Operating System - OpenVMS
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Floating Point Calculations

John A. Quinn
Occasional Contributor

Floating Point Calculations

Is there any way to either monitor or get a snapshot of the Floating Point Accelerator utilization? Background: My client is migrating from VMS to Solaris and is thinking about purchasing one of Sun's units with multiple processors but only one Floating point accelerator. In order to determine if it will work, we need to find out how much the FPA is being using on the VMS (7.3-1) system where the application (Oracle) is currently running.


Hein van den Heuvel
Honored Contributor

Re: Floating Point Calculations

It is very hard to conceive an Oracle based application which would be Floating point intensive. Even if all the column in the singnificant table were floating point variables, then still I would expect more that 5% of the cpu time to be floating point operations. Oracle applications spend a good chunk of their time figuring out what to do and how to do it, they gather up teh database pages to look at, move some data around, touch actual columns, then move it all back over TNS or an API. It's all following pointers, doing hashes, moving memory.
So I could never recommend a floating point accelerator for that. but why not ask the SUN polfs for pertinent data points under which circumstances an Oracle application coudl be helped by one?
Form the VMS side I woudl focus my activity on 'PCA' or DCPI or SDA for program coverage analysis. Is the application CPU time spend within user code? Then floating point could be intenses? In VMS or it's RTL's? --> zero FP, In Oracle? which modules? Parser? Comms? Buffer cache? IO?