime for this action.

Also, you can set hyper-threading on in the EFI boot-loader.
But then you should be aware of this!

In the end, in this real-life story, we helped the situation advance by just doing:

1. stopping Oracle database(s)
2. kctune lcpu_attr=1
3. starting Oracle databas(s)

All in all, it could be not difficult to boost your Oracle database performance on HP-UX for free!

Thanks to my good friend Gerard van der Kooij for finding the final link!


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