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Re: performance and +DAportable

 
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Ian Lochray
Respected Contributor

performance and +DAportable

I have a large application that is written in C and COBOL. I want to build it on a PA RISC 2.0 chip but I want my customers who still have PA 1 chips to be able to run it so I compile with the +DAportable option. I want to know if there are any performance implications of this when compared with buildingthe application on a PA 1 chip.
5 REPLIES 5
Rainer von Bongartz
Honored Contributor

Re: performance and +DAportable


I have done this kind of thing and didn't notice nor measure any performance implications.

He's a real UNIX Man, sitting in his UNIX LAN making all his UNIX plans for nobody ...
Herve BRANGIER
Respected Contributor

Re: performance and +DAportable

Hi

Reading information it seems that performances
are falling... but we do that without measurables
differences....

Regards

Herv?

A. Clay Stephenson
Acclaimed Contributor
Solution

Re: performance and +DAportable

Hi Ian,

I doubt that you will see any degradation in any COBOL application since these tend to be I/O intensive rather that computationally intensive. The only cases in which I have observed any measurable differences in performance involved analysis programs in C involving very large arrays and very complex math. In that case, the performance hit was about 4% (in that particular section of code) but in the vast majority of cases, you will find that the hit is not measurable.

In any event, the proper course is to compile and link using both options and measure but I think all will be well if you choose portable.

Regards, Clay
If it ain't broke, I can fix that.
Mike Stroyan
Honored Contributor

Re: performance and +DAportable

One thing you can do to compromise is to use +DAportable and +DS2.0 to make the compiler use PA1.1 features but schedule instructions to run best on PA2.0 systems. The default scheduling for +DAportable can be very far from optimal for modern systems.
Andrew Cunningham
Frequent Advisor

Re: performance and +DAportable

On our computationally intensive C/C++ application I found at least a 20-30% performance hit on our B1000 when running +DAportable compiled ( latest aCC, HP-UX 10.2).